Optical recording medium, recording method of optical recording medium and recorder of optical recording medium

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

The present invention is a recording method of an optical recording medium capable of recording or reproducing a high-density, high-transfer rate signal by irradiating a plurality of recording thin films formed on a substrate with a high-energy beam such as a laser beam. , And the recording device.

【0002】

[Conventional technology]

In recent years, there has been active research and development of commercialization of optical recording media capable of recording, reproducing and erasing information, and rewriting-type optical recording media capable of recording high-quality moving images with high density and high transfer rate. It is done. As a rewritable optical recording medium, information is provided on a disk-shaped substrate, for example, a Te or Se-based chalcogenide thin film such as Ge-Sb-Te or In-Se, or a semimetal thin film such as In-Sb. A phase change optical recording medium provided as a layer is known. Further, a photomagnetic recording medium having a metal thin film such as Fe-Tb-Co as an information layer is known. There is also a write-once optical recording medium using a dye material.

【0003】

In the phase change light recording medium, for example, the information layer made of the phase change material is instantaneously irradiated with laser light focused on a spot of submicron order size, and the irradiated portion is locally heated to a predetermined temperature. The irradiated portion is converted to a crystalline state when the reached temperature is equal to or higher than the crystallization temperature, and is converted to an amorphous state when the temperature exceeds the melting point and is melted and then rapidly cooled. By defining either the amorphous state or the crystalline state as the recording state or the erasing state (unrecorded state) and forming the pattern corresponding to the information signal, reversible information recording or erasing is performed. .. The optical characteristics differ between the crystalline state and the amorphous state, and the signal can be reproduced by optically detecting the change in reflectance or the change in transmittance by utilizing the difference.

【0004】

In the photomagnetic recording medium, for example, the photomagnetic recording thin film is irradiated with the focused laser light and locally heated to a predetermined temperature. Information is recorded or erased by applying a magnetic field at the same time as heating and reversing the magnetization direction of the magneto-optical recording thin film according to the information. Mark length recording is a method for recording high-density data on an optical recording medium. In the mark length recording, various mark lengths are recorded at various intervals (spaces), and recording information is assigned to both the mark length and the space length.

【0005】

When recording on a phase change recording medium by the mark length recording method, the amorphous region is defined as a mark, and the crystalline region is defined as a space. In order to form a mark on this recording medium, a method of irradiating the information layer with a laser beam whose irradiation intensity is modulated into a plurality of pulses is generally used. For example, as shown in FIG. 7, a data signal (b) synchronized with the period T of the reference clock (a) of the information signal used when recording the information signal on the recording medium is recorded as a recording pulse (b) composed of a plurality of pulse trains. It is converted to c), and the laser beam is modulated by the recording power (d) based on this recording pulse. By this modulation method, mark formation can be facilitated.

【0006】

[Problems to be Solved by the Invention]

However, when the recording power is modulated between the peak power and the bias power by the laser drive circuit, the modulated waveform requires a constant rise time and fall time. When the transfer rate is further increased, it is necessary to shorten the period of the reference clock of the signal. For example, as shown in FIG. 8, as the period t of the reference clock (a) becomes shorter, the width of the individual pulses constituting the recording pulse (c) also becomes shorter. When the width of each pulse becomes shorter than the sum of the rise time and fall time of the laser drive circuit, the recorded waveform is modulated by compensating for the peak power level and bias power level, as shown in Fig. 8 (d). This cannot be done, and a power difference occurs between the starting pulse, the intermediate pulse, and the trailing pulse. Further, at a high transfer rate, pulse modulation may not be possible and a single pulse may be formed. For this reason, it becomes difficult to obtain a rapidly cooled state in which the irradiated portion melted beyond the melting point of the information layer can be converted into an amorphous state, and it becomes difficult to form a sufficient mark.

