JP2006294243A - Method and device for recording and reproducing information - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that improvements on recording signal quality and stability at the time of repeating overwrite and improvements on reliability and versatility can not be attained. <P>SOLUTION: In PWM (pulse width modulation) recording, a recording wave in recording and re-writing a 0-signal of a modulated signal width nT is a continuous wave at a power level(e) and a recording pulse train in recording and re-writing a 1-signal of the modulated signal width nT is constituted of a pulse part (fp) of a time width (x) and a value (a), a multi pulse part (mp) in which a value (b) and a value (c) having a time T in total alternately continue (n-n') times at a duty ratio of (y) and a pulse part (op) of a time width (z) and a value (d). The time width (x), the duty ratio (y) and the time width (z) are values satisfying 0.5T≤(x)≤2T, 0.4≤(y)≤0.6 and 0.5T≤(z)≤1T, respectively, n' is a positive integer of n'≤n, and (a and c)>e>(b and d) is satisfied. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an information recording / reproducing method, an information recording / reproducing apparatus, and an information recording medium which can record and reproduce information on an information recording medium such as a compact disc and can be rewritten.

As one of information recording media capable of recording, reproducing and erasing information by irradiation of electromagnetic waves, particularly laser beams, so-called phase change type information recording media utilizing transition between crystal-amorphous phase or crystal-crystal phase Is well known. In particular, optical memory can be overwritten by a single beam, which is difficult, and the optical system of a drive device that records, reproduces and erases information in the optical memory is simpler. It has become.

  On the other hand, with the rapid spread of CDs (compact discs) in recent years, write-once type compact discs (CD-R) capable of writing information only once have been developed and have begun to spread in the market. However, in the CD-R, if it fails even once when writing information, it cannot be corrected and cannot be used, and must be discarded. Therefore, the practical application of a rewritable compact disc that can compensate for this drawback has been awaited.

  An example of a rewritable compact disc that has been researched and developed is a rewritable compact disc that uses a magneto-optical disc. This compact disc is difficult to overwrite and is compatible with CD-ROM and CD-R. Development of practical application of phase change optical discs, which are advantageous in principle for ensuring compatibility, has been activated.

  Examples of research presentations on rewritable compact discs using phase change optical discs include Furuya (others): Proceedings of the 4th Phase Change Recording Society Symposium, 70 (1992), Kanno (others): 4th Proceedings of the Symposium of Phase Change Recording Society, 76 (1992), Kawanishi (etc.): Proceedings of the 4th Symposium of Phase Change Recording Society, 82 (1992), T. Handa (et al): Jpn. J. et al. Appl. Phys. 32 (1993) 5226, Yoneda (others): Proceedings of the 5th Phase Change Recording Study Group Symposium, 9 (1993), Tominaga (Others): Proceedings of the 5th Phase Change Recording Study Group Symposium, 5 (1993) ) Etc.

None of these are fully satisfactory in overall performance such as ensuring compatibility with CD-R, recording erasure performance, recording sensitivity, number of rewrites, number of reproductions, storage stability, etc. This was mainly due to the low erasure ratio due to the composition and structure of the recording material.
Under these circumstances, there has been a demand for the development of a phase change recording material that has a high erasure ratio and is suitable for high-sensitivity recording and erasing, and a high-performance and rewritable phase change compact disc system.

  The inventors of the present invention have found and disclosed an AgInSbTe-based recording material as a new material for solving the above drawbacks. Representative examples thereof include Patent Document 1, Patent Document 2, and H.264. Iwasaki (et al): pn. J. et al. Appl. Phys. 31 (1992) 461, Ide (others): Proceedings of the 3rd Symposium on Phase Change Recording Research, 102 (1991), H.C. Iwasaki (et al): pn. J. et al. Appl. Phys. 32 (1993) 5241 and the like.

  Although it is apparent that a phase change optical disc having extremely excellent performance can be obtained by these disclosed technologies, these disclosed technologies completely satisfy the above comprehensive performance such as ensuring compatibility with a CD-R, Further improvements are needed to obtain a phase change optical disc system sufficient to form a new market. In particular, when performing PWM (Pulse Width Modulation) recording of EFM (Eight-to-Fourteen Modulation) used in compact discs, a technique for stably and repeatedly recording long marks with less distortion is used as a recording signal quality. It is indispensable to improve the stability and stability during repeated overwriting.

  Various recording compensation methods have been disclosed as methods for improving the quality of recording signals in phase change recording. For example, in Patent Document 3, a method of recording a long amorphous mark using a pulse train is effective in PWM recording when a recording film having a high crystallization speed is used. Further, in the devices described in Patent Document 4 and Patent Document 5, jitter is improved by suppressing the position fluctuation of the edge portion of the mark by increasing the laser energy at the head and tail of the pulse train or increasing the irradiation time. ing.

  Conventionally, as described in Patent Document 6, in an optical disk recording apparatus, scanning is performed while irradiating a light spot such as a laser beam on the optical disk, and the light spot such as a laser beam is modulated with an information signal. A method for recording an information signal on an optical disc is known, and recording (optical) power and recording are performed by reproducing the information signal recorded on the optical disc and monitoring the amplitude of the reproduced signal and the length of the recording mark. A method for optimally adjusting and setting recording conditions such as the width of an optical pulse is also known.

JP-A-7-78031 Japanese Patent Application No. 4-123551 Japanese Unexamined Patent Publication No. 63-266632 JP-A 63-266633 US Pat. No. 5,150,351 Japanese Patent Publication No. 63-29336

  With any of the above-described techniques, it is impossible to obtain one that satisfies the improvement in recording signal quality and the stability at the time of overwriting repeatedly.

  In the above method, it is practically difficult to always set optimum conditions for the following reasons even when an information signal is actually recorded on an optical disk using a mass-produced optical disk recording apparatus.

  That is, as the above method, the recording signal amplitude (difference between the signal level from the unrecorded portion and the signal level from the recording portion) value, which is a typical reproduction signal on the optical disc, is monitored to record each optical disc. There is a method of setting the optimum recording power for the device. The amplitude value of the recording signal is not only the recording power, but also the numerical aperture of the optical pickup, the rim intensity (the intensity of the laser light incident on the condenser lens). Distribution), the size and shape of the light spot, and contamination due to contamination of the optical system over time, and an offset of about 20% to 40% usually occurs between individual optical pickups. The setting value of the optimum recording power is greatly shifted due to the influence. For this reason, it has been extremely difficult to set an optimum recording power with a practically sufficient accuracy (about ± 5%) for an optical disk recording apparatus designed on the assumption of mass production.

Further, there is a variation such that the level of the recording signal does not become the same even with the same recording power among the individual optical disk recording apparatuses, and it is necessary to finely adjust the recording power for each optical disk recording apparatus.
The present invention provides an information recording / reproducing method and information capable of achieving improvement in recording signal quality and stability during repeated overwrite, achieving improvement in reliability and versatility, and setting an optimum recording power An object is to provide a recording / reproducing apparatus and an information recording medium.

In order to achieve the above object, the invention according to claim 1 is directed to recording and reproducing information on the information recording medium by irradiating the information recording medium with electromagnetic waves to cause a phase change in the recording layer of the information recording medium. In the information recording / reproducing method that can be performed and rewritten, when the information is recorded by modulating the signal and performing PWM recording on the information recording medium, the modulated signal width is nT (T is the clock time). ) Is a continuous wave of power level e when a zero signal is recorded or rewritten, and a recording wave pulse train when a modulated signal width of nT is recorded or rewritten is a time width. A duty ratio y is alternately generated between a pulse part fp having x and a power level a, a low level pulse having a total time width of T, and a high level pulse having a power level c. An electromagnetic pulse train comprising a multi-pulse part mp that continues for a total of (n−n ′) times and a pulse part op having a time width z and a power level d, and any one or two of x, y, z is set to 0. 5T ≦ x ≦ 2T, 0.4 ≦ y ≦ 0.6, and 0.5T ≦ z ≦ 1T, n ′ is a positive integer of n ′ ≦ n, and (a and c)>e> (B and d).

According to the second aspect of the present invention, the information recording medium is irradiated with electromagnetic waves to cause a phase change in the recording layer of the information recording medium, information can be recorded on and reproduced from the information recording medium, and rewriting is possible. In the information recording / reproducing method, when recording information by modulating a signal and performing PWM recording on the information recording medium, recording of a zero signal whose modulated signal width is nT (T is a clock time) Alternatively, the recording wave at the time of rewriting is a continuous electromagnetic wave of power level e, and the recording wave pulse train at the time of recording or rewriting one signal whose modulated signal width is nT has a time width x and a power level a. An electromagnetic wave pulse train composed of a pulse part fp, a pulse part op having a time width z and a power level d, x and z are set to 0.5T ≦ x ≦ 2T, 0.5T ≦ z ≦ 1T, and a>e> d To.

