JP2002342928A - Information recording and reproducing device, method therefor, and information recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the best signal quality in both of lands and grooves during recoding and reproducing. SOLUTION: The recommended shift quantities of pulses for recording recorded as prepit on an optical disk 61 are read at the time of insertion of a recording device (step S2). The shift quantities between the top pulse start time and terminal pulse end time of the marks above the 3T marks, 4T marks, 5T marks and 6T marks, are varied independently by ±1 ns each with the shift quantities as reference and are recorded in the lands and grooves. A bit error rate is measured and the shift quantities at which the values are minimized at each marks are extracted discretely by the lands and the grooves (steps S4 to S8).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of recording and erasing information by repeatedly changing the optical characteristics of a recording layer by irradiating a laser beam, an electron beam or the like with a change in an atomic arrangement. Recording / reproducing apparatus, information recording / reproducing method, and information recording medium for reproducing information by detecting a change in dynamic characteristics.

[0002]

2. Description of the Related Art Recordable and erasable information recording media include:
For example, it has a structure including a substrate 1, a recording layer 2, a protective layer 3 made of an inorganic dielectric, and an organic protective film 4 shown in FIG. Substrate 1
Is made of glass or a plastic material (for example, polymethyl methacrylate resin or polycarbonate resin), and the recording layer 2 and the inorganic dielectric protection layer 3 can be formed by a deposition method such as vacuum evaporation and sputtering. The organic protective film 4 is made of an ultraviolet curable resin or the like. Using such an information recording medium, information can be recorded / erased as follows, for example.

[0003] First, a light beam having a beam spot diameter larger than that at the time of information recording / reproducing is moved from the inner circumference to the outer circumference of a rotating information recording medium, and is irradiated onto the entire recording surface of the information recording medium, thereby recording. The layer 2 is heated to a state of high crystallinity (a state where atoms are relatively correctly arranged, hereinafter referred to as a crystalline state). This light beam irradiation is performed before the information recording medium is shipped from the factory.

When writing information on an information recording medium, a short intense pulse light for writing information is irradiated to heat and cool the recording portion. Then, the pulsed light irradiation part is in a state in which the crystallinity is reduced (a state in which the atomic arrangement is disordered, hereinafter, referred to as amorphous). Since the structure of the atomic arrangement is different between the crystalline state and the amorphous state, the optical properties (transmittance and reflectivity) change and information can be recorded. In this way, the written information can be erased by irradiating the recording section with a weak pulse light and heating and cooling. This is because the recording unit returns to the original crystalline state.

Further, by using a light beam in which a strong continuous pulse is superimposed on a weak continuous light beam as shown in FIG. 8, the previously formed recording portion (amorphous state) is erased (crystalline state). At the same time, a so-called overwrite in which a new recording portion is formed can be realized. As a result, a strong (writing) laser is irradiated at the data "1",
By irradiating a weak continuous (erasing) laser at data "0", data "1" can be recorded as amorphous.

An optical recording system actually used for information processing stores information in fixed chunks called sectors.
You are interacting with the outside world. Generally, as shown in FIG. 9, the sector is divided into a header section 51 and a recording area section (user data section) 58. The header section 51 is an area including a synchronization signal, physical address information (address section) of the sector, an error correction section, and the like. As shown in FIG. 10, the header section 51 is embedded in the substrate as pits, and generally has a VFO 1 and an address mark, I, which are synchronized with the PLL.
D and CRC.

FIG. 11 is a diagram showing a configuration of an optical information recording medium (optical disk). As shown in this figure, in the land / groove recording, sectors are arranged in the land portion and the groove portion.
This is a method in which data can be recorded on the land and groove. A conventional general example is a single spiral configuration in which lands / grooves are connected continuously. As shown in FIG. 12, the header section 51 of the land sector / groove sector is pre-formatted at the center of the land / groove. With this configuration, the header portion 51 can be detected even when tracking is performed on a land track or a groove track. As can be seen from FIG. 12, for example, land sector # (m
+ 2N-1) tracking is followed by groove sector #
The tracking becomes (m + 2N), and the land / groove is tracked continuously.