【0007】

On the other hand, in order to record at higher density, it is necessary to shorten the lengths of the marks and spaces to be recorded. However, as the length of the space becomes shorter, the heat at the end of the recorded mark affects the temperature rise at the beginning of the next recorded mark, or the heat at the beginning of the next recorded mark is the cooling process of the immediately preceding mark. So-called thermal interference occurs, such as giving to. Due to this thermal interference, the position of the edge of the front end or the rear end of the recorded mark is moved from an appropriate position, which causes a deterioration in the bit error rate during reproduction.

【0008】

Therefore, an object of the present invention is to compensate for a quenching state capable of converting to an amorphous state by using a recording pulse drive composed of a plurality of pulse trains even in an optical recording medium for recording at a high density and a high transfer rate, and to perform edge shift. It is an object of the present invention to provide a recording method of an optical recording medium capable of forming a small recording mark, and an optical recording apparatus.

【0009】

[Means for solving problems]

Light intensity using a pulse consisting of a start pulse for forming the start region of the mark, an intermediate pulse train for forming the middle portion of the mark, and a rear pulse for forming the rear end region of the mark. The period of the intermediate pulse train to be modulated is made longer than the period of the reference clock of the information signal used when recording the information signal, and the position of the front edge of the starting pulse is at least the length of the mark to be recorded and immediately before. As a recording method of an optical recording medium that changes according to the length of the space and changes the position of the trailing edge of the trailing end pulse according to at least the length of the mark to be recorded and the length of the space immediately after it. There is.

【0010】

Further, the optical recording medium is provided with a cycle identifier for identifying the cycle of the intermediate pulse train, the information of the identifier is demodulated, and the intermediate pulse train according to the demodulated signal is used for recording.

【0011】

Further, when the period of the reference clock is longer than a predetermined period, a method of recording using an intermediate pulse train of the reference clock period is used.

【0012】

Alternatively, a start pulse for forming the start region of the mark, an intermediate pulse train for forming the middle portion of the mark, a pulse generating means for generating the rear end pulse for forming the rear end region of the mark, and light. A cycle determination means for determining the information of the cycle identifier for identifying the period of the intermediate pulse train provided in the recording medium and outputting the determination signal, and a frequency dividing means for dividing the period of the reference clock according to the determination signal, at least. From the data length detecting means that detects the length of the recording mark, the length of the space immediately before the recording mark, and the length of the space immediately after the recording mark and outputs a data length detection signal, and the length detection signal. , The timing control means for setting the front edge and the rear edge delay amount of the start end pulse and generating the delay start pulse and the delay rear end pulse, and the output signal of the frequency dividing means and the output of the timing control means. The configuration is a recording device for an optical recording medium including a pulse synthesizing means for synthesizing signals and outputting a recording pulse, and a laser driving means for modulating the intensity of an optical beam based on the recording pulse.

【0013】

Further, an optical recording medium further provided with a cooling pulse section that reaches the bottom power level immediately after the rear end pulse, and a section control circuit that changes the length of this cooling pulse section according to the output signal of the data length detecting means. It has the configuration of the recording device.

【0014】

Further, the recording device of the optical recording medium is configured to include a frequency dividing means for outputting an intermediate pulse train according to the output signal of the cycle determining means.

【0015】

Alternatively, when the period of the reference clock is longer than a predetermined period, the frequency dividing means is configured as a recording device of an optical recording medium that outputs an intermediate pulse of the reference clock period.

【0016】

Further, an information layer for recording the information signal as the length of the mark and the space is provided, and the start pulse for forming the start region of the mark on the information layer and the intermediate pulse for forming the intermediate portion of the mark are provided. , An optical recording medium for recording using a multi-pulse consisting of a rear-end pulse for forming a rear-end region of a mark, an identifier for identifying the period of the intermediate pulse, and a position of the start-end pulse. Alternatively, the position of the front edge of the start pulse is changed at least according to the length of the mark to be recorded and the length of the space immediately before, and the position of the rear end pulse or the position of the rear edge of the rear end pulse. The position is configured as an optical recording medium having at least an identifier related to a start-end recording condition that changes according to the length of the mark to be recorded and the length of the space immediately after the recording.