In the invention according to claim 3, the information recording medium is irradiated with electromagnetic waves to cause a phase change in the recording layer of the information recording medium, information can be recorded on and reproduced from the information recording medium, and rewriting is possible. The information recording / reproducing apparatus comprises: a recording unit that modulates a signal and records information on the information recording medium by a PWM recording method; and a recording control unit that controls the recording unit. A recording wave at the time of recording or rewriting a zero signal whose signal width after modulation is nT (T is a clock time) is a continuous electromagnetic wave of power level e, and recording of one signal whose signal width after modulation is nT or The recording wave pulse train when rewriting is performed, the pulse part fp having the time width x and the power level a, the low level pulse and the power level of the power level b having the total time width of T And an electromagnetic wave pulse train comprising a multi-pulse part mp in which a high-level pulse is alternately repeated (n−n ′) times with a duty ratio y and a pulse part op having a time width z and a power level d, and x, y, Any one or two of z are variable in the range of 0.5T ≦ x ≦ 2T, 0.4 ≦ y ≦ 0.6, 0.5T ≦ z ≦ 1T, and n ′ is a positive value of n ′ ≦ n. And (a and c)>e> (b and d).

In the invention according to claim 4, the information recording medium is irradiated with electromagnetic waves to cause a phase change in the recording layer of the information recording medium, information can be recorded on and reproduced from the information recording medium, and rewriting is possible. The information recording / reproducing apparatus comprises: a recording unit that modulates a signal and records information on the information recording medium by a PWM recording method; and a recording control unit that controls the recording unit. A recording wave at the time of recording or rewriting a zero signal whose signal width after modulation is nT (T is a clock time) is a continuous electromagnetic wave of power level e, and recording of one signal whose signal width after modulation is nT or A recording wave pulse train when rewriting is performed, an electromagnetic wave pulse train comprising a pulse part fp having a time width x and a power level a, and a pulse part op having a time width z and a power level d. And x, y, either one or two z 0.5T ≦ x ≦ 2T, and 0.5T ≦ z ≦ 1T, it is an a>e> d.

According to the present invention, it is possible to stably record and rewrite a high-quality signal in a method of recording information on a phase change information recording medium by a PWM recording method.

Figure 1 shows schematically an example of a 3 T signal to a pulse waveform of a recording wave in the first embodiment of a phase-change information recording and reproducing apparatus according to the present invention. In this embodiment, as shown in FIG. 14, a phase change type information recording medium 11 made of a phase change type optical disk is rotationally driven by a drive means 12 made of a spindle motor, and a recording / reproducing pickup 13 is a laser as a light source drive means. A phase change occurs in the recording layer of the information recording medium by driving a light source composed of a semiconductor laser by the driving circuit 14 and irradiating the information recording medium 11 with laser light as an electromagnetic wave from the semiconductor laser via an optical system (not shown). Then, the reflected light from the information recording medium 11 is received by the recording / reproducing pickup 13 to record and reproduce information on the information recording medium 11. The optimum recording power of the recording / reproducing pickup 13 is set by a recording power setting circuit 15 as recording power setting means.

  As described above, in the present embodiment, the phase change information recording medium 11 is irradiated with laser light as an electromagnetic wave by the recording / reproducing pickup 13 to cause a phase change in the recording layer of the information recording medium 11. 11 is a phase change type information recording / reproducing apparatus that records and reproduces information to and from which information can be rewritten. The signal to be recorded is modulated by a modulation unit and recorded on an information recording medium by a recording / reproducing pickup 13. Thus, a recording means for recording information is provided. The recording means including the pickup 13 records information by a so-called PWM recording method in which the mark is recorded so as to record a signal as the mark width on the recording layer of the information recording medium. The recording means modulates a signal to be recorded using an EFM (Eight-to-Fourteen Modulation) modulation system suitable for information recording on a rewritable compact disk, or an improved modulation system thereof, using a clock in a modulation unit.

  When the PWM recording is performed, the recording unit records a zero signal whose modulated signal width is nT (n is a predetermined value, T is a clock time: a time corresponding to a clock period used for signal modulation) or The recording light at the time of rewriting is continuous light of power level e, and the pulse train of the recording light at the time of recording or rewriting one signal whose modulated signal width is nT has a time width x and a power level a. A multi-pulse part mp in which a pulse part fp, a low-level pulse of power level b having a total time width of T and a high-level pulse of power level c are alternately (n−n ′) times with a duty ratio y And an electromagnetic pulse train composed of a pulse part op having a time width z and a power level d, and x, y, z are 0.5T ≦ x ≦ 2T, 0.4 ≦ y ≦ 0.6, and 0.5T ≦ z ≦. 1T, n is a positive integer greater than or equal to 1 And then, 'a n' n is a positive integer of ≦ n, and (a and c)> e> (b and d). 1B shows a case where n ′ = 1, FIG. 1C shows a case where n ′ = 2, and FIG. 1C shows a case where n ′ = 3.

  In general, recording of one signal ('1' portion of a binary signal) on a phase change information recording medium is performed by forming an amorphous portion (amorphous phase) in the recording layer of the phase change information recording medium. In order to form an amorphous phase in the recording layer of the phase change information recording medium, it is necessary to raise the temperature to the melting point of the recording layer or higher and then cool down sufficiently. Here, the pulse part fp raises the temperature of the recording layer of the phase change information recording medium above the melting point to form the top part of the recording mark, and the multi-pulse part mp raises the temperature of the recording layer to raise the intermediate part of the recording mark. The pulse part op cools the recording layer to form the trailing end of the recording mark. If the linear velocity of the phase change information recording medium is varied, the amount of electromagnetic radiation applied to the phase change information recording medium changes, and the temperature rises above the melting point of the recording layer and the subsequent cooling rate changes. It is effective to appropriately set the temperature rise to the melting point of the recording layer and the subsequent cooling rate by changing the linear velocity of the type information recording medium.

  On the other hand, when information is recorded on the recording layer of the phase change information recording medium by the PWM recording method, information is provided at the edge portion of the recording mark, so that the boundary between the recording portion and the unrecorded portion on the recording layer. In order to avoid ambiguity and erasing of the recorded portion due to crystallization, it is necessary to suppress the influence of heat on the portion other than the portion to be recorded in the recording layer.

  As described above, in order to clearly distinguish the temperature raising condition between the portion to be recorded on the recording layer and the portion to be kept at room temperature, it is necessary to prevent generation of excessive heat in the recording layer, and heat in the film of the recording layer. It is effective to keep the conduction of the material low. By doing so, the boundary between the recorded portion and the unrecorded portion is clarified, and a recording signal having a good quality with a small jitter can be obtained.

  The use of the recording waveform shown in FIG. 1 by the recording means makes it possible to obtain optimum recording conditions that satisfy these conditions, and the quality is good when performing PWM recording on the recording layer of the phase change information recording medium. Recording marks can be recorded and rewritten stably. Here, preferable recording conditions are such that x, y, z are 0.5T ≦ x ≦ 2T, 0.4 ≦ y ≦ 0.6, 0.5T ≦ z ≦ 1T, and (a and c)> e> (B and d).

Thus, this embodiment causes a phase change in the recording layer of the information recording medium by irradiating an electromagnetic wave to the information recording medium, the recording of information to the information recording medium performs reproduction, and, rewrite In the information recording / reproducing method, the signal width after modulation is nT (T is a clock time) when the information is recorded by modulating the signal and performing PWM recording on the information recording medium. The recording wave at the time of recording or rewriting is a continuous electromagnetic wave of power level e, and the recording wave pulse train at the time of recording or rewriting one signal whose modulated signal width is nT is represented by time width x and power level a. And a low level pulse of power level b and a high level pulse of power level c having a total time duration of T are alternately (n−n ′) times with a duty ratio y. An electromagnetic wave pulse train consisting of a multi-pulse part mp that continues and a pulse part op having a time width z and a power level d, and x, y, z are 0.5T ≦ x ≦ 2T, 0.4 ≦ y ≦ 0.6, Since 0.5T ≦ z ≦ 1T, n ′ is a positive integer of n ′ ≦ n, and (a and c)>e> (b and d), the phase-change type information recording medium is used in the PWM recording method. In the method of recording information, a signal having a good quality can be stably recorded and rewritten.

This embodiment also causes a phase change in the recording layer of the information recording medium by irradiating an electromagnetic wave to the information recording medium, the recording of information to the information recording medium performs reproduction, and, rewritable The information recording / reproducing apparatus includes recording means for modulating a signal and recording information on the information recording medium by a PWM recording method. The recording means has a modulated signal width of nT (T is a clock time). A recording wave at the time of recording or rewriting 0 signal is a continuous electromagnetic wave of power level e, and a recording wave pulse train at the time of recording or rewriting 1 signal whose modulated signal width is nT is a time width x And a pulse part fp having a power level a, a low level pulse of a power level b having a total time width of T, and a high level pulse of a power level c alternately with a duty ratio y An electromagnetic wave pulse train composed of a multi-pulse part mp that is continuous (n−n ′) times and a pulse part op having a time width z and a power level d, and x, y, z are 0.5T ≦ x ≦ 2T, 0.4 ≦ y ≦ 0.6, 0.5T ≦ z ≦ 1T, n ′ is a positive integer n ′ ≦ n, and (a and c)>e> (b and d) It is possible to stably record and rewrite a high-quality signal in an apparatus that records information on a recording medium by a PWM recording method.

In the first modification of this embodiment , in the information recording / reproducing method, the EFM modulation method or its improved modulation method is used as the method for modulating the signal to be recorded, and n ′ = 2. A recording method suitable for a disc can be provided.

