JP2002334441A - Optical recording method and optical recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical recording method by which multi-level recording can be performed even if variations are present in the state of the recording layer of an optical recording medium. SOLUTION: A plurality of virtual recording cells 40 each of which has a predetermined length are assumed in succession on a recording layer 12 of an optical recording medium 10 on which information can be recorded by irradiation with a laser beam, and multi-level recording is performed by changing over recording intensity which is irradiation time and/or irradiation power of the laser beam to the recording layer, so that five levels or more reflectance values of the virtual recording cells 40 are obtained. In the recording process, test irradiation of the laser beam is carried out preliminarily in three levels of recording intensity, the recording intensity of one selected level is corrected so as to yield the amount of reference reflected light, and the recording intensity of other levels is corrected on the basis of the difference of the adjustment value and the levels. At information recording, the amount of reflected light and the amount of reference reflected light of the virtual recording cell 40 of the selected level are compared, the recording intensity of the selected level is corrected on the basis of the difference, and the recording intensity of other levels is adjusted sequentially on the basis of the difference of the correction value and the level.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention enables multi-level recording of data by irradiating at least one of a laser beam irradiation time and an irradiation power in multiple stages according to data to be recorded. The present invention relates to an optical recording method and an optical recording medium.

[0002]

2. Description of the Related Art In contrast to a conventional optical recording medium, in which data is recorded by changing the length of a reproduction signal (the length of a reflection signal modulation section) in multiple steps, the depth of the reproduction signal (the depth of the reproduction signal) is reduced. Many studies have been made on a method of recording a plurality of data in each signal of the same length by switching the modulation degree of the reflection signal) in multiple stages.

According to this optical recording method, a plurality of data can be recorded in a depth direction as compared with a case where binary data is simply recorded based on the presence or absence of a pit. The amount can be increased, and therefore, the linear recording density can be improved. As a method of switching the depth of the reproduction signal in multiple stages, generally, the power of the laser beam is switched in multiple stages to form some kind of different recording marks. At present, as a recording medium, a recording medium utilizing holography and a recording medium having a multilayer recording layer have been proposed.

[0004] Here, recording each data so that the modulation degree of the reflected signal changes in multiple steps is called multi-level recording.

[0005]

On the other hand, in these multi-level recordings, the signal quality at the time of reproduction deteriorates as the power of the laser beam at the time of recording increases, that is, as the depth of the reflected signal to be formed increases. There was a problem of doing. Although the reason for this has not been clarified, the present inventor's expectation is thought to be that the area of the recording mark (recording mark area) increases due to an increase in the laser power.

For example, when recording marks are shortened in order to increase the amount of information recorded on a recording medium, and multilevel recording is performed by switching the laser power in multiple stages, the signal quality is significantly degraded. In the end, the advantages of multi-level recording could not be exploited. In other words, in order to adopt multi-level recording, the interval between recording marks must be widened so that data detection can be performed to some extent even if signal quality is deteriorated.

Further, under the concept of achieving multi-level recording by switching the laser power stepwise as in the prior art, the recording mark length must be larger than the diameter of the focused beam (beam waist) during recording. Will be. In general, the diameter of a focused beam is represented by Kλ / NA (K: constant, λ: laser wavelength, NA: numerical aperture of a lens). For example, when the optical recording medium is a CD (compact disk),
In the pickup used in this CD, λ = 780n
m and NA = 0.45 are common, and the diameter of the focused beam is about 1.6 μm. In this case, the recording mark length is 1.6
In the vicinity of μm, the above-mentioned problem of signal deterioration becomes apparent,
It was difficult to perform multi-level recording of five or more steps by changing the laser power.

The above problem is considered to be the result of complicated intertwining of all factors such as the power setting of the laser beam and the characteristics of the recording medium. However, as far as the inventor knows, the cause has not been clarified at present. In fact, high-level multi-level recording has not been achieved, including its recording medium and recording method.

The present invention has been made in view of the above problems, and proposes a new multi-level recording method by setting a recording method on a recording medium to a predetermined state. The goal is to achieve a record.

In the multi-level recording, when the recording layer is made of a dye, the state of the recording layer varies due to unevenness in the thickness of the recording layer, and when the recording layer is made of an inorganic material, the state of the recording layer varies. Although the same recording level may not be obtained even by recording, an object of the present invention is to provide an optical recording method and an optical recording medium that suppress this variation and achieve multi-level recording in more stages.