【0017】

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

【0018】

(Embodiment 1) FIG. 2 is a cross-sectional view showing an optical recording medium used in the present embodiment. In FIG. 2, the optical recording medium 201 includes an information layer 203 on the substrate 202. As the substrate 202, a resin material such as polycarbonate and glass are used. On the surface of the substrate, a guide track having a certain depth for tracking an optical beam, an uneven pit for addressing, and an uneven pit corresponding to management information of an optical recording medium are formed.

【0019】

There are two types of materials that make up the information layer 203: a write-once type that can be recorded only once, and a rewrite type that can be re-recorded. As a write-once recording material, a material that utilizes a phase change such as Te-O or Te-O-Pd, that is, a signal is recorded by utilizing the difference in optical constants between amorphous and crystal. In addition, there are recording materials that perform recording by utilizing diffraction due to a change in shape of an organic dye material or the like, or a change in the amount of reflected light or the amount of transmitted light due to the presence or absence of an information layer. The rewrite type includes a phase change material that undergoes a phase change between amorphous and crystals, and a magneto-optical material that utilizes the magneto-optical effect. As the phase change material, a Ge-Sb-Te-based material, an In-Sb-Te-based material, or the like can be used. Further, as the magneto-optical material, a material such as Tb-Fe-Co can be used.

【0020】

A protective plate 204 for protecting the information layer is provided on the information layer 203. As the material of the protective plate 204, the same material as the substrate 202 or a flat plate made of metal or the like can be used. In the data area 205 for recording the information signal on the information layer 203, marks of various lengths in which the recording information is assigned to both the mark length and the space length are recorded at various intervals (spaces).

【0021】

A management area 206 is provided at a specific position on the optical recording medium 201. The management area 206 is a recording that forms the start end portion of the mark to be recorded with respect to the information layer 203 according to the information regarding the reference clock cycle of the mark to be recorded and the length of the mark to be recorded and the length of the space immediately before the mark. The rear end for changing the recording end position that forms the trailing end of the mark to be recorded, depending on the information about the start recording conditions for changing the start position and the length of the mark to be recorded and the length of the space immediately following it. Record information about recording conditions. Further, the form of the management area may be formed as an uneven pit shape, a recording mark shape same as the data area, a bar code shape, or a combination of these forms. As a result, a recording pulse can be set according to the transfer rate of the information to be recorded on the information layer 203, and a stable recording state can be obtained.

【0022】

The operation of the device that records information on the optical recording medium 201 according to an instruction from an external device will be described with reference to the block diagram of FIG. 1 and the timing charts of FIGS. 3 and 4.

【0023】

Data 1 (Fig. 3b), which is information to be recorded at a timing synchronized with the reference clock (Fig. 3a) of the information signal used when recording the information signal, is input. The data 1 is input to the start-end pulse generation circuit 3, the intermediate pulse generation circuit 4, and the rear-end pulse generation circuit 5 that constitute the basic pulse generation unit 2. In the start pulse generation circuit 3, a start pulse 11 (FIG. 3c) having a width of one cycle of the clock is generated at the start portion of the Hi period of the data 1. In the intermediate pulse generation circuit 4, an intermediate pulse 12 (FIG. 3 g) having a clock period is generated with a length 4 clocks shorter than the clock length of the mark recorded at the intermediate position of the mark. However, when the mark length is 6 clocks or less, the intermediate pulse signal 12 is not generated. In the rear-end pulse generation circuit 5, a rear-end pulse 13 (FIG. 3d) having a clock cycle width is generated at the rear-end portion of the Hi period of the data 1.

【0024】

In the present embodiment, the input data 1 has a clock unit length, and a signal having a Hi period and a Lo period of 3 to 14 cycles of the clock, such as (8-16) modulated signal, is used. Data is used, the Hi period of the data is used as a mark on the optical recording medium, and the Lo period is used as a mark length recording that is recorded corresponding to a space. Further, for simplification of explanation, it is assumed that the start end recording condition and the rear end recording condition are changed by detecting the case where the space length and the mark length are 3T and 4T.