Further, in the second modification of this embodiment , in the information recording / reproducing apparatus, the recording means modulates the signal to be recorded by the EFM modulation method or its improved modulation method and sets n ′ = 2. A recording device suitable for a compact disc can be provided.

In the above embodiment, x, y, and z are preferably determined by the reflected light intensity of the phase change information recording medium in order to obtain more suitable recording conditions. In the third modification of the embodiment of the information recording / reproducing apparatus, in the above embodiment, x, y, z and the power of the reproducing light for reproducing the signal according to the reflected light intensity at the time of reproducing the information recording medium. Means for determining the level are provided, and an optimum recording pulse waveform can be obtained.

Thus, in the third modification of this embodiment, in the information recording and reproducing method, the reflected wave intensity of reproducing the information recording medium, x, y, z and a power of an electromagnetic wave for regenerating a signal Since the level is determined, an optimum recording pulse waveform can be obtained in the method of recording information on the phase change type information recording medium by the PWM recording method.

Further, in the third modification of this embodiment, in the information recording and reproducing apparatus, the reflected wave intensity of reproducing the information recording medium, x, y, and z, and electromagnetic wave power level to reproduce the signal Therefore, an optimum recording pulse waveform can be obtained in the method of recording information on the phase change information recording medium by the PWM recording method.

In a second embodiment of a phase-change information recording and reproducing apparatus according to the present invention, in the first embodiment, a recording unit for recording information by PWM recording system modulates a signal to the information recording medium, Recording control means for controlling the recording means, and the recording means records information by modulating the signal by the modulation section and recording it on the information recording medium by the recording / reproducing pickup 13.

  The recording means modulates the signal and records information on the information recording medium by the PWM recording method. The recording means outputs the recording wave when the zero signal having a predetermined signal width is recorded or rewritten after the modulation with the first power. A recording wave pulse train when recording or rewriting one signal having a predetermined signal width nT after modulation with a continuous electromagnetic wave of level e is represented by a pulse part fp having a first time width x and a second power level a. , A low level pulse of the third power level b and a c high level pulse of the fourth power level having a time width T of the clock time in total, alternately with a predetermined duty ratio y for a predetermined number of times (n−n ′). Let it be an electromagnetic wave pulse train comprising a continuous multi-pulse part mp and a pulse part op having a second time width z and a fifth power level d. The recording control unit controls the recording unit to set each of the time width x, the duty ratio y, and the time width z according to the linear velocity of the information recording medium.

Thus, the second embodiment, phase change occurs in the recording layer of the information recording medium by irradiating an electromagnetic wave to the information recording medium, the recording of information to the information recording medium, performs reproduction, In addition, in the information recording / reproducing method capable of rewriting, when a signal is modulated and information is recorded on the information recording medium by a PWM recording method, a signal having a predetermined signal width is recorded or rewritten after the modulation. The recording wave pulse train when the recording wave at the time is a continuous electromagnetic wave of the first power level e and one signal having a predetermined signal width nT is recorded or rewritten after modulation is represented by the first time width x and the second The pulse part fp having the power level a, the low level pulse of the third power level b and the high level pulse of the fourth power level c having the total time width T of the clock time are alternately arranged. An electromagnetic wave pulse train comprising a multi-pulse part mp that continues a predetermined number of times (n−n ′) with a predetermined duty ratio y, and a pulse part op having a second time width z and a fifth power level d, Since the time width x, the duty ratio y, and the second time width z are set according to the linear velocity, a signal of good quality in the method of recording information on the phase change information recording medium by the PWM recording method. Can be recorded and rewritten stably.

Further, the second embodiment, phase change occurs in the recording layer of the information recording medium by irradiating an electromagnetic wave to the information recording medium, the recording of information to the information recording medium performs reproduction, and, A rewritable information recording / reproducing apparatus includes a recording unit that modulates a signal and records information on an information recording medium by a PWM recording method, and a recording control unit that controls the recording unit, and modulates the signal. When recording information on the information recording medium by the PWM recording method, the recording wave when recording or rewriting a zero signal having a predetermined signal width after modulation is made a continuous electromagnetic wave of the first power level e, and modulated. A recording wave pulse train when one signal having a predetermined signal width nT is recorded or rewritten later is combined with a pulse part fp having a first time width x and a second power level a in total. A multi-level signal in which a low-level pulse of the third power level b and a high-level pulse of the fourth power level c having a time width T of the clock time are alternately repeated a predetermined number of times (n−N ′) with a predetermined duty ratio y. An electromagnetic wave pulse train comprising a pulse part mp and a pulse part op having a second time width a and a fifth power level d, and the recording control means includes the first time width x, the duty ratio y, the first Since each of the two time widths z is set in accordance with the linear velocity, a high-quality signal can be stably recorded and rewritten in an apparatus for recording information on the phase change information recording medium by the PWM recording method.

The first to third modifications can be applied to the second embodiment in the same manner as when applied to the first embodiment.

  A recordable compact disc (CD-R) generally records and reproduces information using a pickup having a wavelength of about 780 nm and NA of 0.5, and the reflected light intensity of the phase change type information recording medium is reduced using this pickup. The lower the conversion value when converted to reflectance, the smaller the value of x is, and the higher the conversion value, the larger x. Specifically, the value of x is 0.5T to 1T when the reflectance of the information recording medium is approximately 10 to 15%, and 0.75T or more when the reflectance of the information recording medium is approximately 15 to 20%. If the reflectance of the information recording medium is about 1.25T and about 20 to 25%, 1T to 1.5T is more preferable, and if the reflectance of the information recording medium is about 25 to 30%, 1.25T to 2T is more preferable. . The CD-R calibration disk provided by Philips Consumer Electronics was used for calibration of the reflectance of the information recording medium here, but actually recording and reproducing information on the phase change type information recording medium, In the rewritable drive system, it is not necessary to convert the reflected light intensity of the phase change information recording medium into the reflectance, and x can be controlled only by the reflected light intensity of the phase change information recording medium. is there.

  FIG. 2 shows the relationship between b and C1 error (CD standard error) when b = d. It can be seen that b has an appropriate value depending on the error rate of the C1 error. If b is too large, the rapid cooling condition of the information recording medium is lost, and a stable amorphous mark cannot be recorded on the information recording medium. On the other hand, if b is too small, it is difficult to raise the temperature, so that it becomes difficult to record an amorphous mark on the information recording medium with the same a, c, or e, which hinders sensitivity. Accordingly, the appropriate values of b and d depend on the linear velocity of the information recording medium at the time of recording, the usage environment of the information recording medium, the rapid cooling / heating structure of the information recording medium, the variation in the shaping of the beam irradiated to the information recording medium of the pickup, etc. However, it is effective to adjust the values of b and d in order to correct these variations and obtain a more reliable recording condition.

In a third embodiment of the information recording / reproducing apparatus to which the present invention is applied, in the fourth embodiment to be described later, there is provided means for detecting a C1 error and substantially determining b and d by the C1 error. Highly reliable signal recording can be performed.

As described above, in the information recording / reproducing method of the fourth embodiment , since the error is detected and b and d are substantially determined by the error, the third embodiment provides a highly reliable signal recording method. it can.
In the third embodiment, since the information recording / reproducing apparatus of the fourth embodiment includes means for detecting an error and substantially determining b and d based on the error, a highly reliable signal recording apparatus. Can provide.

Further, in the fourth embodiment of the information recording / reproducing apparatus to which the present invention is applied, in the above embodiment, the detecting means for detecting the signal from the information recording medium at the time of reproducing information from the information recording medium, and the detecting means DC coupling means for DC coupling the detected signal, and high level I1 and low level I2 at the output level of the DC coupling means m = (I1-I2) / I1 × 100 (1)
And means for substantially determining a and / or c from this m.

  FIG. 3 shows the relationship between m represented by Equation (1) and a and e when a = c. It can be seen that m mainly depends only on a and hardly depends on e. From this figure, it can be seen that a and b having sufficient signal amplitude can be selected by detecting m, an optimum recording power with few errors can be obtained, and a highly reliable system can be secured. The appropriate value of m depends on the system configuration, but m ≧ 0.5 is appropriate for improving the reliability such as error rate.

As described above, in the fourth embodiment, in the information recording / reproducing method of the first and second embodiments, the signal detected by the detecting means from the information recording medium at the time of reproducing information from the information recording medium is DC coupled. Since m = (I1−I2) / I1 × 100 is calculated from the high level I1 and the low level I2 at the output level of the DC coupling, and a and / or c are substantially determined by this m, The optimum recording power can be obtained in the method of recording information on the variable information recording medium by the PWM recording method.

In the fourth embodiment, in the information recording / reproducing apparatus of the first and second embodiments, a detecting means for detecting a signal from the information recording medium at the time of reproducing information from the information recording medium, and this detecting means DC coupling means for DC coupling the detected signal, and m = (I1−I2) / I1 × 100 are calculated from the high level I1 and the low level I2 at the output level of the DC coupling means. And a means for determining a and / or c, it is possible to obtain an optimum recording power in an apparatus for recording information on a phase change information recording medium by a PWM recording method.

In the fifth embodiment of the information recording / reproducing apparatus to which the present invention is applied, in the first to fourth embodiments, the detecting means for detecting a signal from the information recording medium during reproduction of reproducing information from the information recording medium. AC coupling means for AC coupling the signal detected by the detection means, and from the high level S1 and the low level S2 at the output level of this AC coupling β = (S1 + S2) / (S1-S2) × 100 · (2)
And means for substantially determining e and / or a, c from this β.