[0011]

Means for Solving the Problems The present inventors have conducted intensive studies on optical recording media, assumed virtual recording cells of a fixed size in the recording layer, and formed recording marks of different sizes here. We have found a multi-step recording method that modulates the reflectivity of the entire virtual recording cell in multiple steps, and show that this recording method enables high-density multi-level recording of five or more steps on an optical recording medium. confirmed.

Further, even when the state of the recording layer varies, the variation width of the amount of light reflection of the recording mark from the virtual recording cell by the laser beam having the same recording intensity is controlled to be within a predetermined value. It was confirmed that multi-level recording of more stages could be performed.

In detail, according to the analysis of the present inventor, in order to properly perform multi-level recording with five or more steps of reflectance fluctuation in a virtual recording cell, the reflectance levels of the signals at each step must be at a certain interval. It was found that, if they did not have the above, the reflectance of each signal would interfere with each other, which would hinder recording and reproduction.

Various studies have been made to perform good recording and reproduction without being affected by such inter-signal interference. In particular, in order to perform multi-level recording in five or more steps, the thickness of the recording layer must be increased. It has been found that it is necessary to suppress the fluctuation width of the size of the recording mark caused by the laser beam having the same recording intensity due to fluctuations such as unevenness of the recording mark.

Therefore, during information recording by the multi-level recording method, a running OPC (Optimun Power) for comparing the amount of light reflected from the virtual recording cell with the reference amount of reflected light and correcting the recording intensity of the laser beam to be appropriate. Contr
ol; recording laser beam intensity optimization).

That is, the above objects can be achieved by the present invention described below.

(1) An optical recording method on an optical recording medium capable of recording information by forming a recording mark by irradiating a laser beam to a recording layer formed on a light transmitting substrate, In the recording mark forming area of the optical recording medium, a plurality of virtual recording cells having a predetermined unit length and a predetermined unit width in a direction perpendicular to the unit length are continuously defined in the direction of relative movement with the laser beam. The amount of light reflected from a virtual recording cell on which a recording mark is formed by laser beam irradiation is modulated in five or more steps in accordance with the size of the recording mark, and the laser beam is applied to the virtual recording cell. When irradiating a laser beam by switching the recording intensity, which is at least one of the irradiation time and the irradiation power, to five or more steps, at least one obtained from the optical recording medium While checking the amount of light reflected stage, optical recording method, which comprises a multi-level recording write strength while correcting corresponding to the reflection light amount of the at least one stage.

(2) The optical recording method according to (1), wherein the confirmed amount of reflected light is compared with information on a laser beam recording intensity recorded at the time of recording.

(3) The optical recording method according to (1) or (2), wherein the information on the recording intensity of the laser beam at the time of recording is recorded in a wobble or a land prepit.

(4) The optical recording method according to (1), wherein the amount of reflected light in at least one step is confirmed, and the amount of reflected light before and after the step is also confirmed.

(5) The optical recording method according to (1), wherein the amount of reflected light is confirmed by using a virtual recording cell in a predetermined portion of the recording medium.

(6) The laser beam recording intensity at the time of recording is kept constant from the time when the laser beam recording intensity at the time of recording is corrected until the amount of reflected light to be confirmed deviates by a predetermined amount (1). Optical recording method.

(7) An optical recording method on an optical recording medium capable of recording information by irradiating a laser beam to a recording layer formed on a light transmitting substrate to record information. In the recording mark forming area of the optical recording medium, a plurality of virtual recording cells having a predetermined unit length and a predetermined unit width in a direction perpendicular to the unit length are continuously defined in the direction of relative movement with the laser beam. Before switching the recording intensity, which is at least one of the irradiation time and the irradiation power of the laser beam, to the virtual recording cell in five or more steps, and before irradiating the laser beam, at least one of the recording intensities of the steps A recording mark is formed by irradiating a laser beam to a part of the virtual recording cell at a recording intensity of, and the amount of reflected light obtained from the virtual recording cell is determined in advance. Optical recording method, characterized by multi-level recording while correcting a laser beam recording intensity by comparing the the amount of light reflected on the recording marks of the reference virtual recording cell.

(8) In the above (1) or (7), the information relating to the recording intensity of the laser beam at the time of recording is recorded in a lead-in area, a wobble, or a land pre-pit. Optical recording method.

(9) In the above (7), the amount of reflected light from the virtual recording cell in at least one stage is confirmed, and the difference between the amount of reflected light and the amount of reflected light from the virtual recording cell before and after this stage is determined. An optical recording method characterized in that the laser beam recording intensity is corrected after confirming the recording.

