JP2002312938A - Optical disk recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of a reading error by automatically correcting the fluctuation of the pit length or the land length due to the kind of disk. SOLUTION: A recording signal modulating means 16 modulates, a recording signal Sw with a prescribed Write Strategy and records the modulated signal on the optical disk 10. A reproduced signal Sr outputted from the optical head 14 is measured by a pit length measuring circuit 26. By a means 36 for correcting the regulation of modulation, the Write Strategy used in the recording signal modulating means 16 is corrected so as to reduce the error of the pit length with respect to the normal length in accordance with the measurement result of the pit length.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mark length recording type optical disk recording apparatus for recording information on an optical disk by a combination of a pit length and a land length, and relates to pits and lands (refer to a portion between pits). This automatically corrects the variation of the length due to the type of the disc, the difference between the inside and outside of the disc, and the like, always realizes a good recording state, and prevents the occurrence of a reading error.

[0002]

2. Description of the Related Art As one standard of an optical disk recording system, a CD-WO which performs write-once recording in a CD format.
(CD Write Once) standard. In the CD-WO standard, the recording pit length is 3 to 11T (1T = 1 / 4.32).
(18 MHz = 231 ns) is used, but when a laser beam having a pulse width corresponding to the pit length to be formed is irradiated, pits are actually formed about 1T longer due to residual heat. Therefore, for example, as shown in FIG. 2, a pulse width (n-1) T + α shorter than the pit length to be formed by about 1T.
(NT), that is, 2T + 30 when forming a 3T pit
~ 70ns pulse width, 3T + 20 ~ when recording 4T
40ns pulse width, 4T to record 5T to 11T
The recording laser light is irradiated with a pulse width of 10T. Since the pit length also varies depending on the land length immediately before the pit, the irradiation time and the irradiation start timing are changed according to the land length immediately before the pit. Further, if recording is performed with a constant recording power, the leading edge of the pit is not formed correctly. Therefore, as shown in FIG. 3, the laser power is increased at the leading edge of the pit for a predetermined period. The rule for modulating the recording signal irradiation time, irradiation start timing, recording power, and the like according to the pit length and land length to be formed is called a write strategy.

[0003]

The optimum setting contents of Write Strategy differ depending on the type of disc (difference between manufacturers, etc.). In addition, even when the recording state of the recording film is different between the inner circumference side and the outer circumference side even in the same disk, the optimum setting contents of the write strategy change every moment.

However, the conventional optical disk recording device has
The Write Strategy was fixed, and items such as pit length and jitter were compromised so as to be in the middle of the disc showing the extreme characteristics. As a result, the formed pit length and land length deviate from the optimum values (logical values), the pit jitter and land jitter increase, and many C1 errors, uncorrectable errors, synchronization errors, and the like have occurred.

The present invention solves the above-mentioned problems in the prior art, and automatically corrects the fluctuation of the pit length and land length due to the type of the disc, the difference between the inside and the outside of the disc, etc. And to provide an optical disk recording apparatus which prevents a reading error from occurring.

[0006]

According to the first aspect of the present invention,
An optical disk recording apparatus of a mark length recording system for recording information on an optical disk by a combination of a pit length and a land length, wherein a recording signal is recorded according to a predetermined rule according to a pit length or a land length to be formed or a pit length and a land length. Recording signal modulating means for modulating the time axis or the time axis and the recording power; and prior to the main recording, the recording apparatus is driven in accordance with a test signal modulated by the recording signal modulating means, and the test signal is transmitted to a test area of the optical disk. Recorded in
And a recording / reproducing head for reproducing the recorded test signal, and a main recording of the optical disc in the recording signal modulating means such that the jitter is reduced according to the test signal reproduced by the recording / reproducing head. And a modulation rule correcting means for correcting the modulation rule of the time axis used at times.