  FIG. 4 shows the relationship between β expressed by equation (2) and a and e when a = c. It can be seen that β is dependent on both a and e. Also, in FIG. 4, the numbers indicate the stability that can be overwritten repeatedly while maintaining low jitter, and the larger the number, the greater the number of possible overwrites. From this figure, it can be seen that by detecting β, it is possible to determine substantial values of a, c, and e that can ensure the optimum overwrite performance with the optimum recording power and the reliability of the system.

  The range of β is preferably from −2 to 10, but more preferably from 0 to 8, and most preferably from 2 to 7. The relationship between β and e is similar to the relationship between emetry calculated from the amplitudes of the 3T signal and the 11T signal and e. Therefore, it is possible to substitute β with asymmetry. However, it is desirable to use β because the detection of the amplitude of the 11T signal is easier than the detection of the amplitude of the 3T signal in terms of the system configuration.

  In addition, β has a tendency that the dependence on a is insensitive to information recording media, but is always strong against e. From this, it is possible to ensure optimum overwrite performance and system reliability by substantially determining a and / or c based on the value of m and then determining e based on the value of β. It is considered suitable. Further, in the actual system, even when other parameters such as e / a and e / c are used when controlling the parameters a to e, there is no problem.

As described above, in the fifth embodiment , in the information recording / reproducing methods of the first to fourth embodiments , the signal detected by the detecting means from the information recording medium at the time of reproducing information from the information recording medium is AC coupled. Then, β = (S1 + S2) / (S1−S2) × 100 is calculated from the high level S1 and the low level S2 at the output level of the AC coupling, and e and / or a and c are substantially determined by this β. Therefore, the optimum recording power can be obtained in the method of recording information on the phase change information recording medium by the PWM recording method.

In the first to fourth embodiments , in the information recording / reproducing apparatus of the first and second embodiments , detection means for detecting a signal from the information recording medium at the time of reproducing information from the information recording medium, AC coupling means for AC coupling the signal detected by the detection means, and β = (S1 + S2) / (S1-S2) × 100 from the high level S1 and the low level S2 at the output level of this AC coupling, Means for substantially determining e and / or a, c by this β, so that an optimum recording power can be obtained in an apparatus for recording information on a phase change information recording medium by the PWM recording method.

In the fifth embodiment, in the information recording and reproducing method, since β performs recording and / or rewriting of the signal to control the power level of an electromagnetic wave so it is -2 to 10, trust overwriting Highly optimal recording power can be obtained.

In the fifth embodiment, in the information recording and reproducing apparatus, since comprising means for β is perform recording and / or rewriting of the signal to control the power level of an electromagnetic wave so is -2 to 10 It is possible to obtain optimum recording power with high reliability at the time of overwriting.

In the sixth embodiment of the information recording / reproducing apparatus to which the present invention is applied, in the above embodiment, the power level of the electromagnetic wave is controlled so that e / a or e / c is 0.3 or more and 0.7 or less. A means for performing signal recording and / or rewriting is provided, and an optimum recording power can be obtained as in the first to fifth embodiments.

Thus, in the sixth embodiment, in the information recording / reproducing method of the first and second embodiments, the power level of the electromagnetic wave so that e / a or e / c is 0.3 or more and 0.7 or less. Since the signal is recorded and / or rewritten by controlling the signal, optimum recording power can be obtained in the method of recording information on the phase change information recording medium by the PWM recording method.

In the sixth embodiment, the power level of the electromagnetic wave is controlled so that e / a or e / c is not less than 0.3 and not more than 0.7 in the information recording / reproducing apparatus of the first and second embodiments. Since the signal recording and / or rewriting means is provided, an optimum recording power can be obtained in an apparatus for recording information on the phase change information recording medium by the PWM recording method.

In the seventh embodiment of the information recording / reproducing apparatus to which the present invention is applied, in the above embodiment, 1.2 to 1.4 m / s or more of the CD reference linear velocity (CD 1 × speed), 4.8 to 5.6 m / s. The information recording medium is rotated by the rotation driving means at a rotation speed equal to or less than s (CD 4 times speed). By setting the rotational linear velocity of the information recording medium to this linear velocity region, compatibility with an existing CD system (system for recording and reproducing information on a CD) can be achieved. In recent years, especially in the area of CD-ROM players, a CD-ROM whose rotational linear velocity is set to a high linear velocity of twice or more is used. On the other hand, in the field of music and video (Video-CD), real-time Since playback is basic, a CD of 1 × speed is mainly used.

Thus, in the seventh embodiment , in the information recording / reproducing apparatus of the first and second embodiments , the information recording medium is rotated at a linear velocity of 1.2 m / s to 5.6 m / s during information recording. Since it is rotated, recording conditions suitable for a rewritable compact disc can be obtained.

Further, in the seventh embodiment, first, the information recording and reproducing method or the first of the second embodiment, an information recording medium used in the information recording and reproducing apparatus of the second embodiment, when the information recording 1 Since it is rotated at a rotational linear velocity of not less than 2 m / s and not more than 5.6 m / s, an information recording medium suitable for a rewritable compact disc can be provided.

  A rewritable CD system is used as a multimedia that does not select information to be recorded, and records, reproduces, and rewrites information on various types of CDs. When recording, reproducing and rewriting information on the CD, it is inevitable to use a combination of a reproduction system and a recording system having different linear speeds, in order to eliminate the difference between the reproduction time and the time required for information recording. The storage means is indispensable.

In an eighth embodiment of the information recording / reproducing apparatus to which the present invention is applied, in the above first to seventh embodiments, the storage means is mainly composed of a semiconductor memory, and while reproducing a music CD in real time, When information is recorded by a CD double speed system having a storage means, a part of the information to be recorded can be stored in the storage means, and the difference between the reproduction time and the time required for information recording can be eliminated.

Thus, in the eighth embodiment, the seventh information recording / reproducing apparatus includes means for temporarily storing a part of information to be recorded, so that the phase change type information recording medium can be rewritten and compact. The versatility and compatibility of the information recording medium used in the system used for the disc can be improved, and at the same time, the reliability of the system can be improved.

  In addition, when real-time playback is not necessary, such as when editing a moving image, it is required that the time required for information recording be short, and at the same time, a system configuration that requires real-time playback at 1 × CD speed with the same device is also fully considered. In this case, a system having means capable of making the rotational speed of the information recording medium during information recording higher than the rotational linear speed of the information recording medium during information reproduction is desired.

Therefore, in the ninth embodiment of the information recording / reproducing apparatus to which the present invention is applied, in the first to eighth embodiments, the rotational linear velocity of the information recording medium at the time of information recording is the same as that of the information recording medium at the time of information reproduction. It is provided with a means capable of making it higher than the rotational linear velocity, and the versatility and compatibility of the system using the rewritable compact disc can be enhanced.

Thus, in the ninth embodiment, in the information recording / reproducing apparatus of the eighth embodiment, the rotational linear velocity of the information recording medium during information recording is set higher than the rotational linear velocity of the information recording medium during information reproduction. Therefore, the versatility and compatibility of the system used for the rewritable compact disc can be improved.

FIG. 5 shows an embodiment of the information recording medium. This information recording medium is used in the above-described embodiment, and has a heat-resistant protective layer 2, a recording layer 3, a heat-resistant protective layer 4, and a reflective heat radiation layer 5 provided on a substrate 1 in order. The heat-resistant protective layers 2 and 4 are not necessarily provided on both sides of the recording layer 3, but when the substrate 1 is made of a material having low heat resistance such as polycarbonate resin, the heat-resistant protective layer 2 is provided. It is desirable.

  The recording layer 3 is mainly composed of Ag, In, Sb, and Te, and various vapor phase growth methods such as a vacuum deposition method, a sputtering method, a plasma CVD method, a photo CVD method, an ion plating method, and an electron beam deposition method. It can be formed by methods. For forming the recording layer 3, a wet process such as a sol-gel method can be applied in addition to the vapor phase growth method. The thickness of the recording layer 3 is 100 to 1000 mm, preferably 150 to 700 mm. If the recording layer 3 is thinner than 100 mm, the light absorption performance is remarkably lowered, and the recording layer 3 does not serve as a recording layer. On the other hand, if the recording layer 3 is thicker than 1000 mm, a uniform phase change is difficult to occur at high speed.

  The material of the substrate 1 is usually glass, ceramics or resin, and the resin substrate is preferable in terms of moldability and cost. Representative examples of the resin include polycarbonate resin, acrylic resin, epoxy resin, polystyrene resin, acrylonitrile styrene copolymer resin, polyethylene resin, polypropylene resin, silicon resin, fluorine resin, ABS resin, urethane resin and the like. However, the material of the substrate 1 is preferably a polycarbonate resin or an acrylic resin in terms of processability and optical characteristics. Further, the shape of the substrate 1 may be a disk shape, a card shape or a sheet shape.

