JPH0294113A - Recording method of optical information recording member - Google Patents

Abstract

PURPOSE:To improve the number of repetitive recording times of an optical disk by changing the recording timing of the recording signal pulse trains of the optical disk at every recording. CONSTITUTION:This recording member is constituted of the optical disk A which rotates, an optical system B for condensing laser light onto the optical disk A, an information recording section C for modulating laser light, and a reproduction control section E for controlling a light spot by reproducing the information from the optical disk A. The recording marks are formed in different positions on the recording medium even if the recording and erasing of the signals of the same patterns are repeatedly executed by changing the relative positional relation of the start point of the driving signal of the laser and the optical information recording member. The respective points on the recording medium, therefore, have average heat histories and the local distortions of amplitude can be eliminated. The number of the repetition of recording and erasing is improved in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a recording method for an optical information recording member for recording and erasing information on a rotating optical disk using laser light or the like.

2. Description of the Related Art Techniques for recording and reproducing information using laser light are already well known, and are currently being widely applied to document files and data files. In addition, research and development cases are being reported regarding rewritable recording systems with an erasing function.

One of these methods is a so-called phase-change optical disk that utilizes reversible state changes between amorphous and crystal or between crystal and crystal. The recording thin film used for this purpose has the characteristic that it takes an amorphous state or a crystalline state depending on heating and cooling conditions using laser light, and that the state changes reversibly. The amorphous state and the crystalline state have different complex refractive indices consisting of a refractive index n and an extinction coefficient k, and a signal is recorded using the resulting difference in transmittance or reflectance.

In order to realize these, recording power Pw and erasing power P
There is a method in which the recording medium-1- is irradiated with a laser beam modulated between two power levels of e (Pw>Pe) (Japanese Patent Application Laid-open No. 145530/1982).

That is, when a recording material is irradiated with a laser beam whose intensity is modulated according to a signal, even if the irradiated part was in either an amorphous or crystalline state before, the part irradiated with the recording power Pw becomes an amorphous state. Erase power P
The part irradiated with c is in a crystalline state. As a result, overwriting (overwriting 1-) is possible with one spot. Here, the state change between amorphous and crystal has been described, but the same characteristics can be obtained also in the state change between crystal and crystal by changing the amorphous state to a semi-stable crystal state.

Another method is magneto-optical recording. The principle is that when a laser beam is irradiated onto a magnetic thin film that is anisotropic in the thickness direction, the amount of deflection of the reflected light differs depending on the direction of magnetization (Kerr effect). This method reproduces the signal by detecting the difference in the amount of deflection.

In order to achieve these, the magnetic thin film is warped and magnetized in a certain direction, and then a magnetic field is applied externally in the opposite direction to the magnetization direction. Laser light whose power is modulated between power Pw and zero is irradiated. The temperature of the portion of the magnetic thin film irradiated with the light of the recording power Pw exceeds the Curie temperature, and the direction of magnetization is reversed.

As a result, a magnetization reversal pattern corresponding to the signal is recorded on the magnetic thin film. When erasing, a laser beam equivalent to the recording power PW is continuously irradiated while a magnetic field is applied from the outside.

Problems to be Solved by the Invention Recording is performed on an optical disk by irradiation with laser light modulated between two power levels.

However, when recording and erasing signals is repeated many times, the recording medium gradually deteriorates due to thermal history, and as a result, the amplitude of the reproduced signal tends to decrease. In particular, if a signal with a certain pattern is repeatedly recorded on the same location on a recording medium and then a signal with a different pattern is recorded, the amplitude of the signal will be distorted, and the process of demodulating the signal will cause data reading errors (focus errors). ).

The number of times this bit error occurs is significantly smaller than when different signals are repeatedly recorded.