【0025】

Further, the data 1 is input to the front space detection circuit 7, the recording mark detection circuit 8, and the rear space detection circuit 9 that constitute the data length detection unit 6. The front space detection circuit 7 detects 3 clocks and 4 clock width data of the Lo period of data 1, that is, 3T and 4T spaces, and sends a front space length detection signal 14 to the start end start position setting circuit 20. Further, the recording mark detection circuit 8 sends the recording mark length detection signal 15 that has detected the length of the recording mark to the start end start position setting circuit 20 and the rear end position setting circuit 25. Further, the rear space detection circuit 9 detects 3 clocks and 4 clock width data of the Lo period of the data 1, that is, 3T and 4T spaces, and sends the rear space length detection signal 16 to the rear end position setting circuit 25.

【0026】

Next, a method of reading the recording conditions from the optical recording medium 201 will be described. The optical pick 40 irradiates the control area 206 on the optical recording medium 201 with the laser beam 41, receives the reflected light with the detector 42, converts it into an electric signal, and outputs the detection signal 43. The amplifier 44 amplifies the detection signal 43 and outputs the reproduction signal 45 to the start end recording information demodulation circuit 46, the rear end recording information demodulation circuit 47, and the cycle determination circuit 54. The start-end recording information demodulation circuit 46 demodulates the start-end recording information 48 for recording in the information layer 203 included in the reproduction signal 45. The start record information 48 is stored in the start condition storage circuit 49 corresponding to the information layer.

【0027】

An example of the start storage information of the start condition storage circuit 49 is shown in (Table 1). In the start condition storage circuit 49, there are start end start position parameters (pre-space length, recording mark length) of the information layer 203, and start end start position settings (set value, delay time d1) corresponding thereto. Similarly, the rear end recording information demodulation circuit 47 demodulates the rear end recording information 50 for recording in each information layer included in the reproduction signal 45. The rear end recording information 50 is stored in the rear end condition storage circuit 51 corresponding to the information layer.

【0028】

[table 1]

<img file="JP2003030833A_D0001.tif" />【0029】

An example of the rear end storage information of the rear end condition storage circuit 51 is shown in (Table 2). In the rear end condition storage circuit 51, there are a rear end start position parameter (rear space length, recording mark length) of the information layer 203, and a rear end start position setting (set value, delay time d2) corresponding thereto.

【0030】

[Table 2]

<img file="JP2003030833A_D0002.tif" />【0031】

Next, the start end start position setting circuit 20 determines a parameter based on the front space length detection signal 14 and the recording mark length detection signal 15 for the start end recording information 52, and determines the delay time of the start end pulse from this parameter. decide. The start pulse delay circuit 21 delays the start pulse 11 according to the delay signal 22 output from the start position setting circuit 20, and outputs the delay start pulse 23 (FIG. 3e).

【0032】

As described above, it is possible to output the delay start pulse 23 in which the delay amount is changed according to the length of the recording mark forming the recording mark and the length of the front space. Similarly, the rear end opening rear position setting circuit 25 determines a parameter for the rear end recording information 53 based on the rear space length detection signal 16 and the recording mark length detection signal 15, and the rear end pulse is derived from this parameter. Determine the delay time for. The rear end pulse delay circuit 26 delays the rear end pulse 13 according to the delay signal 27 output from the rear end position setting circuit 25, and outputs the delayed rear end pulse 28 (FIG. 3f). As described above, it is possible to output the delay rear end pulse 28 in which the delay amount is changed according to the length of the recording mark forming the recording mark and the length of the rear space.

【0033】

On the other hand, the cycle determination circuit 54 detects a reference clock for recording on the optical recording medium 201 from the reproduction signal 45, determines whether or not the detected reference clock is equal to or higher than a predetermined value, and outputs the cycle determination signal 55. Output. The intermediate pulse 12 is input to the frequency divider circuit 29. When the reference clock is equal to or higher than a predetermined value with respect to the period determination signal 55, the frequency dividing circuit 29 divides the period of the intermediate pulse and converts it into a pulse having a long period, and multi-pulse signal 30 (FIG. 3h). Is output.