Examples of materials for the heat-resistant protective layers 2 and 4 include metal oxides such as SiO, SiO ₂ , ZnO, SnO ₂ , Al ₂ O ₃ , TiO ₂ , In ₂ O ₃ , MgO, and ZrO ₂ , Si ₃ N ₄ , Nitrides such as AlN, TiN, BN, ZrN, sulfides such as ZnS, In ₂ S ₃ , TaS ₄ , carbides such as SiC, TaC, B ₄ C, WC, TiC, ZrC, diamond carbon or a mixture thereof. Can be mentioned. These materials can be used alone as a protective layer, but they may be mixed with each other. Further, impurities may be included as necessary. However, the melting point of the heat-resistant protective layers 2 and 4 needs to be higher than the melting point of the recording layer 3.

  Such heat-resistant protective layers 2 and 4 can be formed by various vapor phase growth methods such as vacuum vapor deposition, sputtering, plasma CVD, photo CVD, ion plating, and electron beam vapor deposition. The film thickness of the heat-resistant protective layer 2 is 500 to 2500 mm, preferably 1200 to 2300 mm. When the heat-resistant protective layer 2 is thinner than 500 mm, it does not function as a heat-resistant protective layer. On the other hand, when the heat-resistant protective layer 2 is thicker than 2500 mm, the sensitivity is lowered and interface peeling tends to occur. Moreover, the heat-resistant protective layer 2 can be multilayered as needed.

  The film thickness of the heat-resistant protective layer 4 disposed on the upper part of the recording film 3 is 100 to 1500 mm, preferably 150 to 1000 mm. When the heat-resistant protective layer 4 becomes thinner than 100 mm, the heat-resistant protective layer 4 does not function as a heat-resistant protective layer, and conversely when it becomes thicker than 1500 mm, it is in a so-called low linear velocity region of 1.2 to 5.6 m / s. When it is used, the C / N, the erasure ratio is lowered, the jitter is raised, etc., and good characteristics cannot be obtained. Moreover, the heat-resistant protective layer 4 can be multilayered as needed.

  As the reflective heat dissipation layer 5, a metal material such as Al or Au, or an alloy thereof can be used. The reflective heat radiation layer 5 is not necessarily required, but it is desirable to provide it in order to release excessive heat and reduce the heat burden on the information recording medium. Such a reflective heat dissipation layer 5 can be formed by various vapor phase growth methods such as vacuum vapor deposition, sputtering, plasma CVD, photo CVD, ion plating, electron beam vapor deposition and the like. The thickness of the reflective heat radiation layer 5 is 300 to 2000 mm, preferably 500 to 1500 mm.

Thus, this embodiment, first or was the second information recording method of the embodiment or is an information recording medium used in the information recording and reproducing apparatus, at least the substrate, the heat-resistant protective layer, a recording layer Therefore, it is possible to provide an optimum information recording medium for recording information on the phase change information recording medium by the PWM recording method.

In addition, since the first modification of the present embodiment includes the reflective heat dissipation layer, it is possible to provide an information recording medium optimal for recording information on the phase change information recording medium by the PWM recording method.

In the second modification of the present embodiment , since the heat-resistant protective layer is provided on both sides so as to sandwich the recording layer, information is recorded on the phase change information recording medium by the PWM recording method. An optimal information recording medium can be provided.

In the third modification of the present embodiment , the film thickness of the heat-resistant protective layer disposed between the substrate and the recording layer is 500 to 2500 angstroms. An information recording medium optimal for recording information by the PWM recording method can be provided.

In the fourth modification of the present embodiment , when the heat-resistant protective layer is provided on the recording layer, the film thickness of the heat-resistant protective layer is set to 100 to 1500 angstroms. An information recording medium optimum for recording information on the information recording medium by the PWM recording method can be provided.

In the fifth modification of the present embodiment , since the main constituent elements of the recording layer are Ag, In, Sb, and Te, information is recorded on the phase change information recording medium by the PWM recording method. An optimal information recording medium can be provided.

In the sixth modification of the present embodiment , since the recording layer has a thickness of 100 to 1000 angstroms, the information recording medium is most suitable for recording information on the phase change information recording medium by the PWM recording method. Can provide.

In the seventh modification of the present embodiment , since the substrate is made of glass, ceramic, or resin, the information recording is most suitable for recording information on the phase change information recording medium by the PWM recording method. Media can be provided.

Further, in the eighth modification of the present embodiment , the material of the heat-resistant protective layer is SiO, SiO ₂ , ZnO, SnO ₂ , Al ₂ O ₂ , TiO ₂ , In ₂ O ₂ , MgO, ZrO ₂ or the like. Metal oxides, nitrides such as Si ₂ N ₄ , AlN, TiN, BN, ZrN, sulfides such as ZnS, In ₂ S ₃ , TaS ₄ , SiC, TaC, B ₄ C, WC, TiC, ZrC, etc. Therefore, it is possible to provide an optimal information recording medium for recording information on the phase change information recording medium by the PWM recording method.

In the ninth modification of the present embodiment , since the reflective heat radiation layer is made of a metal material such as Al or Au, or an alloy thereof, information is recorded on the phase change information recording medium by the PWM recording method. An information recording medium optimum for recording can be provided.

In the tenth modification of the present embodiment , since the thickness of the reflective heat radiation layer is 300 to 2000 angstroms, the information recording is most suitable for recording information on the phase change information recording medium by the PWM recording method. Media can be provided.

In the above embodiment, various electromagnetic waves such as laser light, electron beam, X-ray, ultraviolet light, visible light, infrared light, and microwave can be adopted as electromagnetic waves used for recording, reproducing and erasing information on the information recording medium. However, a laser beam by a small and compact semiconductor laser is optimal when it is attached to an information recording / reproducing apparatus.
It will be specifically described by the present invention embodiment. However, these embodiments do not limit the present invention.

The first example of the present invention is an example of the information recording / reproducing apparatus of each embodiment , and an information recording medium using an Ag-In-Sb-Te system as a recording layer is rotated at 2.8 m / s by a driving means. Then, an EFM modulation signal having a clock frequency of 8.64 MHz was recorded on the information recording medium by the recording means by the PWM recording method. The pickup constitutes a part of a recording means, a reproducing means and an erasing means. The emission wavelength of the semiconductor laser used for the pickup is 780 nm, and the NA of the objective lens used for the pickup is 0.5. The information recording medium has a heat resistant protective layer composed of a 180 nm thick ZnS / SiO2 layer, a 18 nm thick Ag—In—Sb—Te recording layer, a 25 nm thick recording layer on a 1.2 nm thick polycarbonate resin substrate. A heat-resistant protective layer made of a ZnS / SiO2 layer, a reflective heat radiation layer made of an Al alloy having a thickness of 100 nm, and a UV coating layer are provided.

  FIG. 6 shows the influence of jitter on the power margin after 1000 overwrites of x shown in FIGS. The parameters of the recording waveform were y = 0.5, z = 0.65T, b = 1 mW (Pr), d = 1 mW, e = 6 mW (Pe), and n ′ = 2. From this figure, it can be seen that by properly selecting x, a condition capable of widening the margin can be obtained, and a highly reliable system capable of stable overwriting can be obtained. In FIG. 7, Pw is Pw = a = c.

The second example of the present invention is an example of the information recording / reproducing apparatus of each embodiment , and FIG. 8 shows the reflectance calculated from the reflected light intensity of the information recording medium and the preferred value of x in the second example . Show the relationship. For the calibration of the reflectance, a CD-R calibration disk provided by Philips Consumer Electronics was used.

In the second embodiment, the information recording medium is of the similar to those used in the first embodiment, the shape of the film thickness and the groove of the substrate of each layer is different from that used in the first embodiment Thus, an information recording medium having a reflectance different from that used in the first example was produced. Pickup for information recording on the information recording medium, the recording speed as in the first embodiment has a condition suitable for each information recording medium.

  A suitable value of x in FIG. 8 is x when jitter is the best, and other parameters are also suitable for each information recording medium. From this figure, there is a strong relationship between the reflectance of the information recording medium and a suitable x, and if the reflectance of the information recording medium is about 10 to 15%, 0.5T to 1T, the reflection of the information recording medium If the rate is about 15 to 20%, 0.75T to 1.25T, if the reflectance of the information recording medium is about 20 to 25%, 1T to 1.5T, and the reflectance of the information recording medium is about 25 to 30. % Indicates that 1.25T to 2T is more preferable. Thus, the optimum value of x can be determined by detecting the reflectance of the information recording medium used.

The third example of the present invention is an example of the information recording / reproducing apparatus of each embodiment , and FIG. 9 shows the relationship between y and jitter when the same information recording medium as in the first example is used in the third embodiment. Show. In the third embodiment, the pickup and recording speed were the same as in the first embodiment. The parameters of the recording waveform were x = 1T, z = 0.75T, a = 12 mW, b = 1 mW (Pr), c = 12 mW, d = 1 mW, e = 6 mW, and n ′ = 2. From this figure, it can be seen that by properly selecting y, conditions for suppressing jitter can be obtained, and a highly reliable system can be obtained.

The fourth example of the present invention is an example of the information recording / reproducing apparatus of each embodiment , and FIG. 10 shows the relationship between z and jitter in the fourth example . In the fourth embodiment, using the same information recording medium and the first embodiment, the pickup and recording speed was the same as the first embodiment. The parameters of the recording waveform are x = 1.2T (see FIG. 11), y = 0.5, a = 12 mW, b = 1 mW (Pr), c = 12 mW, d = 1 mW, e = 6 mW, n ′. = 2. From this figure, it can be seen that by selecting z appropriately, conditions for suppressing jitter can be obtained, and a highly reliable system can be obtained.