This phenomenon occurs when comparing each point on a recording medium when the same pattern signal is repeatedly recorded, there are parts where strong laser light is concentrated and parts where only weak laser light is irradiated. For this reason, if the optical disc has a mixture of parts with different numbers of repetitions in the track direction, and different patterns of signals are recorded on the parts, depending on what kind of laser light irradiation the recording part has received previously, This is thought to be due to a difference in the reproduction amplitude of the recorded signal. That is, the reproduction amplitude iJ of the part where strong laser light was concentrated is small, and conversely, the reproduction amplitude iJ of the part where only weak laser light was irradiated is equal to the initial value. This difference in amplitude causes peak shift I when demodulating the data signal.
・This is thought to result in signal loss and bit errors. In actual recording, it is difficult to imagine recording exactly the same signal repeatedly. However, in the case of a data signal, even if the data value itself changes, the signals between data and the clock signal portion may have the same pattern. In view of this, an object of the present invention is to provide a method for increasing the number of times recording and erasing is repeated by improving the laser beam irradiation conditions.

Means for Solving the Problems A method for recording a signal on an optical information recording member-L having more than one state, or for recording a new signal while erasing an old signal. , the relative positional relationship between the starting point of the laser drive signal irradiated to the optical information recording section 10A and the optical information recording member is changed by one degree each time recording is repeated, in accordance with the information letter.

Effect By changing the relative positional relationship between the starting point of the laser drive signal and the optical information recording section 10A according to the present invention for each repeated recording, even when recording and erasing of the same pattern of signals is repeatedly performed. Recording marks are formed at different positions on the recording medium -1-. For this reason, each point on the recording medium can eliminate the average thermal history and local amplitude distortion.Therefore, the repeated life of the recording medium is improved.

EXAMPLE Hereinafter, a recording method for an optical information recording member according to an example of the present invention will be described with reference to the drawings.

FIG. 1a shows a Forman 1 signal generated from an optical disc, and FIG. 1b shows a timing chart of a recording signal used to demonstrate the present invention.

b indicates the reference gate of the signal to be recorded, which is obtained by synchronizing the data signal to be recorded with the format signal a of the optical disc. Further, C is a clock signal formed from a data signal to be recorded. d~ is a recording gate signal having a certain time delay from the reference game) b, where d is IT, e is 2T, r is 3T, and k is 8T. In this way, a total of eight types of gates are provided at IT intervals. Conventionally, recording has been performed using only this b gate. In the method according to the present invention, this recording gate is performed not only in one pattern but also by selecting one of a plurality of gates 1- having different delay times with respect to the reference gate b when recording a signal. That is, changing the gate delay time corresponds to changing the relative position of the optical disk and the laser drive signal used for recording. According to this method, the same pattern of signals is repeated every time.

Even if a mark is recorded at a slightly different position each time on an actual optical disc, the mark is formed at a slightly different position each time. As a result, each point on the repeatedly recorded track -1- is irradiated with approximately the same amount of laser light, resulting in a --like thermal history. For this reason,
Even if the amplitude decreases due to repetition, since the amplitudes of the signals reproduced from adjacent marks are the same, peak shifts in the reproduced waveform and signal dropouts are unlikely to occur, and no Pip-1 error occurs.

FIG. 2 is a block diagram showing an example of an optical disk recording apparatus using the zero method. This device consists of a rotating optical disc A, an optical system B that focuses laser light onto the optical disc A,
It consists of an information recording section C1 for modulating laser light, a reproduction control section E for reproducing information from the optical disk A and controlling the optical spot.

The optical disc A is composed of a substrate 1 and a recording thin film 2 on the substrate 1. As the substrate 1, resin such as polymethyl methacrylate (PMMA) or polycarbonate (11Pc) or glass can be used.

The recording material 3, which records signals using phase change caused by light irradiation, includes GeTc, GeTc, amorphous-crystal phase change, etc.
Ge5b2Tc, Ge2Sb2 T5, InSe series,
In5eTffiCo series, Ge5nTcAu series, Ge
S b T e S e series, 5eSnTcO series, 5e
A TeS-based material or the like can be used. Further, as the phase change material between crystals, 1nsb type, AgZn type, etc. can be used. Recording materials for magneto-optical recording include TbFe
Examples include C0GdTbFe.