A second aspect of the present invention is an optical disk recording apparatus of a mark length recording system for recording information on an optical disk by a combination of a pit length and a land length. According to the length, the recording signal modulation means for modulating the time axis of the recording signal or the time axis and the recording power according to a predetermined rule,
At the time of the main recording, a recording and reproducing head which is driven in accordance with the recording signal modulated by the recording signal modulating means, records the recording signal on the optical disc, and reproduces the return light from the optical disc at the time of recording, According to the recording signal represented by the return light reproduced by the recording and reproducing head, the modulation rule of the time axis used by the recording signal modulating means is reduced in real time during the main recording so that the jitter is reduced. And a modulation rule correcting means for correcting.

According to the first aspect of the present invention, prior to the actual recording, a test signal is previously recorded in a test area of the optical disk, and the test signal is reproduced to reproduce a pit length error or a land length error or a pit length error. Write Strategy is corrected so as to reduce the error between the length and land length, so pit length and land length errors and jitter can be reduced regardless of the disc type, maximizing the characteristics of the disc, The occurrence of a reading error can be prevented.

According to the second aspect of the present invention, the write strategy is corrected so as to reduce the error of the pit length, the error of the land length, or the error of the pit length and the land length by using the return light during the actual recording. So, Write St in real time
Rategy can be corrected. Therefore, even when the film formation state of the recording film is different between the inner circumference side and the outer circumference side of the same disk, it is possible to set the optimum Write Strategy at each recording position, thereby maximizing the characteristics of the disk,
The occurrence of a reading error can be prevented.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described.
Here, a CD having a recording layer made of various dye-based materials is described.
A case where recording is performed on a WO optical disk will be described. Also, here, the pit length is detected and Write Strategy
Will be described. Since the influence of the pit length also appears on the land jitter, by controlling the pit length to be formed correctly, both the pit jitter and the blank jitter are corrected in a desirable direction (a direction in which the jitter is reduced).

In FIG. 1, an optical disk 10 (CD-W
O optical disk) is set on the turntable 11,
Recording and reproduction of information are performed by a laser beam emitted from the optical head 14 while being rotationally driven by the disk motor 12. The input recording signal S1 is a bit string signal having a pulse width of "1" or "0" corresponding to the pit length and land length to be formed. This recording signal S1
Is input to the recording signal modulating means 16. The recording signal modulation means 16 includes a time axis modulation means 18 and a laser power modulation means 20. The time axis modulating means 18 corrects the time axis such as the rising timing, the falling timing, and the pulse width of "1" and "0" according to the pit length of the recording signal S1 and the land length immediately before it. The laser power modulating means 20 sets the pit formation level of the recording signal Sw to "1".
Is output for a predetermined period from its rise.

The recording signal Sw 'output from the recording signal modulating means 16 is an ALPC (Automatic Laser Power Control).
rol) The laser diode in the optical head 14 is driven through the circuit 22 to emit the recording laser light. The recording laser light is applied to the recording layer of the optical disc 10 to form pits in the recording layer and perform recording. The detection output (reproduction signal) of the return light from the optical disk 10 output from the optical head 14 is transmitted to the pit length measurement circuit 26 via the RF amplifier 24.
Is input to The pit length measuring circuit 26 outputs the reproduced signal Sr
The length of the pit-equivalent portion in is detected.

As a method of detecting the pit length, for example, FIG.
As shown in (1), a method of counting the number of clocks included in a pit-equivalent portion of the reproduction signal Sr using a high-frequency clock can be considered. According to this method, 3T to 11
The length of the pit-equivalent portion of T can be measured with high accuracy (methods for trial recording and real-time
Applicable to any method of compensating Write Strategy).

As another method, as a method applied when test recording is performed, pits of 3T to 11T are repeatedly recorded, and the reproduced signal Sr is converted to a triangular wave generating circuit 28 as shown in FIG. , A triangular wave is generated for each period of “1”, the final value of each triangular wave is obtained, and this is converted into a digital signal by the A / D converter 30. The average value is taken for each 11T pit, and the average value output is output to each pit 3T-1.
There is a method of outputting as a detected value of the pit length of 1T. FIGS. 5B and 5C show examples of the distribution of the pit length for each of the pits 3T to 11T and the average value output for each of the pits 3T to 11T by this method. If the distribution of the pit length is shifted depending on the disk as shown by the dotted line in FIG. 5B, the average value output fluctuates as indicated by X in FIG. 5C. The “length” in FIG. 5B is a value at the time of standard speed reproduction. In the case of high-speed reproduction at n times speed, the length is 1 / n (for example, when n = 4 (4 times speed), 694/4 =
175 ns. ).