When a mark (data "1") is recorded on an optical disk by using pulse light of a laser beam, heat generated by a mark recorded immediately before is diffused to a recording portion of a mark to be recorded next. The temperature of the recording section differs depending on the length of the space between the recording section and the mark recorded immediately before. The longer the space, the lower the temperature of the recording section. If the temperature at the start of recording is different,
The recording start position may be shifted. The longer the space, the more the recording position shifts backward. Therefore, 4.7 GBD
As a recording method of the VD-RAM, when a mark is recorded by a strong pulse light for writing information, the recording start timing and the recording end timing of the mark are changed by a combination of the length of the mark and the length of the space before and after the mark. The signal quality is improved by using a method of recording (by changing the shift amount).

[0009]

As described above, 4.
The 7 GB DVD-RAM uses a land / groove recording method. Lands and grooves have a relationship between mountains and valleys,
At the time of recording, the appearance of heat generation and diffusion are different. for that reason,
When recording is performed by changing the start and end positions of the recording mark described above by a combination of the recording mark and the length of the front and rear spaces, the recording start and end positions are different between the land and the groove. Therefore, if the same shift amount is used for the recording start and end positions in the land and the groove of the optical recording medium, it is impossible to obtain an optimum, that is, a minimum bit error rate for both, and an average bit error rate for both is obtained. It's just

Also, due to variations in the optical recording medium during manufacture and mechanical fluctuations when the optical recording medium is inserted into a recording apparatus, the optimum shift amount of the recording start and end positions may differ for each optical recording medium and for each insertion. There is. Therefore, if the same shift amount is applied to all the optical recording media, the bit error rate may be deteriorated and the reliability and signal quality may be impaired.

Accordingly, an object of the present invention is to obtain the best signal quality in both lands and grooves during recording and reproduction. It is another object of the present invention to absorb variations in quality among optical recording media and mechanical fluctuations during insertion, and to always obtain the best signal quality during recording and reproduction.

[0012]

As described above, the land,
The problem of the bit error rate deteriorating when the same combination table is used because grooves generate and diffuse heat differently is solved by having two types of land combination table and groove combination table. Also, the problem that the optical recording medium varies in manufacturing and the shift amount of the recording start / end position is different every time the recording device is inserted is caused by changing the combination table in the trial writing area every time the optical recording medium is inserted. The problem can be solved by recording, reproducing, and extracting the optimum combination table.

In the 4.7 GB DVD-RAM, the combination table described above is recorded in the lead-in portion on the substrate as pre-pits. This value is read when the optical recording medium is inserted into the recording device. Based on this, the shift amount of the start pulse start time and the end pulse end time of the 3T mark, 4T mark, 5T mark, and 6T or more marks are set to 1
Recorded in land and groove with variable independently for each ns
The bit error rate is measured, and the shift amount that minimizes this value for each mark is extracted separately for the land and the groove. Further, the shift amount of the land portion and the groove portion obtained by recording once is recorded on the information recording medium as a look-up table, and further optimization is performed by using this table next time, so that higher reliability is obtained. Is obtained.

[0014]

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

FIG. 1 is a block diagram showing a configuration of an optical disk apparatus to which the present invention is applied.

A land track and a groove track are formed spirally on the surface of an optical disk 61 as an optical recording medium. The disk 61 is driven to rotate by a spindle motor 63.

Recording and reproduction of information on and from the optical disk 61 are performed by an optical pickup 65. The optical pickup 65 is connected to a sled motor 66 via a gear, and the sled motor 66 is controlled by a sled motor control circuit 68.

A speed detection circuit 69 is connected to the sled motor control circuit 68, and a speed signal of the optical pickup 65 detected by the speed detection circuit 69 is sent to the sled motor control circuit 68. A permanent magnet (not shown) is provided at a fixed portion of the thread motor 66. When the drive coil 67 is excited by the thread motor control circuit 68, the optical pickup 65 moves in the radial direction of the optical disk 61.