A data signal to be recorded on the optical disc is led to the information recording section C and is first temporarily stored in the buffer memory 3. The data in the buffer memory 3 is read out in synchronization with the gate I signal output from the recording gate generator 4, and is modulated by a modulation circuit 5, for example, by 27. This modulation circuit 3 not only performs 2-7 modulation of the recording data, but also generates sector signals, synchronization signals, cue signals, etc. according to a fixed format, and inserts them into the modulation data.

The drive circuit 6 generates a pulse having a waveform corresponding to the 2-7 modulated data in synchronization with the write gates 1 to 1 from the recording gate generator 4. Note that the gate signal from the recording gate generator 4 is subjected to a random time delay by a gate delay circuit 7.

The optical system I3 used a semiconductor laser 8 with a wavelength of 780 nm as a light source. The light from the semiconductor laser 8 is turned into parallel light by the collimator lens 9, and the light from the semiconductor laser 8 is converted into parallel light by the collimator lens 9.
The wavelength limit of 1 μm is transmitted through the 0.1/4 wavelength plate 11 and onto the recording thin film 2 of the optical disc A by the objective lens 12.
The light is focused on a spont diameter of . In addition, recording thin film 2
The reflected light from the glass passes through the objective lens 12 and 1/4 wavelength plate 1 again.
1, is reflected by the deflection heam splinter 10, and is received by a photodetector 13. The signal photoelectrically converted by the photodetector 13 is amplified by the preamplifier 14 of the reproduction control section E.

The playback/control unit E converts the low frequency component of the signal from the preamplifier 14 into a control signal using the focus/ranging control unit 15, drives the voice coil 16 that supports the objective lens 12, and drives the voice coil 16 that supports the objective lens 12. Perform second spot focusing and I-racking. On the other hand, the demodulation circuit 16 demodulates the data signal from the mark formed on the optical disc A using the high frequency component of the signal from the preamplifier 14. The reproduced data demodulated by this is temporarily stored in the Hahua memory 17. The optical disc is played back by reading out the data stored in the buffer memory 17.

FIG. 3 is a configuration diagram showing an example of the second gate delay circuit 7. A reference gate signal (b) and a clock signal (C) generated by the recording gate I generator 4 based on the data signal and the formant signal of the optical disc -J- are applied to the shift register 18. Eight types of signals (d) to (k) are generated with time delays in IT increments in the Schif I/Regisf. Note that the respective signal waveforms are shown in FIG. Also,
The gate signal is applied to the counter 19, and a binary count signal (ri~(n)) is output.

In the selector 20, the gate signal of the address specified by the signal from the counter 19 is selected, that is, one of the signals (d) to (2) from the shift register 1 is recorded as the gate signal (0). Output. As a result, recording gates with eight types of time delays are obtained compared to the initial recording game (b). Although an 8-bit system has been described here, the number of focuses, ie, the number of delay gate patterns, can be increased or decreased as necessary.

In order to clarify the effect of actually delaying the recording gate, we showed the correlation between the delay time width of the recording gate and the maximum number of repetitions without causing a bit error when repeatedly recording on an optical disk. It is a diagram.

The optical disc A had a structure in which the substrate 1 was made of polycarbonate resin with guide tracks for address signals and tracking provided on the surface, the recording thin film was made of GeSb2Te, and the recording thin film was provided with protective layers made of ZnS on both sides. The optical disc was rotated at a speed such that the linear velocity in the recording section was 10 m/s. The data signal modulation method used for recording was 27 RL L code focus position modulation recording, and the transfer rate was 5 Mbps. In addition, Reed-Solomon code was used as the signal error correction method.

Recording (overwriting!) on the optical disc is performed by modulating the power of the semiconductor laser 8 between recording power and erasing power according to the data signal. In addition, each power for optical disc "2" is recording power of 16 mW,
Erase power is 8mW, playback power is 1. It was set as mW.

Recording was performed repeatedly under the above recording conditions.