【0034】

Hereinafter, the case where the cycle determination signal 55 is the detected signal of a predetermined value or less will be described. It is assumed that the multi-pulse signal is not generated when the period of the intermediate pulse 12 is divided by 1/2 and the mark length to be recorded is 6T or less. Also, at the odd mark in the 7T ~ 13T mark, one pulse with a pulse width of 1T is generated at 7T, and two pulses with a pulse width of 1T are generated at 9T, and so on. It is generated by gradually increasing the number of pulses.

【0035】

Furthermore, in the case of the 8T mark, one 1T-wide pulse is generated in the middle of the front-end pulse and the rear-end pulse. In the case of a 10T pulse, one pulse is generated at the rear end position of the 1T cycle following the first pulse and one pulse is generated before the 1T cycle of the rear end pulse. In the case of a 12T pulse, one pulse is generated at the rear end position of the 1T cycle following the first pulse and one pulse is generated 1T cycle before the rear end pulse, and a 1T width pulse is generated between the front end pulse and the rear end pulse. Generate one. In the case of a 14T pulse, two pulses are generated at the rear end position every 1T cycle following the first pulse, and two pulses are generated every 1T cycle before the rear end pulse.

【0036】

Next, the OR gate 31 ORs the delay start pulse 23, the delay end pulse 28, and the multi-pulse 30 to generate a recording pulse 32 (FIG. 3i). In addition, FIG. 4 shows a list of recorded pulses generated. 3T and 4T are one rectangular pulse. For recorded pulses of 5T or more, the pulse widths at the start and end ends are 1T, and the interval between the pulse train following the start end pulse and the pulse train before the rear end pulse is 1T period. Furthermore, an interval of 1T or more is secured between each pulse. As a result, the interval between the Hi period and the Lo period in the multi-pulse signal 30 can be sufficiently widened. Further, since the density of the pulse applied to the front end portion and the rear end portion of the recording mark is constant even if the recording mark length changes, a uniform front end edge and a rear end edge can be formed.

【0037】

The laser drive circuit 33 drives the laser 34 according to the recording pulse 32. From the laser 34, the irradiation intensity of the laser beam 41 outputs an emission waveform (Fig. 3j) in which the high level corresponds to the peak power and the low level corresponds to the bias power. Since the pulse interval of the modulated waveform is wider than that of the intermediate pulse of the conventional clock period, the time to reach the peak power and the time to reach the bias power can be secured. Therefore, the laser drive circuit can modulate the irradiation intensity of the laser beam 41 between a predetermined peak power and bias power. By irradiating the information layer 203 with the modulated laser beam 41, a recording mark and a space (FIG. 3k) are formed.

【0038】

By the above operation, the optical recording device of the present embodiment can stably compensate the modulation level even at a high density and a high transfer rate, and further, the recording start position and the recording end position of the mark can be set to desired data. Corresponding marks and spaces can be recorded. Therefore, the mark distortion caused by insufficient cooling and the mark distortion caused by the thermal interference caused by the high density can be reduced, and the jitter of the signal reproduced from the recorded mark of the information layer can be reduced. As a result, it becomes possible to record a signal having a small bit error rate. For data in spaces of 5T or more, a fixed amount of delay is used as an example, but if delay control of the start pulse and trailing pulse is performed for all space lengths, the bit error rate will further increase. It will be improved.

【0039】

Up to this point, the case where the recording mark length and the space length immediately before are detected and the delay control is performed according to this detection result has been taken as an example. If the space length is detected and the delay control of the start end pulse and the rear end pulse is performed according to the detection result, the bit error rate is further improved.

【0040】

Further, the method of determining the recording start position and recording end position of the recording mark by delay-controlling the start end pulse position and the rear end pulse position has been described, but the rear edge position of the start end pulse is fixed and the start end pulse start edge position is delayed. Then, the start edge position of the rear end pulse may be fixed and the end edge position of the rear end pulse may be delayed and controlled.

