JPH0812744B2 - Optical information recording / reproducing device - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention has an optically detectable guide track,
In addition, information is recorded and reproduced on an optical recording disk in which the guide track is divided into a plurality of sectors in advance. Especially, a pulse train of a specific pattern is recorded for a defective sector and an unused sector, and the pulse train of the specific pattern is detected during reproduction. The present invention relates to an optical information recording / reproducing apparatus which discriminates this sector as a defective or unnecessary sector and prevents recording / reproducing.

As a conventional optical information recording / reproducing apparatus, for example, Japanese Patent Application No. 59-4341
It is shown in No. 5. Generally, since the recording wavelength of an optical recording disk is about 1 μm, a dropout of a reproduction signal is likely to occur due to a defect on the surface of the optical recording disk. Due to the occurrence of this dropout, the raw error rate of the optical recording disk can be secured only from 10 ^-4 to 10 ^-6 . Therefore, various error control techniques have been proposed to overcome this low error rate. For example, in the case of a non-rewritable optical recording disc, if data is recorded in a certain sector and then the data is judged to be error-correctable, a pulse train of a specific pattern is recorded in the defective sector and it is recorded in another sector. Record the data again. An operation in which a pulse train having a specific pattern is recorded in a defective sector and the data in that sector is not reproduced is called delete. Further, even if there is a dropout in which it is predicted that correct reproduction is impossible even if data is recorded in the information recording area of the unrecorded sector, it is similarly judged as a defective sector and deleted. FIG. 3 is a block diagram of an optical information recording / reproducing apparatus for improving the reliability of the optical recording disk by performing the conventional delete operation. Reference numeral 1 is a photodetector for detecting reflected light from the optical recording disk. Is. Reference numeral 2 denotes a focus control circuit, which uses a control error signal output from the photodetector 1 to focus and control the minute spot light on the surface of the optical recording disk. Reference numeral 3 denotes a tracking control circuit which works so that the minute spot light is controlled to follow the guide track. The reproduction signal 4 is output from the photodetector 1 and binarized by the waveform shaping circuit 5. The sector address to be recorded / reproduced by the binarized signal is detected by the sector detection circuit 6, and the CPU 7 takes in the sector address. When the CPU 7 coincides with the sector address to be recorded / reproduced, the recording gate generating circuit 8 outputs the recording gate to the modulator 9, and the recording signal 12 is transmitted to the semiconductor laser driving circuit 11 via the multiplexer 10. The semiconductor laser drive circuit 11 optically modulates the semiconductor laser 13 according to the recording signal. Data is recorded by irradiating the optical recording disk with this light modulated light. On the other hand, the recorded data is demodulated by the demodulation circuit 14 from the binarized reproduction signal output from the waveform shaping circuit 5. The dropout detection 15 detects a dropout in which it is determined that error correction cannot be performed as a result of demodulating the recorded data, and when error correction is impossible as a result of reproducing an unrecorded sector. If so, it is determined as a defective sector, and the delete code generation circuit 16 generates a pulse train code of a specific pattern. By such a delete operation, the delete code is recorded over the defective recording sector so that the data in the sector is not reproduced. In the case of an unrecorded sector where dropout exists, only the delete code is recorded. The delete code is composed of a pulse train of a specific pattern, but a pulse train sufficiently wider than the maximum inversion interval of the code of normal data is used so that it can be reliably distinguished from data. FIG. 4 shows the signal waveform of each part in FIG. FIG. 4 (a) shows the signal format of an area obtained by further dividing a specific track of the optical recording disk, that is, sector 19. Reference numeral 17 is a sector address in which a track address and a