The optical pickup 65 is provided with an objective lens 70 supported by a wire or a leaf spring (not shown). The objective lens 70 can be moved in the focusing direction (the direction of the optical axis of the lens) by driving the drive coil 72, and can be moved in the tracking direction (the direction orthogonal to the optical axis of the lens) by driving the drive coil 71. It is.

The laser drive circuit 75 of the laser control circuit 73
As a result, laser light is emitted from the semiconductor laser diode 79. The laser light emitted from the semiconductor laser diode 79 is supplied to the collimator lens 80, the half prism 8
1. The light is irradiated onto the optical disk 61 via the objective lens 70. The reflected light from the optical disk 61 is
0, a half prism 81, a condenser lens 82, and a cylindrical lens 83, the light is guided to a photodetector 84.

The photodetector 84 includes a four-divided photodetection cell 84.
a to 84d. Output signals of the photodetection cells 84a to 84d are supplied to differential amplifiers OP1 and OP2 via current / voltage conversion amplifiers 85a to 85d and adders 86a to 86d.
Supplied to

The differential amplifier OP2 includes adders 86a, 86
A signal related to the focus point is output according to the difference between the two output signals b. This output is output from the focusing control circuit 87.
Supplied to The output signal of the focusing control circuit 87 is supplied to the focusing drive coil 72. As a result, control is performed such that the laser beam is always just focused on the recording film of the optical disk 61.

The differential amplifier OP1 includes adders 86c and 86
A track difference signal corresponding to the difference between the two output signals is output. This output is supplied to the tracking control circuit 88. The tracking control circuit 88 generates a track drive signal according to the track difference signal from the differential amplifier OP1.

The track drive signal output from the tracking control circuit 88 is applied to the drive coil 7 in the tracking direction.
1 is supplied. The track difference signal used in the tracking control circuit 88 is transmitted to the thread motor control circuit 68.
Supplied to

By performing the focusing control and the tracking control, the sum signal of the output signals of the photodetection cells 84a to 84d of the photodetector 84, that is, the addition signal for adding both output signals of the adders 86c and 86d. The change in the reflectance from the pits formed on the tracks of the optical disk 61 corresponding to the recorded information is reflected in the output signal of the optical unit 86e. This signal is supplied to the data reproducing circuit 78. The data reproduction circuit 78 reproduces the recorded data based on the reproduction clock signal from the PLL circuit 76.

When the objective lens 70 is controlled by the tracking control circuit 88, the objective lens 70 is
The sled motor 66, that is, the optical pickup 65 is controlled so as to be located near the center position of the inside.

The motor control circuit 64, thread motor control circuit 68, laser control circuit 73, PLL circuit 76, data reproduction circuit 78, focusing control circuit 87, tracking control circuit 88, error correction circuit 62, etc.
9 is controlled by the CPU 90. CPU 90
Controls the recording / reproducing apparatus comprehensively according to an operation command provided from the host device 94 via the interface circuit 93. The CPU 90 uses the RAM 91 as a work area and performs a predetermined operation according to a program including the present invention recorded in the ROM 92.

FIG. 2 shows an example of the semiconductor laser control circuit 73. A phase change optical disk requires three levels of light modulation: recording power, erasing power, and reproducing power. First, the operation at the time of writing and erasing will be described. When the header section 51 is detected from the reproduction signal and the R / W signal 100 becomes LOW and is input to the multiplexer 105, the reproduction / erase laser drive current circuit changeover switch 110 selects the erase laser drive current circuit 107. At the same time, when the user data signal 101 is input to the data conversion ROM 102, (8, 16) modulated data is output from the data conversion ROM 102. Based on this data, the CLK generator 10
The data is converted into serial data by a parallel / serial (P / S) conversion circuit 104 in synchronization with the channel clock signal output from 3 and input to a multiplexer 105.