The fifth example of the present invention is an example of the information recording / reproducing apparatus according to each embodiment . In this fifth example , when the same information recording medium as that of the first example is used, the stability of repeated overwriting and β, The relationship of a is shown in FIG. In FIG. 4, the numerals indicate power multipliers of the number of times of repeated overwriting. That is, 3 indicates that the number of times of repeated overwriting is 1000 or more, 2 indicates that the number of times of repeated overwriting is 100 or more and less than 1000 times, and 1 indicates that the number of times of repeated overwriting is 100 or less. Indicates that As is clear from this figure, stable repeated overwriting performance is obtained when β is −2 or more and 10 or less.

The sixth example of the present invention is an example of the information recording / reproducing apparatus of each embodiment , and shows the relationship between b and C1 error in this sixth example . In the sixth embodiment, is rotated by the drive means information recording medium using a recording layer Ag-In-Sb-Te system 2.8m / s, 2.6m / s, at each linear velocity of 2.4 m / s Then, an EFM modulation signal having a clock frequency of 8.64 MHz was recorded on the information recording medium by the recording means by the PWM recording method. The information recording medium is composed of a heat resistant protective layer made of a 190 nm thick ZnS / SiO 2 layer, a 18 nm thick Ag—In—Sb—Te recording layer, and a 25 nm thick ZnS · SiO 2 layer on a substrate made of polycarbonate resin. A heat-resistant protective layer, a reflective heat radiation layer made of an Al alloy having a thickness of 150 nm, and a UV coating layer are provided.

  The recording power at each linear velocity was common, and a = c = 12 mW, e = 6 mW, b = d, and n ′ = 2. The parameters of fp, mp, and op were set to x = 1T, y = 0.5, and z = 0.75T, respectively. If b is too large, the rapid cooling condition breaks down and a stable amorphous mark cannot be recorded. On the other hand, if b is too small, it is difficult to increase the temperature, and it becomes difficult to record information with the same a, c, or e, which hinders sensitivity. In this embodiment, it can be seen that the optimum b condition can be obtained by controlling the b value by detecting an error.

The first reference form is the information recording / reproducing method of the first and second embodiments, in which the recording power is sequentially changed with respect to the information recording medium by the recording means in the information recording / reproducing apparatus. Information is recorded in a test pattern, and the recorded information is reproduced from an information recording medium by a reproducing means, and a recording signal amplitude (from an unrecorded part) corresponding to the recording power P from the reproducing means is reproduced by a monitoring means. The difference between the level of the reproduced signal and the level of the reproduced signal from the recording unit) m is monitored, and the gradient g (P) normalized by the recording power setting means is g (P) = (Δm / m) (ΔP / P)
ΔP: Minute change amount in the vicinity of P Δm: By obtaining a small change amount corresponding to ΔP in the vicinity of m, and evaluating the excess or deficiency of the recording power based on the standardized gradient g (P). Determine and set the optimum recording power.

Further, the second reference form is the information recording / reproducing method of the first and second embodiments , in which the recording power P is sequentially changed with respect to the information recording medium by the recording means in the information recording / reproducing apparatus. Information is recorded in a pattern consisting of a recording portion and a recording section, the information recorded by the recording means is reproduced from the information recording medium by the reproducing means, and the recording signal amplitude corresponding to the recording power P from the reproducing means is reproduced by the monitoring means. (Difference between the level of the reproduced signal from the unrecorded portion and the level of the reproduced signal from the recorded portion) m is monitored, and the standardized gradient g (P) is set to g (P) = ( Δm / m) (ΔP / P)
ΔP: Slight change amount in the vicinity of P Δm: A specific value S selected from 0.2 to 2.0 is obtained by an expression of a minute change amount corresponding to ΔP in the vicinity of m, and is normalized. The recording power Ps such that the inclination g (P) coincides with S is detected, and the optimum recording power is set by multiplying Ps by 1.0 to 1.7.

In these first and second reference forms, m and P, which are likely to occur between individual information recording / reproducing apparatuses, are used by using ratios of change rates normalized by the relationship between the recording signal amplitude m and the recording power P. The optimum recording power can be set without being affected by both offsets, and optimum recording with practically sufficient accuracy (± 5%) for an information recording / reproducing device such as an optical disc device designed especially for mass production. Power can be set easily. Here, the recording power P indicates the power level of a or c in FIG. 1, and the power level of e may be set to a fixed value or a power level proportional to a or c.

Next, the theoretical background of the first and second reference embodiments will be described. A standard recording signal amplitude m ₀ observed by a standard information recording / reproducing apparatus and a standard recording power P ₀ are expressed by the following relational expression m ₀ = m ₀ (P ₀ )
The ratio g ₀ (P ₀ ) obtained by further normalizing the change amounts Δm ₀ and ΔP ₀ corresponding to m ₀ and P ₀ respectively with m ₀ and P ₀ as a function of P ₀ Expression g ₀ (P ₀ ) = (Δm ₀ / m ₀ ) (ΔP ₀ / P ₀ )
It is represented by Here, g ₀ (P ₀ ) indicates a standardized slope of m ₀ with respect to P ₀ , and is therefore referred to as “standardized slope”.

The advantage of using this “normalized slope” is the relationship between the recording power P and the general recording signal amplitude m deviating from the standard (with offset) as given by the following equation: m (P) = km ₀ (P), P = qP ₀
k, q: It has universality even for non-zero constants. The following simple calculation formula g (P) = (Δm / m) / (ΔP / P)
= {Δ (km ₀ ) / (km ₀ )} / {Δ (qP) / (qP)}
= (Δm ₀ / m ₀ ) / (ΔPw / Pw) = g ₀ (P ₀ )
As will be clear, as long as the normalized slope value g (P) is observed, it is always the same as the standard value g ₀ (P ₀ ).

  That is, since the value of g (P) is a numerical value that is stored regardless of the presence or absence of the offsets of m and P, it can be said that it is a numerical value that accurately and universally represents the state of excess or deficiency in recording power. Accordingly, if information is recorded by setting the recording power P so that the gradient value g (P) standardized by the information recording / reproducing apparatus becomes the same, the information can be recorded by a different information recording / reproducing apparatus. Information can always be recorded in the same recording state, which is extremely convenient for industrial applications where importance is placed on the reproducibility of information recording.

  Naturally, as the value of the recording power P increases, the value of m saturates and g (P) generally converges to zero. Therefore, in order to more accurately find the state of recording excess or deficiency, g The value of (P) is set in the range of 0.2 to 2.0, preferably 0.7 to 1.7, and the corresponding value of P is 1.0 to 1.7 times, preferably It is effective to set the optimum recording power at 1.0 to 1.5 times.

Next, a specific method for obtaining the normalized inclination g will be described.
The general formula for obtaining the normalized gradient g is expressed as follows: g (P) = (Δm / m) as an expression that the minute change in the recording signal amplitude m is Δm corresponding to the minute change ΔP in the recording power P. ) / (ΔP / P)
It is represented by

The practical formulas for obtaining the standardized gradient g are i, i + 1, the recording power of the first test recording is P (i), P (i + 1), and the recording signal amplitude is m (i), m (i + 1). Then g [{P (i) + P (i + 1)} / 2]
= [{M (i + 1) -m (i)} / {m (i + 1) + m (i)}] /
[{P (i + 1) -P (i)} / {{P (i + 1) + P (i)}]
It is represented by

Other practical formulas for obtaining the standardized gradient g are as follows: the recording power of the i−1, i, i + 1th test recording is P (i−1), P (i), P (i + 1), the recording signal When the amplitude is m (i−1), m (i), m (i + 1) and P (i) = {P (i + 1) + P (i−1)} / 2, the following equation g (i) = [{M (i + 1) -m (i-1)} / {m (i + 1) + m (i-1)
}] / [{Pw (i + 1) -Pw (i-1)} / {{Pw (i + 1)
+ Pw (i-1)}]
It is represented by

FIG. 12 shows an example of the function and effect of the first reference embodiment . The relationship between the recording signal amplitude m and the recording power P recorded and reproduced by three different information recording / reproducing apparatuses similar to this embodiment is that the saturation value of the recording signal amplitude is 0.60 and 075, respectively, as shown in FIG. , 0.50, and therefore, different curves m (0), m (1), m (2) are drawn, and the optimum recording power that is the target is obtained even with a fixed recording signal amplitude level as a reference. It cannot be determined uniquely, and variation occurs corresponding to the deviation of the curves m (0), m (1), and m (2). Further, when P> 12 mW, since the three curves (0), m (1), and m (2) are substantially parallel lines, it is impossible to even set a common reference for the recording signal level. .