sector address are coded, and a sector detection 6 detects a designated sector. Reference numeral 18 denotes an information recording area, which shows how data is recorded. In b), an example of the pattern of the delete code is shown. Three repeating pulse trains of "0" and "1" are overwritten in the information recording area. The pulse "1" is the recording power state, the data in the overwritten information recording area is lost, and three pulse widths of the delete code "1" are written. The delete detection 20 surely detects the pulse width of "1" which is sufficiently wider than the maximum inversion interval of this data. For example, a section of pulse width "1" is counted by a reference clock signal or the like, and if it is a predetermined pulse width or more, it is identified as one pulse of delete code. In the pattern of b), three delete code pulses are detected and it is determined that the sector is deleted.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, in the configuration as described above, since the leading pulse of the delete code tends to be recorded narrower than a predetermined pulse width, a delete detection error occurs, and further, the focus at the time of recording the delete code. There was a drawback when the control and tracking control became unstable. First, the reason why the head pulse width is narrowly recorded will be described. The delete code is optically modulated by the semiconductor laser drive circuit 11 and applied to the optical recording disk. By the way, the semiconductor laser 13 is characterized in that its optical output-driving current characteristics fluctuate drastically due to temperature changes, so it is necessary to maintain a predetermined optical recording power. Therefore, for example, as shown in Japanese Patent Application No. 59-157805, the pin diode 22 is arranged adjacent to the light emitting surface of the semiconductor laser for optical power servo during optical recording, that is, during pulse modulation. That is, when the reproducing state is changed to the recording state, the value of the comparison reference voltage of the servo system is naturally changed. At this time, a transient response occurs depending on the frequency characteristic of the servo system. FIG. 4d) shows an optical output waveform when the optical power servo is switched as described above. FIG. 4 (c) shows a recording gate signal, which indicates a recording state at the "1" level. Reference numeral 23 represents a recording power level, and 24 represents a reproduction power level. The optical power servo in the recording state starts to be applied immediately after the light emission, that is, from the rising edge of the head pulse 21, and reaches a predetermined specified power level after a certain time has elapsed according to the frequency characteristics of the servo system. The time required to reach the predetermined level depends on the frequency characteristic of the servo system, but is limited to about several μs. Therefore, the leading pulse of the delete code does not record the required pulse width because the transient state of the servo system as shown in 25 occurs in the optical output. FIG. 4e) shows the waveform of the reproduced signal 4 from the optical recording disk recorded by the optical output signal as shown in d), and FIG. 4f) shows the waveform of such reproduced signal e. The signal waveform after is shown. As described above, the shaped binarized signal of f is counted as a "1" level pulse width with a reference clock or the like to determine whether it has a predetermined pulse width. Therefore, since the pulse width of the beginning of the delete code is narrower than the predetermined width, it is not determined in the delete detection 20 that the sector is deleted and a detection error occurs. Next, the reason why the focus control and tracking control become unstable during delete recording will be described. The pulse width of the delete code is set sufficiently wider than the maximum inversion interval of the data in order to surely distinguish it from the data, and it is considered that the pulse width of 5 to 10 μs is appropriate. If the repetition frequency of the data recording signal is sufficiently high as compared with the frequency characteristics of the focus control and tracking control, the servo system responds to the recording signal and the control does not become unstable. However, like the delete code, "0"
When the pulse of 0, that is, the state where the optical output is zero is generated for 5 to 10 μs, the focus error signal is g and the tracking error signal is h. It becomes unstable.