Each output laser power level is set in advance in the write laser drive current circuit 106 and the erase laser drive circuit 107, and the write laser drive current switch 109 is synchronized with a signal output from the multiplexer. By switching ON / OFF, the write laser drive current flows into the adder 111 and is added to the erase power drive current. And the amplifier 112
The laser beam is amplified by the laser diode 79 and output to the laser diode 79. The laser diode 79 irradiates the laser with the set power level and the set time.

At the time of reproduction, when the R / W signal 100 becomes HIGH and is inputted to the multiplexer 105, the reproduction / erasing laser driving current circuit changeover switch 110 selects the reproduction laser driving current circuit 108 and the laser diode 7
9 reproduces laser power for reproduction.

FIG. 3 shows a signal waveform for information recording.
(8, 16) For example, widths 11T, 5T, 3T of the NRZI signal of FIG. 3A generated based on the modulated data
On the other hand, an optical pulse waveform for driving the laser diode 79 is generated as shown in FIG. Tsfp is NRZ
Start pulse start time for rising of I signal, Tm
p is each pulse width of the continuous pulse, Tslp is the end pulse start time with respect to the reference clock, Tlp is the end pulse width,
Telp is the end pulse end time with respect to the reference clock.

In the case of a DVD-RAM, a land / groove recording method is used. The land and the groove have a relationship of a mountain and a valley, and generate and diffuse heat differently during recording.
That is, even if a plurality of marks are recorded on lands and grooves at exactly the same timing and laser power, the shapes of the recorded marks are slightly different. For example, Japanese Patent Laid-Open No. 9-1
Japanese Patent No. 6965 discloses a technique for setting an optimum recording power for all positions on a disk for each of a land and a groove.

According to the present invention, the optimum values of the mark start and end positions, for example, are detected for lands and grooves, and information is recorded using the optimum values to obtain the best signal quality in both lands and grooves. I have.

FIG. 4 is a flowchart showing the operation of the present invention. After the optical disc is mounted on the recording device, a look-up table relating to the shift amount recorded in advance in the lead-in portion of the optical disc is read, and the start pulse start time Tsfp and the end pulse end time Telp described in the look-up table are read out. Tsfp0, T respectively
elp0 and N = 3 (steps S1 to S3).

FIG. 5 shows an example of this look-up table. The head pulse start time Tsfp will be described. For example, when the mark to be recorded is 3T, the space length with the mark recorded immediately before is 8 ns when the space length is 3T, 8 ns when the space length is 4T, 8 ns when the space length is 5T, and 7 ns when the space length is longer than 6T.
ns (shift amount) is set. The end pulse end time Telp is set similarly.

Next, using the recording waveform information, four or more tracks are recorded in the test writing area using the recording waveform created for the 3T mark (N = 3). Then, the center land and groove tracks are reproduced, and the bit error rate (hereinafter, BER) is measured, and each is stored.
Next, four Tsfp0 (8, 8,
8, 7 ns) plus -1 ns, and record and reproduce in the same manner. E. FIG. R. Is measured. Next, Tsfp of 3T mark
The same measurement is performed by adding 1 ns to 0. And three B. of groove. E. FIG. R. Are compared and the minimum added value is adopted. The same applies to the land (step S
4, S5).

Next, for Telp0, similarly, 0,-
Recording / reproducing with a recording waveform to which 1, 1 ns is added; E. FIG. R.
The measurement is performed, and the minimum added value is adopted for the groove and the land separately (steps S7 and S8). This is performed for the 4T mark, the 5T mark, and the mark of 6T or more.

Finally, the Tsf detected as described above is used.
Using the optimum shift amount of p and Telp, an optimum shift amount table for each land and groove is created as a second look-up table, and is recorded on the optical disk (step S11). FIG. 6 shows an example of this optimum shift amount table.

As described above, by recording the optimum shift amounts for the lands and grooves extracted in the present invention on the information recording medium, the second shift amount can be obtained when the disc is inserted again.
By using the lookup table, land,
The groove is optimized, and more reliable information is obtained.