[0015] In addition, the Write Strat
As a method applied to the method of correcting tegy, as shown by a dotted line in FIG. 1, the modulated recording signal Sw ′ output from the recording signal modulation unit 16 and the reproduction signal Sr output from the RF amplifier 24 are The waveform is input to the waveform shaping circuit 34 to shape the waveform (the height of the maximum amplitude portion of the reproduced signal Sr is
When the amplitude is adjusted so as to be the same as the amplitude of w ′, and the difference between the recording signal Sw ′ and the reproduction signal Sr is obtained, a signal corresponding to the recorded pit is obtained. A shaped output Sr 'is obtained. ), The microcomputer 36 can measure and output the length (pit length) of the waveform shaping output Sr '. FIG. 6 shows an operation waveform diagram according to this method. According to this method, even when the pit formation state fluctuates between the inner circumference and the outer circumference of the disk, it is possible to correct in real time and always obtain an optimum recording state.

In FIG. 1, the pit length detection output from the pit length measuring circuit 26
(Microcomputer). The modulation rule correction means 36 detects an error of the input pit length detection output with respect to the normal pit length, and corrects the Write Strategy used in the recording signal modulation means 16 so as to correct the error. As a result, the error of the pit length to be recorded is reduced, the jitter is reduced, and the occurrence of a reading error is prevented.

Here, the procedure for correcting the Write Strategy by using a test signal in the optical disk recording apparatus of FIG. 1 and the procedure for correcting the Write Strategy in real time in real recording will be described. FIG. 7 shows a procedure when a test signal is used. First, the optical head 14 is moved to a test area set on the inner peripheral side of the inner peripheral side of the optical disk 10 (S1), and a test signal is generated there (S2) to perform test recording. (S3). After recording, it is reproduced (S4) to detect a pit length or a pit length error (S5), and according to the detected value, a Write Strate is set so as to minimize the pit length error.
gy is automatically corrected (S6), and actual recording is performed (S7).
In the test recording, the test signal is repeatedly recorded while sequentially changing the write strategy, and the test signal is reproduced, and the write signal strategy having the smallest error in the pit length or land length is selected to correct the recording signal modulating means 16. Can also.

FIG. 8 shows a Write Std in real time in this recording.
This is the procedure for setting rategy. During actual recording (S11), return light from the optical disk 10 is detected (S12), and an error with respect to the length of a portion corresponding to the pit of the return light or the normal pit length is detected (S1).
3) According to the detected value, the Write Strategy is automatically corrected in real time so as to minimize the pit length error (S14).

Next, a description will be given of a difference in pit length and a difference in jitter between a case where recording is performed with the Write Strategy fixed as in the prior art and a case where recording is performed by correcting according to the present invention. FIG. 9 shows a measurement result of the pit length error when the Write Strategy is set in accordance with the conventional method for the type A disk. A large error occurs in the pit length for the type B and C disks.
FIG. 10 shows the measurement results of the pit length error when the Write Strategy is corrected according to the type of the disk according to the present invention. The pit length error is almost zero for any of the type A, B and C disks. ing.

FIG. 11 shows the measurement results of jitter when recording is performed by the conventional method.
This shows that the type B land jitter and the type C pit jitter are poor (large) when the Write Strategy is matched. FIG. 12 shows measurement results of jitter when recording according to the present invention.
The type C pit jitter is smaller than that in FIG. Therefore, according to the present invention, the characteristics of each disk can be maximized, and the occurrence of a reading error can be prevented.

Instead of detecting the length of pits or the like recorded on the optical disc and correcting the write strategy, a disc type identification signal is recorded in advance on an unrecorded optical disc, and the disc type is recorded. Optimal Write St for each
The rategy is stored in the memory, the identification signal is read when recording on the optical disc, and the corresponding Write Strate
gy can be read from the memory and set in the modulation rule correction means 36.