In view of such a point, the present invention records a delete code having an accurate pulse width without being affected by a transient response generated at the time of switching from reproduction to recording of an optical servo system, performs stable delete detection, and delete code This is an optical recording / reproducing apparatus capable of suppressing disturbances to the focus control and tracking control that occur during recording and maintaining stable control.

Means for Solving the Problems The present invention has means for recording / reproducing data sector by sector on an optical recording disk having an optically detectable guide track, and the guide track being divided into a plurality of sectors. "0" and "1" having a width wider than the maximum inversion interval of
And an optical information recording / reproducing apparatus for writing a pulse train in which a plurality of pulse trains are superposed in a "0" section of the pulse train in a recorded or unrecorded sector information recording area. Is.

With the above-described structure, the present invention terminates the transient response at the time of switching from the reproduction to the recording of the optical servo system in the first "0" section of the delete code, and the servo in the "1" section, that is, the delete code recording. It is possible to record with a sufficiently stable optical output. Therefore, it is possible to provide an extremely stable optical information recording / reproducing apparatus in which the pulse width of the first "1" section is recorded narrowly and a delete detection error does not occur. In addition, since the optical output level in the section of "0" does not become zero when the delete code is recorded, the disturbance of the recording signal to the focus error signal and the tracking error signal is reduced, and it is stable even while the delete code is being recorded. Focus control and tracking control can be performed.

Embodiment FIG. 1 shows a block diagram of an optical information recording / reproducing apparatus in an embodiment of the present invention. The same components as those in the conventional example shown in FIG. 3 are designated by the same reference numerals. As described in the conventional example, the reproduction signal 4 from the optical recording disk
Is subjected to waveform shaping by the waveform shaping circuit 5, the sector address to be recorded / reproduced is detected by the sector detection circuit 6, and the data is taken into the CPU 7. The CPU 7 triggers the recording gate generation circuit 8 in the section of the sector position. In the sector to be deleted, the recording signal 12 is sent by the multiplexer 10.
To the delete side. The recording gate is also input to the delete code generation circuit 16 and the superimposed pulse generation circuit 26. The superposition pulse is a logical sum 27 so that the superposition pulse is superposed on the section of "0" of the delete code, and becomes a recording signal. The superposition pulse is mainly used to terminate the transient response of the optical servo by the time the leading "1" of the delete code is input, and to control the optical output sufficiently stable in the "1" section. On the other hand, the semiconductor laser drive circuit 11 operates the optical servo system even during recording, that is, during pulse modulation, and controls the optical output of the semiconductor laser to the specified optical output level. The pulse-modulated optical output signal is a pin diode 22 placed close to the semiconductor laser.
The peak hold circuit 28 holds the peak value of the received pulse signal.

The held crest value is compared and output with the reference voltage 29, and the servo system is configured so that the specified light output level can be obtained even during recording. Therefore, the pulse train to be superimposed on the section of the delete code "0" may be set to a pulse width and a pulse interval sufficient for the peak hold circuit 28 to hold the peak value. According to another study, when the superimposed pulse is overwritten with the background data, the superimposed pulse "1" happens to coincide with the code "0" in the data,
It is necessary to avoid a superposed pulse pattern that causes a continuous level of "1" to be difficult to distinguish from the original "1" section of the delete code. Therefore, as the optimum pattern of the superposed pulse, it is necessary to select a pattern that has a pulse width that is as narrow as possible, a value that is sufficient for holding the peak value, and a pulse interval that is wide enough so that no "1" level continuity occurs. is there.

In order to avoid an increase in jitter due to the influence of the subtle characteristics of the recording power and the secondary distortion of the reproduction signal, the optical recording disk employs differential recording that records only the rising / falling edge information of the modulation code. There is. For example, the pulse width of the MFM code is T, 15T, 2T, and when differential recording is performed with this code and the recording efficiency is maximized, the pulse width on the optical recording disk surface is T / 2, and the pulse interval is T / 2 ~ 3T / 2 change. For example, in the differentially recorded data as shown above, the pulse width T / 2,
Even if a worst-case "1" level continuation occurs when superposed pulses with a pulse interval of 2T are overwritten, the interval is at most 3T / 2. If the pulse width of the delete code "1" is set to a multiple of 3T / 2, the delete detection error cannot increase due to the recording of the superimposed pulse even if there is an influence of jitter or the like. FIG. 2 is a diagram showing signal waveforms of respective parts in the configuration of FIG. FIG. 2 a) shows sector 19 and track address and sector address 17 in which sector address is coded.
6 is a format diagram showing a time relationship of the information recording area 18. FIG. In b), a recording signal is obtained by logically adding the superimposed pulse in the section of "0" of the delete code.