As a result of the evaluation of recording / reproducing on 1000 tracks, B.C. E. FIG. R. Is 5 ×
It was improved from 10 ^-4 to 1.2 * 10 ^-4. Even if the disk is repeatedly attached and detached, a large B.I. E. FIG. R. There was no difference, and there was an improvement effect.

As described above, the present invention provides high quality and high reliability by having the shift amount of the recording waveform of the mark independently for the land and the groove for the combination of the mark and the space before and after the mark. It is possible to provide a phase change optical disk system having the same.

Further, it is possible to provide a phase change optical disk system having high quality and high reliability by absorbing variations in disk manufacture and mechanical fluctuations at the time of disk insertion.

Furthermore, if the shift amount of the land portion and the groove portion obtained by recording once is recorded on the information recording medium as a look-up table, further optimization is performed by using this table next time. Higher reliability is obtained.

In the above-described embodiment, an example has been described in which the optimum shift amounts of the start pulse start time Tsfp and the end pulse end time Telp have been obtained. You can ask.

[0045]

According to the present invention, it is possible to provide a phase change optical disk system having high quality and high reliability.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an optical disk recording device to which the present invention is applied.

FIG. 2 is a block diagram showing a general configuration of a semiconductor laser control circuit.

FIG. 3 shows a signal waveform for information recording.

FIG. 4 is a flowchart showing the operation of the present invention.

FIG. 5 is a look-up table regarding a shift amount of an information recording signal.

FIG. 6 is a look-up table according to the present invention relating to a shift amount of an information recording signal.

FIG. 7 is a sectional view showing the structure of an information recording medium on which recording and erasing can be performed.

FIG. 8 is a general example of a laser drive current waveform.

FIG. 9 shows an example of a general intra-sector format.

FIG. 10 is a diagram showing a configuration of a header unit.

FIG. 11 is a diagram showing a configuration of an optical information recording medium.

FIG. 12 is a diagram showing an arrangement of a header section and land / groove sectors.

[Explanation of symbols]

61 optical disk, 63 motor, 70 objective lens
71, 72: lens drive coil, 79: laser diode, 80: collimator lens, 81: half prism, 82: condenser lens, 83: cylindrical lens,
84a to 84d: photodetection cells, 85a to 85d: current /
Voltage conversion amplifiers, 86a to 86d: adders, 106: writing laser drive current circuit, 107: erasing laser drive circuit, 108: reproduction laser drive current circuit, 109
, Writing laser drive current switch 110, read / erase laser drive current circuit changeover switch 111
... adders.

Claims (10)