In the above embodiment, the case where the Write Strategy is corrected by detecting the pit length has been described.
The Write Strategy can be corrected by detecting the land length or detecting the pit length and the land length. Further, the present invention can be applied to a recording device for a rewritable optical disk such as a magneto-optical disk and a phase change optical disk, in addition to a write-once optical disk. In the case of a rewritable optical disk, the test signal can be erased later,
Any area can be used as a test area.

[0023]

As described above, according to the first aspect of the present invention, prior to the actual recording, a test signal is preliminarily recorded in the test area of the optical disk, and the portion is reproduced to reproduce the pit length. Write to reduce error or land length error or pit length and land length error
Since the strategy is corrected, errors in the pit length and land length and jitter can be reduced irrespective of the type of the disk, and the characteristics of the disk can be maximized to prevent a read error from occurring.

According to the second aspect of the present invention, the write strategy is corrected using the return light during the actual recording so as to reduce the pit length error, the land length error, or the pit length and land length error. So, Write St in real time
Rategy can be corrected. Therefore, even when the film formation state of the recording film is different between the inner circumference side and the outer circumference side of the same disk, it is possible to set the optimum Write Strategy at each recording position, and to maximize the characteristics of the disk,
The occurrence of a reading error can be prevented.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention.

FIG. 2 is a diagram showing a setting example of Write Sterategy on a time axis.

FIG. 3 is a waveform diagram showing Write Sterategy of laser power.

FIG. 4 is a waveform chart showing an example of a pit length measuring method.

FIG. 5 is a block diagram and an operation explanatory diagram showing another example of a pit length measuring method.

FIG. 6 is an operation waveform diagram showing still another example of the pit length measurement method.

FIG. 7 is a flowchart showing a procedure for correcting Write Sterategy using a test signal in the optical disc recording apparatus of FIG. 1;

FIG. 8 is a flowchart showing a procedure for correcting Write Sterategy in real time at the time of actual recording in the optical disk recording apparatus of FIG. 1;

FIG. 9 is a diagram showing a measurement result of a pit length error when recording is performed with Write Sterategy fixed by a conventional method.

FIG. 10 is a diagram showing a measurement result of a pit length error when recording is performed with Write Sterategy corrected according to the present invention.

FIG. 11 is a diagram showing a jitter measurement result when recording is performed with Write Sterategy fixed by a conventional method.

FIG. 12 is a diagram showing a measurement result of jitter when recording is performed with Write Sterategy corrected according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Optical disk 14 Optical head (recording and reproducing head) 16 Recording signal modulation means 36 Modulation rule correction means

Claims (2)

[Claims] 1. A mark length recording type optical disk recording apparatus for recording information on an optical disk by a combination of a pit length and a land length, wherein a predetermined pit length or land length or a predetermined pit length and land length to be formed. Recording signal modulation means for modulating the time axis of the recording signal or the time axis and the recording power in accordance with the rules of the following, and prior to the main recording, the recording apparatus is driven according to the test signal modulated by the recording signal modulation means, and the test signal is A recording / reproducing head for recording in a test area of the optical disc and reproducing the recorded test signal; and the recording so as to reduce jitter according to the test signal reproduced by the recording / reproducing head. Modulation rule correction means for correcting the modulation rule of the time axis used at the time of main recording of the optical disk in the signal modulation means Optical disc recording apparatus comprising comprises a. 2. A mark length recording type optical disk recording apparatus for recording information on an optical disk with a combination of a pit length and a land length, wherein a predetermined pit length or land length or a predetermined pit length and land length to be formed. Recording signal modulation means for modulating the time axis of the recording signal or the time axis and the recording power in accordance with the rules of the following, and during the main recording, the recording signal is driven by the recording signal modulated by the recording signal modulation means, and the recording signal is transmitted to the optical disk. And a recording / reproducing head for reproducing the return light from the optical disk at the time of recording, and a jitter thereof is reduced according to the recording signal represented by the return light reproduced by the recording / reproducing head. Modulation rule correction for correcting the modulation rule of the time axis used by the recording signal modulation means in real time during the main recording. Optical disc recording apparatus comprising; and a stage.