Two types of data signal patterns to be recorded are set, and after the first pattern signal is repeatedly recorded 1000 times, the second pattern signal is recorded, and then the reproduced signal by the recording mark on the optical disk and the second pattern signal are combined. Focus error is detected by comparison. This 1ooo cycle of recording and bit error measurement is applied to the playback signal.
Continue until an error is detected. At this time, the recording gate changes for each repetition according to the pattern generated by the gate delay circuit. Further, the delay time interval of each game I-pattern was set to the clock cycle IT of the data signal to be recorded. There are 20 types of gate patterns: 4 types from IT to 4T when the maximum gate delay time is 4T, and 20 types from IT to 20T when the maximum gate delay time is 20T. Figure 4 shows the results of measurements under the above conditions.As the gate delay time increases, the number of repetitions increases, and when the delay time i+ exceeds 16T, it reaches a constant value. ing.

By randomly changing the timing of recording data signals in this way, it is possible to average the thermal history at each position on the recording thin film. Moreover, the tendency of averaging becomes more pronounced as the delay time width increases.

The delay time 16T at which the number of repetitions saturates is 27 RL
Since I-=maximum level inversion of y-do corresponds to 4iB with an interval of 4T, it is considered that the laser beam irradiation history at each point on the recording track is averaged.

Please note that this measurement system and the rotation of the disk must be thick.
It is included. In this system with large sinter,
Similar effects can be obtained even if the delay time is 16T or less. On the other hand, in a system with small jitter, it is necessary to further increase the amount of delay. In addition, in this measurement system, the pitch of the gate delay time was set to IT, but the shortest mark interval of the 2-7RLL code was 1.5"F, and the jitter of the measurement system was 0.
When the temperature is 5T or less, a minute area with little light irradiation history is formed around one recording mark. To accommodate this, an even shorter gate delay time pinch, for example 0.
It is better to use 5T or 0.25T.

In this embodiment, the results are for the 2-7 RL L code modulation method, but the wooden sword method can be similarly applied to other modulation methods. For example, even in this case, if the maximum gate delay time is D and the maximum signal inversion interval of the modulation method is Tmax, the gate delay time may be set so that the relationship Dmax≧4Tmax holds. Furthermore, the wooden sword method can be similarly applied to other phase change type recording media and magneto-optical recording media.

Effects of the Invention As described above, by changing the recording timing of the recording pulse train of the optical disc each time recording is performed, it is possible to increase the number of times of repeated recording on the optical disc.

[Brief explanation of drawings]

FIG. 1 is a conceptual diagram showing a recording method in an embodiment of the present invention, FIG. 2 is a block diagram of a recording/reproducing apparatus using a wooden sword type, FIG. 3 is a block diagram showing an example of a gate delay circuit, and FIG. The figure is a characteristic diagram showing the relationship between the delay time width of the recording gate and the number of repetitions. a... Optical disc format signal, b...
...Reference gate signal, C...Clock signal, d, ef, k...Gate delay signal. Name of agent: Patent attorney Shigetaka Awano and X others Figure 1

Claims (3)

[Claims] (1) A method for recording a signal on an optical information recording member having two or more optically distinguishable states, the method comprising: recording a driving signal of a laser that irradiates the optical information recording member in accordance with the information signal; A method for recording an optical information recording member, characterized in that the relative positional relationship between a starting point and the optical information recording member is changed for each repeated recording. (2) As a method of changing the relative positional relationship between the starting point of the laser drive signal and the optical information recording member for each repeated recording, a delay circuit is provided between the information signal and the laser drive circuit, and the delay circuit 2. The recording method for an optical information recording member according to claim 1, wherein the delay time is changed. (3) The method for changing the relative positional relationship between the starting point of the laser drive signal and the optical information recording member for each repeated recording is characterized in that the method changes the relative positional relationship between the starting point of the laser drive signal and the optical information recording member with reference to a clock signal of the information signal (1). ) or the recording method for an optical information recording member according to any one of (2). (4) In a method of changing the relative positional relationship between the starting point of a laser drive signal and the optical information recording member for each repeated recording, the relative positional relationship between the starting point of the driving signal and the optical information recording member is changed. Claim (1) or (2) characterized in that, where the maximum value of the amount is Dmax and the maximum level inversion interval of the modulation method of the information signal is Tmax, there is a relationship of Dmax≧4Tmax.
) A recording method for an optical information recording member according to any one of the above.