[Claims] 1. A method for recording a mark by irradiating an intensity-modulated light beam to a phase-change optical disk having a land portion and a groove portion as recording tracks, and recording information as a combination of a mark length and a space length, The start pulse start time of the recording waveform for recording a mark is varied according to the combination of the length of the mark and the space before the mark, and the end time of the end pulse of the recording waveform for recording the mark is Variably depending on a combination of the length of the mark and the space behind the mark, and the variable amounts of the start and end times of the recording pulse are individually set for the land portion and the groove portion. The information recording method characterized by the above-mentioned. 2. The information recording method according to claim 1, wherein said mark, said front space, and said back space are each one of 3T, 4T, 5T, and 6T or more. 3. A method for recording a mark by irradiating an intensity-modulated light beam to a phase-change optical disc having a land portion and a groove portion as recording tracks, and recording information as a combination of a mark length and a space length, A first look-up table for changing a start time of a first pulse and an end time of an end pulse of a recording waveform for recording the mark is read according to a combination of a mark and a length of a space before and after the mark. Recording and reproducing the mark on the land portion and the groove portion using the recommended value described in the first lookup table and the value obtained by changing the recommended value, and changing the recommended value and the recommended value The optimum value having the smallest bit error rate among the values obtained is detected for the land portion and the groove portion, and the mark and the mark A second look-up table describing the optimum values of the start and end times is created according to the combination of the lengths of the front and rear spaces, and information is recorded on the optical disc with reference to the second look-up table. An information recording method comprising a step. 4. A method for recording a mark by irradiating an intensity-modulated light beam to a phase change optical disk having a land portion and a groove portion as recording tracks, and recording information as a combination of a mark length and a space length, A first look-up table previously recorded as pre-pits on the optical disc is read when the optical disc is inserted into the information recording apparatus, and a 3T mark is recorded based on a recommended value described in the first look-up table. Start time of first pulse of waveform,
The recording, reproduction and bit error rate measurement are repeated while varying the end pulse end time, and the optimum variable amount that minimizes the bit error rate is detected. Similarly, the recording waveforms of marks of 4T, 5T, 6T or more are similarly recorded. , Detecting an optimum variable amount that minimizes the bit error rate, and creating a second lookup table describing the optimum variable amount detected for the recording waveform of the mark of 3T, 4T, 5T, 6T or more. And a step of recording information on the optical disk with reference to the second lookup table. 5. The information recording method according to claim 3, further comprising a step of recording the second look-up table on the optical disk. 6. The information recording method according to claim 5, further comprising the step of updating said second look-up table each time said optical disk is inserted into a recording device. 7. A recording apparatus for recording a mark by irradiating an intensity-modulated light beam onto a phase change optical disk having a land portion and a groove portion as recording tracks, and recording information as a combination of a mark length and a space length. First variable means for varying a start pulse start time of a recording waveform for recording a mark in accordance with a combination of the length of the mark and a space before the mark; and a recording waveform for recording the mark. And second variable means for varying the end time of the end pulse of the mark according to the combination of the length of the mark and the space behind the mark. The variable amount of the start and end times of the recording pulse is An information recording device, wherein the information recording device and the groove portion are independently set. 8. A recording apparatus for recording a mark by irradiating an intensity-modulated light beam onto a phase-change optical disk having a land portion and a groove portion as recording tracks, and recording information as a combination of a mark length and a space length. A first look-up table for changing the start time of the head pulse and the end time of the end pulse of the recording waveform for recording the mark according to the combination of the length of the mark and the space before and after the mark. Reading means for reading; first recording means for recording the mark in the land portion and the groove portion using a recommended value described in the first lookup table and a value obtained by changing the recommended value; The mark recorded by the first recording unit is reproduced, and the bit error rate among the recommended value and the value obtained by changing the recommended value is the highest. Detecting means for detecting the optimum value for the land portion and the groove portion; and, based on a combination of the length of the mark and the space before and after the mark, the optimum value of the start and end times detected by the detecting means. And a second recording unit that records information on the optical disk with reference to the second lookup table created by the creating unit. Information recording device. 9. A recording apparatus for recording a mark by irradiating an intensity-modulated light beam to a phase change optical disk having a land portion and a groove portion as recording tracks, and recording information as a combination of a mark length and a space length. Reading means for reading a first look-up table previously recorded as pre-pits on the optical disc when the optical disc is inserted into an information recording device; and a reference value based on a recommended value described in the first look-up table. The start pulse start time of the 3T mark recording waveform,
A first detecting means for repeating recording, reproduction, and bit error rate measurement while varying the end pulse end time, and detecting an optimal variable amount that minimizes the bit error rate; and 4T, 5T, 6T or more marks. As for the recording waveform, similarly to the first detecting means, a second detecting means for detecting an optimum variable amount at which the bit error rate is minimized, and the 3T, 4T by the first and second detecting means. , 5
T, creating means for creating the optimum variable amount detected for the recording waveform of the mark of 6T or more as a second look-up table, and referring to the second look-up table created by the creating means, An information recording apparatus, comprising: recording means for recording information on the optical disc. 10. A look-up table for varying a start time of a first pulse and an end time of an end pulse of a recording waveform for recording the mark in accordance with a combination of a mark and a length of a space before and after the mark. Wherein the land and the groove are individually recorded in advance as pre-pits.