Regarding the relationship between the standardized gradient g and the recording power P in the first reference embodiment, the result of calculating the standardized gradient g using the above definition formula is the curves (0), m (1), m (2) is completely overlapping. Accordingly, when the recording power giving a predetermined determination level, for example, g _set = 0.25 is determined using the standardized curve of the inclination g, even if the information recording / reproducing apparatuses are different, all the unique recording power P _set varies. And can be set reliably. That is, in this embodiment, an optimum recording power can be reliably set by performing test recording on a recordable optical information recording medium, and an excessive recording power is required for an erasable optical information recording medium. Information can be recorded without damaging the recording film by irradiating the light, and the number of erasable times can be increased, and the reliability of information recording can be improved. In addition, the optimum recording power can be set automatically without being affected by variations such as the recording signal level being the same even with the same recording power among the individual optical information recording / reproducing devices, thereby reducing the cost. The optical information recording / reproducing apparatus can be realized. This shows the excellent operational effect of the first reference embodiment, and shows that the versatility is high and the recording power setting accuracy is excellent.

Thus, in the first reference embodiment, the information recording medium is irradiated with electromagnetic waves to cause a phase change in the recording layer of the information recording medium, and information is recorded on and reproduced from the information recording medium. In the rewritable information recording / reproducing method, information is test-recorded in a pattern composed of an unrecorded portion and a recorded portion while the recording power P is sequentially changed with respect to the information recording medium, and the test-recorded information is reproduced. Then, the recording signal amplitude m corresponding to the recording power P is monitored, and the standardized gradient g (P) is expressed as g (P) = (Δm / m) / (ΔP / P).
ΔP: Minute change amount in the vicinity of P Δm: By obtaining a small change amount corresponding to ΔP in the vicinity of m, and evaluating the excess or deficiency of the recording power based on the standardized gradient g (P). Since the optimum recording power is determined and set, even if the information recording / reproducing device is different, all the unique recording power can be set reliably, and the number of erasable times can be increased and the recording reliability can be improved. It is highly versatile and has excellent recording power setting accuracy.

FIG. 13 shows an example of the function and effect of the second reference embodiment. The relationship between the recording signal amplitude m and the recording power P and the relationship between the standardized gradient g and the recording power P in this embodiment are the same as those in the first reference embodiment. In the first reference form, when the optimum recording power is set, the value of the normalized gradient g is naturally small in the region of P> 13 mW where the recording signal amplitude m is saturated with respect to the recording power. , There is a concern that the change to P becomes gradual and becomes susceptible to disturbance and noise, and the detection accuracy of P decreases. That is, in order to increase the detection accuracy of P, it is better to use a condition where the value of g is large and the change with respect to P is large (the inclination is large).

In the second embodiment, the effect of the example in which S = 10 is shown as a specific value S in FIG. 13, and a method for detecting a recording power whose normalized gradient g value matches S as Ps. The effect of is shown. Since Ps is smaller than the actual optimum recording power P _OPT , P _OPT is set by multiplying Ps by 1.20 in this example. The specific value S may be selected from 0.2 to 2.0 so that the influence of noise is reduced, and the recording power Ps corresponding to the set value S can be detected with high accuracy. The deviation of the recording power Ps from the optimum recording power P _{OPT is set} to an appropriate value in the range of 1.0 to 1.7 times, and this value is multiplied by Ps to obtain the optimum recording power P _OPT. do it. Therefore, the optimum recording power can be set with higher accuracy.

Thus, in the second reference embodiment, the information recording medium is irradiated with electromagnetic waves to cause a phase change in the recording layer of the information recording medium, and information is recorded on and reproduced from the information recording medium. In the rewritable information recording / reproducing method, information is test-recorded in a pattern composed of an unrecorded portion and a recorded portion while the recording power P is sequentially changed with respect to the information recording medium, and the test-recorded information is reproduced. Then, the recording signal amplitude m corresponding to the recording power P is monitored, and the standardized gradient g (P) is expressed as g (P) = (Δm / m) / (ΔP / P).
ΔP: Slight change amount in the vicinity of P Δm: A specific value S selected from 0.2 to 2.0 is obtained by an expression of a minute change amount corresponding to ΔP in the vicinity of m, and is normalized. Since the recording power Ps whose inclination g (P) coincides with S is detected and the optimum recording power is set by multiplying Ps by 1.0 to 1.7, the optimum recording power is set with higher accuracy. Therefore, the information recording / reproducing apparatus can be reduced in cost.

In the third reference form, in the first or second reference form, x, y, z variable means for changing x, y, z in accordance with the linear velocity of the information recording medium is provided, and the information recording medium is a compact disc. Rotate the information recording medium at a double speed (2.4-2.8 m / s) of the standard linear speed of a compact disc at 1x speed, which is rotated at a standard linear speed of 1.2-1.4 m / s. By changing the x, y, z by the x, y, z variable means at the double speed, the same information recording medium can be used at the double speed or at the double speed. The x, y, z variable means sets x, y, z to 0.5T ≦ x ≦ 2T, 0.4 ≦ y ≦ 0.6, and 0.5T ≦ z ≦ 1T as described above at the double speed. At double speed, x, y, and z are set to 1T ≦ x ≦ 1.75T, 0.4 ≦ y ≦ 0.6, and 0.5T ≦ z ≦ 1T.

In the first reference example, in the third reference embodiment, the x, y, z variable means sets x, y, z to optimum values, that is, x is 1T, y is 0.5T, and at double speed, In this case, z is set to 0.5T, and x is set to 1T, y is set to 0.5T, and z is set to 0.5T at 1 × speed.

  Here, the pulse part fp raises the temperature of the recording layer of the phase change information recording medium above the melting point to form the top part of the recording mark, and the multi-pulse part mp raises the temperature of the recording layer to raise the intermediate part of the recording mark. The pulse portion op cools the recording layer to form the rear end of the recording mark, and if the linear velocity of the phase change information recording medium is varied, the amount of electromagnetic radiation applied to the phase change information recording medium can be reduced. Since the temperature rises above the melting point of the recording layer and the subsequent cooling rate changes, changing the x, y, z according to the linear velocity of the information recording medium changes the linear velocity of the information recording medium. However, x, y, and z can be set appropriately to record and rewrite high-quality signals stably, and the same information recording medium can be used at 1 × speed or 2 × speed.

  In particular, if x is changed in accordance with the linear velocity of the information recording medium, the leading portion of the recording mark can be recorded and rewritten with high quality and stability on the same information recording medium at both 1 × speed and 2 × speed. Further, if z is changed in accordance with the linear velocity of the information recording medium, the rear end portion of the recording mark can be recorded and rewritten with high quality and stability with respect to the same information recording medium at the 1 × speed and at the 2 × speed. . Furthermore, by changing x, y, and z according to the linear velocity of the information recording medium, the entire recording mark can be recorded and rewritten with high quality and stability on the same information recording medium at 1 × speed and 2 × speed. Can do.

FIG. 15 shows the measurement results of the number of mark and space recordings and jitter at 1 × speed in the first reference example. From this figure, in the first reference example, jitter increases as the number of marks and spaces recorded at 1 × speed increases, but x, y, and z depend on the linear velocity of the information recording medium as described above. As a result, the jitter can be kept below a predetermined allowable level even if the number of times of recording increases to some extent.

As described above, in the third reference embodiment, in the information recording / reproducing methods of the first and second embodiments , x is set to 1T ≦ x ≦ 1.75T, so that the phase change information recording medium is applied with the PWM recording method. In the method of recording information, it is possible to stably record and rewrite a high-quality signal, and when the information recording medium is moved at the reference linear speed, and the information recording medium is moved at twice the reference linear speed. In both cases, the leading end side of the recording unit can be recorded and rewritten with high quality and stability.

In the third reference embodiment, in the information recording / reproducing method of the first and second embodiments , z is set to 0.5T ≦ z ≦ 1T, so that information is recorded on the phase change information recording medium by the PWM recording method. The method can record and rewrite high-quality signals stably and record both when the information recording medium is moved at the reference linear velocity and when the information recording medium is moved at twice the reference linear velocity. It is possible to stably record and rewrite the rear end side of the portion with high quality.

In the third reference embodiment, in the information recording / reproducing method of the first and second embodiments , x, y, z are set to 1T ≦ x ≦ 1.75T when the information recording medium is moved at the reference linear velocity of the compact disc. 0.4 ≦ y ≦ 0.6 and 0.5T ≦ z ≦ 1T, so that a signal of good quality can be stably recorded and rewritten in the method of recording information on the phase change information recording medium by the PWM recording method. In addition, both when the information recording medium is moved at the reference linear speed of the compact disk and when the information recording medium of the compact disk is moved at a speed twice the reference linear speed, the entire recording unit is stable with high quality. Can be recorded and rewritten.