【0041】

Further, in the present embodiment, the case where the power level of the recording pulse is modulated by the binary level of the peak power and the bias power has been described, but it is applied to various pulses as shown in FIG. 6 depending on the optical recording medium. You may. That is, FIG. 6A is a pulse in which the power level between multiple pulses is set to the bottom power level equal to or lower than the bias power level. FIG. 6B shows a pulse in which the power level immediately after the rear end pulse is set to the bottom power. Alternatively, FIG. 6 (c) is a pulse in which the power level between the multi-pulses and the power level immediately after the rear end pulse are simultaneously set to the bias power or less. As described above, when the power level difference is large, more time is required for the power to rise and fall. However, as shown in the present embodiment, since the interval between each pulse is wide, the time to reach the peak power and the time to reach the bias power can be secured. The laser drive circuit 33 in this case may be set to three values of peak power level, bias power level, and bottom power level.

【0042】

Further, in the pulses shown in FIGS. 6 (b) and 6 (c), the time Tc at which the power level immediately after the rear end pulse becomes the bottom power may be changed. This method of varying the cooling time is controlled according to the recording mark length and the rear space length, similarly to the delay control method of the rear end pulse edge position. In this case, the rear end portion of the recording mark can be further rapidly cooled, and the cooling time can be optimized according to the recording mark length and the rear space length, so that a good rear end mark edge can be obtained. Can be formed.

【0043】

(Embodiment 2) Next, the block diagram of FIG. 9 and FIG. 5 show the pulse generation operation of the optical recording device when the intervals between the start end pulse, the multi-pulse, and the rear end pulse constituting the recording pulse are constant. This will be described using the recorded pulse pattern of. Since the same parts as those in the first embodiment are used for the parts other than the block that generates the pulse, the detailed operation will be omitted.

【0044】

When data 1 is input, the start pulse generation circuit 90 obtains information on the mark length to be recorded from the recording mark length detection signal 15 of the recording mark length detection circuit 8, and in the case of an odd mark length, the clock In the case of one cycle width and even mark length, the start pulse 91 of 1.5T cycle width of the clock is generated. In the intermediate pulse generation circuit 92, an intermediate pulse 93 of a pulse train having a clock period is generated at an intermediate position of the mark with a length 4 clocks shorter than the clock length of the mark to be recorded. However, when the mark length is 6 clocks or less, the intermediate pulse signal 93 is not generated. The rear-end pulse generation circuit 94 obtains information on the mark length to be recorded from the recording mark length detection signal 15, and has one cycle width of the clock in the case of an odd mark length and 1.5T of the clock in the case of an even mark length. The trailing end pulse 95 of the cycle width is generated.

【0045】

On the other hand, the intermediate pulse 93 is input to the frequency dividing circuit 96. The frequency dividing circuit 96 divides the period of the intermediate pulse 93 and converts it into a pulse having a long period, and outputs a multi-pulse signal 97. Further, in the operation of the frequency dividing circuit 96, the recording mark length information is obtained from the recording mark length detection signal 15, and it is assumed that a multi-pulse signal of 6T or less is not generated. In addition, the 7T to 8T marks generate one pulse with a pulse width of 1T, the 9T to 10T marks generate two pulses with a pulse width of 1T, and the 11T to 12T marks generate three pulses with a pulse width of 1T. Pulses are generated, and at the 13T to 14T marks, four pulses with a pulse width of 1T are generated.

【0046】

The delay circuit 98 obtains the recording mark length information from the recording mark length detection signal 15 and passes the multi-pulse signal 97 as it is without delay in the case of an odd-numbered mark length, and in the case of an even-numbered mark. Is delayed by 0.5T cycle and outputs a delayed multi-pulse signal 99.