Reference numeral c) is a recording gate, and the optical power is controlled to the recording light level when the recording gate is at "1" level. d) is the recording signal waveform b)
7 shows an optical output waveform of the semiconductor laser 13 modulated by the.
As shown in 30, the transient response of the optical power servo is completed by the time the leading "1" pulse of the delete code rises due to the superimposed narrow pulse, and it is sufficient from the rising edge of the leading "1" pulse. It can be seen that the specified light output level has been reached. e) shows a reproduced signal after the delete signal of b) is overwritten on the data part, and f) shows a binarized output after waveform shaping 5. As can be seen from f), in the configuration of the conventional example, the pulse width of "1" at the beginning was narrowed due to the transient response of the optical power servo system, whereas according to the present embodiment, the predetermined delete code The pulse width has been detected. g) is a focus error signal, and h) is a tracking error signal. Unlike the conventional example, the state in which the optical power is zero level does not continue for a long time, and recording light becomes intermittent at the "1" portion of the superposition pulse. Therefore, a large disturbance does not occur in the tracking error signal h) and the focus error signal. Therefore, stable focus control and tracking control can be performed even at the time of delete recording by ORing the superposition pulse in the section of "0" of the delete code.

In this embodiment, a plurality of pulse trains are superposed on all the portions of the delete code "0", but even if a plurality of pulse trains are superposed only on the leading "0" portion, the optical power servo which is the first effect is obtained. It is quite possible for the transient response of the system to reach the specified light output level by the time the leading "1" level begins.

As described above, according to the present invention, by using the semiconductor laser drive circuit that controls the delete code, which is the identification code of the defective sector, to the specified output light level by applying the optical power servo even during recording. Even when writing to an optical recording disk, it is possible to record and reproduce without narrowing the pulse width at the beginning of the delete code due to the transient response of the optical power servo system, and extremely reliable delete detection is possible. . Further, it is possible to reduce the disturbance to the error signal of the focus control and the tracking control during the delete recording, and the stable operation of the control system is possible, which has a great practical effect.

[Brief description of drawings]

FIG. 1 is a block diagram of an optical information recording / reproducing apparatus according to an embodiment of the present invention, FIG. 2 is an operation waveform diagram of the same embodiment, FIG. 3 is a block diagram of a conventional optical information recording / reproducing apparatus, and FIG. [Fig. 4] is an operation waveform diagram in Fig. 3. 18 ... Information recording area, 19 ... Sector, 16 ... Delete code generation circuit, 26 ... Superposed pulse generation circuit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takashi Inoue 1006 Kadoma, Kadoma City, Osaka Prefecture, Matsushita Electric Industrial Co., Ltd. 56) References JP-A-57-143705 (JP, A) JP-A-55-108938 (JP, A) JP-A-55-8629 (JP, A)

Claims (1)

[Claims] 1. An optical recording disk having an optically detectable guide track, wherein the guide track is divided into a plurality of sectors, and information data is modulated by a modulator and converted into a recording code. Information data modulation / recording means for recording in the information recording area of the optical recording disk, information data reproducing / demodulating means for reproducing the recording code recorded on the optical recording disk to demodulate the original information data, and recording code for modulating the information data Pulse train of "0" level and "1" level each having a wider time width than the maximum pulse time width in which the level of "1" is continuous and the maximum pulse time width in which the level of "0" is continuous In addition, at the beginning of recording of this repeated pulse train, a delete code composed of a pulse train starting at "0" level is superposed on the area where the information data of the sector has been recorded. The delete code recording means for recording and the servo stabilizing superposition having a time width narrower than the pulse time widths of the "0" level and the "1" level of the delete code in the "0" level section of the delete code. An optical information recording / reproducing apparatus comprising: a superposition pulse recording means for superposing and recording a pulse on a delete code.