It is a wave form diagram showing typically a pulse waveform of a recording wave in an example of an embodiment of the present invention about an example of n '= 1-3 by 3T signal. It is a characteristic view which shows the relationship between b and C1 error in case of b = d in the example of embodiment of this invention. It is a characteristic view which shows the relationship between m and a and e in case of a = c in the example of embodiment of this invention. It is a characteristic view which shows the relationship between (beta) and a and e in case of a = c in the example of embodiment of this invention. It is sectional drawing which shows the information recording medium of the embodiment of this invention. FIG. 10 is a characteristic diagram showing the influence of jitter on the power margin after 1000 overwriting iterations of x in the embodiment of the present invention. It is a wave form diagram which shows the example of a recording waveform of the embodiment of this invention. FIG. 6 is a characteristic diagram showing the relationship between the reflectance calculated from the reflected light intensity of the information recording medium and a preferred value of x in the embodiment of the present invention. It is a characteristic view which shows the relationship between y and jitter in the example of embodiment of this invention. It is a characteristic view which shows the relationship between z and jitter in the example of an embodiment of the present invention. It is a wave form diagram which shows the example of a recording waveform of the embodiment of this invention. It is a figure which shows the example of the effect of the embodiment of the invention of Claim 22. It is a figure which shows the example of the effect of the embodiment of the invention of Claim 23. It is a block diagram which shows a part of said embodiment. It is a characteristic view showing the measurement results of the number of times of recording of marks and spaces and the jitter at the time of 1 × speed in the examples of the inventions according to claims 24 to 26.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 2, 4 Heat-resistant protective layer 3 Recording layer 5 Reflection heat radiation layer 11 Information recording medium 13 Recording / reproducing pickup

Claims (28)

  In an information recording / reproducing method in which a phase change is caused in a recording layer of the information recording medium by irradiating the information recording medium with an electromagnetic wave, information is recorded on and reproduced from the information recording medium, and rewriting is possible. When a signal is modulated and information is recorded on the information recording medium by a PWM recording method, a recording wave at the time of recording or rewriting a signal having a predetermined signal width after modulation is a continuous electromagnetic wave having a first power level. And a recording wave pulse train when recording or rewriting one signal having a predetermined signal width after modulation, and a pulse width having a first time width and a second power level, and a total time width of the clock time. A multi-pulse unit in which a low level pulse having a third power level and a high level pulse having a fourth power level are alternately provided at a predetermined duty ratio for a predetermined number of times. , An electromagnetic wave pulse train including a second time width and a pulse portion having a fifth power level, and each of the first time width, the duty ratio, and the second time width is set according to a linear velocity. An information recording / reproducing method.   In an information recording / reproducing method in which a phase change is caused in a recording layer of the information recording medium by irradiating the information recording medium with an electromagnetic wave, information is recorded on and reproduced from the information recording medium, and rewriting is possible. When recording information by modulating a signal and performing PWM recording on the information recording medium, a recording wave when recording or rewriting a zero signal whose modulated signal width is nT (T is a clock time) Is a continuous electromagnetic wave of power level e, and a recording wave pulse train when recording or rewriting one signal whose modulated signal width is nT is a total of T and a pulse part fp having a time width x and a power level a. A multi-pulse unit mp in which a low level pulse of power level b and a high level pulse of power level c having a time width of An electromagnetic pulse train composed of a pulse part op having a time width z and a power level d, and x, y, z are set to 0.5T ≦ x ≦ 2T, 0.4 ≦ y ≦ 0.6, and 0.5T ≦ z ≦ 1T. , N ′ is a positive integer satisfying n ′ ≦ n, and (a and c)> e> (b and d).   In an information recording / reproducing apparatus capable of causing a phase change in a recording layer of the information recording medium by irradiating the information recording medium with an electromagnetic wave, recording and reproducing information on the information recording medium, and rewriting the information recording medium. A recording means for modulating the signal and recording information on the information recording medium by the PWM recording method and a recording control means for controlling the recording means are provided, and the information is recorded on the information recording medium by modulating the signal by the PWM recording method. When recording, a recording wave at the time of recording or rewriting a signal having a predetermined signal width after modulation is a continuous electromagnetic wave of the first power level, and recording or rewriting one signal having a predetermined signal width after modulation. And a third power level having a total time width of a clock time and a pulse portion having a first time width and a second power level. An electromagnetic wave pulse train comprising a multi-pulse portion in which a low level pulse and a high level pulse of a fourth power level are alternately repeated a predetermined number of times at a predetermined duty ratio, and a pulse portion having a second time width and a fifth power level And the recording control means sets each of the first time width, the duty ratio, and the second time width in accordance with a linear velocity.   In an information recording / reproducing apparatus capable of causing a phase change in a recording layer of the information recording medium by irradiating the information recording medium with an electromagnetic wave, recording and reproducing information on the information recording medium, and rewriting the information recording medium. Recording means for modulating a signal and recording information on the information recording medium by a PWM recording method is provided. This recording means records or rewrites a zero signal whose modulated signal width is nT (T is a clock time). The recording wave when performing recording is a continuous electromagnetic wave of power level e, and the recording wave pulse train when recording or rewriting one signal whose modulated signal width is nT is a pulse portion having a time width x and a power level a. fp, a low level pulse of power level b and a high level pulse of power level c having a total time width of T are alternately (n−n ′) times with a duty ratio y. An electromagnetic wave pulse train comprising a multi-pulse part mp, a pulse part op having a time width z and a power level d, and x, y, z are 0.5T ≦ x ≦ 2T, 0.4 ≦ y ≦ 0.6, 0. 5. An information recording / reproducing apparatus characterized in that 5T ≦ z ≦ 1T, n ′ is a positive integer satisfying n ′ ≦ n, and (a and c)> e> (b and d).   3. The information recording / reproducing method according to claim 1, wherein a method for modulating a signal to be recorded is an EFM modulation method or an improved modulation method thereof, and n '= 2.   5. The information recording / reproducing apparatus according to claim 3 or 4, wherein the recording means modulates a signal to be recorded by an EFM modulation method or an improved modulation method thereof and sets n '= 2.   3. The information recording / reproducing method according to claim 1, wherein the signal is recorded and / or rewritten by controlling the power level of the electromagnetic wave so that e / a or e / c is not less than 0.3 and not more than 0.7. An information recording / reproducing method.   5. The information recording / reproducing apparatus according to claim 3, wherein the signal is recorded and / or rewritten by controlling the power level of the electromagnetic wave so that e / a or e / c is not less than 0.3 and not more than 0.7. An information recording / reproducing apparatus comprising:   3. The information recording / reproducing method according to claim 1, wherein x, y, z and a power level of an electromagnetic wave for reproducing a signal are determined based on a reflected wave intensity at the time of reproducing the information recording medium. Information recording and playback method.   5. The information recording / reproducing apparatus according to claim 3, further comprising means for determining x, y, z and a power level of an electromagnetic wave for reproducing a signal based on a reflected wave intensity at the time of reproducing the information recording medium. An information recording / reproducing apparatus.   An information recording medium used in the information recording / reproducing method according to claim 1 or 2, or the information recording / reproducing apparatus according to claim 3 or 4, comprising at least a substrate, a heat-resistant protective layer, and a recording layer. Information recording medium.   12. The information recording medium according to claim 11, further comprising a reflective heat dissipation layer.   12. The information recording medium according to claim 11, wherein the heat-resistant protective layer is provided on both sides so as to sandwich the recording layer.   12. The information recording medium according to claim 11, wherein the heat-resistant protective layer disposed between the substrate and the recording layer has a thickness of 500 to 2500 angstroms.   12. The information recording medium according to claim 11, wherein when the heat-resistant protective layer is provided on the recording layer, the heat-resistant protective layer has a thickness of 100 to 1500 angstroms. .   12. The information recording medium according to claim 11, wherein main constituent elements of the recording layer are Ag, In, Sb, and Te.   12. The information recording medium according to claim 11, wherein the recording layer has a thickness of 100 to 1000 angstroms.   12. The information recording medium according to claim 11, wherein the substrate is made of glass, ceramic, or resin. 12. The information recording medium according to claim 11, wherein the material of the heat-resistant protective layer is a metal oxide such as SiO, SiO ₂ , ZnO, SnO ₂ , Al ₂ O ₂ , TiO ₂ , In ₂ O ₂ , MgO, or ZrO _2. Nitrides such as Si ₂ N ₄ , AlN, TiN, BN and ZrN, sulfides such as ZnS, In ₂ S ₃ and TaS ₄ , carbides such as SiC, TaC, B ₄ C, WC, TiC and ZrC, An information recording medium characterized by being diamond carbon or a mixture thereof.   13. The information recording medium according to claim 12, wherein the reflective heat radiation layer is made of a metal material such as Al or Au, or an alloy thereof.   13. The information recording medium according to claim 12, wherein the thickness of the reflective heat radiation layer is 300 to 2000 angstroms.   5. The information recording / reproducing apparatus according to claim 3, wherein the information recording medium is rotated at a rotational linear velocity of 1.2 m / s or more and 5.6 m / s or less during information recording.   An information recording medium used in the information recording / reproducing method according to claim 1 or 2, or the information recording / reproducing apparatus according to claim 3 or 4, wherein the rotation is 1.2 m / s or more and 5.6 m / s or less during information recording. An information recording medium that is rotated at a linear velocity.   23. The information recording / reproducing apparatus according to claim 22, further comprising means for temporarily storing a part of information to be recorded.   25. The information recording / reproducing apparatus according to claim 24, further comprising means capable of making the rotational linear velocity of the information recording medium during information recording higher than the rotational linear velocity of the information recording medium during information reproduction. Information recording / reproducing apparatus.   3. The information recording / reproducing method according to claim 1, wherein x is 1T ≦ x ≦ 1.75T.   3. The information recording / reproducing method according to claim 1, wherein z is set to 0.5T ≦ z ≦ 1T.   3. The information recording / reproducing method according to claim 1, wherein when the information recording medium is moved at a reference linear velocity of the compact disc, x, y, z are set to 1T ≦ x ≦ 1.75T, 0.4 ≦ y ≦ 0. 6. An information recording / reproducing method, wherein 0.5T ≦ z ≦ 1T.

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