【0047】

Further, the start pulse delay circuit 21 delays the start pulse 11 according to the delay signal 22 output from the start position setting circuit 20, and outputs the delay start pulse 23. As described above, it is possible to output the delayed start pulse 23 in which the delay amount of the start pulse 91 is changed according to the length of the recording mark forming the recording mark and the length of the front space.

【0048】

Similarly, the rear end opening rear position setting circuit 25 determines a parameter for the rear end recording information 50 based on the rear space length detection signal 16 and the recording mark length detection signal 15, and the rear end pulse is derived from this parameter. Determine the delay time for. The rear end pulse delay circuit 26 delays the rear end pulse 13 according to the delay signal 27 output from the rear end position setting circuit 25, and outputs the delayed rear end pulse 28.

【0049】

As described above, it is possible to output the delayed rear end pulse 28 in which the delay amount of the rear end pulse 95 is changed according to the length of the recording mark forming the recording mark and the length of the rear space.

【0050】

Next, the OR gate 31 ORs the delayed start pulse 23, the delayed trailing pulse 28, and the delayed multipulse 99 to generate the recording pulse 32. Figure 5 shows a list of recorded pulses generated. 3T and 4T are one rectangular pulse. For recorded pulses of 5T or more, odd-numbered mark-length pulses have a start-end and trail-end pulse width of 1T, and even-numbered mark-length pulses have a start-end and trailing-end pulse width of 1.5T. Furthermore, a constant interval of 1T is secured between each pulse. As a result, the interval between the Hi period and the Lo period in the delayed multi-pulse signal 99 can be sufficiently widened, and the laser can be irradiated to the intermediate portion of the recording mark at a substantially uniform density.

【0051】

By the above operation, the optical recording apparatus of the present embodiment irradiates the intermediate portion of the recording mark with a laser at a substantially uniform density, so that a good recording mark having a substantially constant mark width in the intermediate portion of the recording mark can be obtained. Can be formed. Further, even at a high density and a high transfer rate, the mark recording start position and the recording end position should be recorded as the mark and the space corresponding to the desired data while facilitating the mark formation under sufficient cooling conditions. Can be done. Therefore, the mark distortion caused by insufficient cooling and the mark distortion caused by the thermal interference caused by the high density can be reduced, and the jitter of the signal reproduced from the recorded mark of the information layer can be reduced. As a result, it becomes possible to record a signal having a small bit error rate.

【0052】

Further, the method of determining the recording start position and recording end position of the recording mark by delay-controlling the start end pulse position and the rear end pulse position has been described, but the rear edge position of the start end pulse is fixed and the start end pulse start edge position is delayed. Then, the start edge position of the rear end pulse may be fixed and the end edge position of the rear end pulse may be delayed and controlled.

【0053】

[Effect of the invention]

As described above, according to the present invention, it is possible to set the optimum recording conditions when performing high-density mark length recording in an optical recording medium for recording with a short-cycle clock. Therefore, the jitter of the signal that reproduces the recording mark is reduced, and the bit error rate of the signal can be improved. Further, since the recording power level can be compensated, the power control variation between the devices can be reduced. As a result, the data recording rate and the recording density are greatly improved, so that the optical recording medium can be increased in speed and capacity.

[Simple explanation of drawings]

[Figure 1]

Block diagram showing the optical recording device of the present invention [Figure 2]

Cross-sectional view of the optical recording medium of the present invention [Fig. 3]

Timing chart of the optical recording device of the present invention [Fig. 4]

The figure which shows the recording pulse of the optical recording apparatus of this invention. [Fig. 5]

The figure which shows the recording pulse of the optical recording apparatus of this invention. [Fig. 6]

The figure which shows an example of the recording pulse of this invention [Fig. 7]

Timing chart of conventional optical recording device [Fig. 8]

Timing chart of conventional optical recording device [Fig. 9]

Block diagram showing the optical recording device of the present invention [Explanation of symbols]

2 Basic pulse generator 6 Data length detector 22 Timing control unit 29 frequency divider circuit 33 Laser drive circuit 70 Demodulator 201 Optical recording medium 203 Information layer 206 Management area