(10) An optical recording medium capable of recording information by forming a recording mark by irradiating a recording layer formed on a light transmitting substrate with a laser beam,
In the recording mark forming area, a plurality of virtual recording cells having a predetermined unit length and a predetermined unit width in a direction perpendicular to the unit length are continuously defined in the direction of relative movement with the laser beam, and the laser beam By switching the recording intensity, which is at least one of the irradiation time and the irradiation power, to five or more levels and irradiating the laser beam, the amount of light reflected from the virtual recording cell on which the recording mark is formed depends on the size of the recording mark. So that it can be modulated in five or more stages,
An optical recording medium having information serving as a reference for correcting the laser beam recording intensity used for recording when recording is performed by switching the recording intensity of the laser beam to five or more levels.

[0027]

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

An optical recording medium (disc) 10 according to an embodiment of the present invention has a CD-R using a dye for the recording layer 12.
(Write-once compact disc), a substrate 14 made of a transparent substrate, and a laser beam guide spirally or concentrically formed on one surface (the upper surface in FIG. 1) of the substrate 14 around the center of the disk. The recording layer 12 made of a dye applied to cover the groove 16, a reflective film 18 of gold or silver formed on the recording layer 12 by sputtering or the like, and a protective layer covering the outside of the reflective film 18 20 are formed.

The dyes used in the recording layer 12 are organic dyes such as cyanine, merocyanine, methine dyes and derivatives thereof, benzenethiol metal complexes, phthalocyanine dyes, naphthalocyanine dyes, and azo dyes.

The multi-level recording on the optical recording medium 10 is executed by the optical recording device 30 shown in FIG.

The optical recording apparatus 30 is a CD-R recorder, and drives the optical recording medium (disk) 10 to rotate at a constant linear velocity by a spindle motor 32 via a spindle servo 31. This records information on the optical recording medium (disc) 10.

The laser 36 is controlled by a control device 50 via a laser driver 38 in accordance with information to be recorded.
The laser beam irradiation time per 0, eg, the number of laser pulses, and / or the irradiation power, eg, pulse height, is controlled.

Reference numeral 42 in FIG. 2 denotes a recording optical system including an objective lens 42A, a half mirror 42B, and a photodetector 42D. The objective lens 42 </ b> A uses the focus tracking servo 44 to
The focus tracking is controlled so that the light is focused on the recording layer 12. Also, the objective lens 42A and the half mirror 42
B is controlled by the feed servo 46 from the inner peripheral side to the outer peripheral side at a predetermined speed in synchronization with the rotation of the disk 10. The photodetector 42D is a half mirror 4
The light reflected by 2B is received, converted into an electric signal, and output to control device 50.

The spindle servo 31, laser driver 38, focus tracking servo 44, and feed servo 46 are controlled by a controller 50. Recording layer 1
The data (information) to be recorded in 2 is input to the control device 50.

When the irradiation power of the laser beam is modulated, an optical modulator 41 is arranged on the optical path of the laser beam as shown by a two-dot chain line in FIG. 2 in addition to the pulse height control described above. Then, means for controlling this by the control device 50 may be used.

Next, the virtual recording cell 40 and recording marks recorded in the virtual recording cell 40 will be described.

As shown in FIG. 1, the virtual recording cell 40 is continuously defined in the groove 16 in the rotation direction of the disk 34, that is, the circumferential direction S. As shown in FIG. 3, the length H of each virtual recording cell 40 in the circumferential direction S is set to a length shorter than the beam diameter (diameter of the beam waist) D. Is irradiated, recording marks 48A to 48G schematically illustrated are formed in accordance with information to be recorded.

More specifically, recording marks 48A to 48G having different diameters are formed at the center of the laser beam by appropriately changing the laser irradiation time of the laser beam emitted from the laser 36 (the laser beam is formed by a laser beam). Since the laser beam is irradiated while rotating the disk 10, the recording mark has an elliptical length corresponding to the irradiation time, and the width of the recording mark depends on the irradiation time and the irradiation power. growing).

This is because the focused laser beam generally has a Gaussian distribution,
In the above, recording is performed only in a portion where the irradiation energy of the laser beam exceeds a certain threshold value. Therefore, by changing the irradiation time and / or the irradiation power of the laser beam, the spot of the laser beam that can be recorded on the recording layer 12 is changed. It is considered that the size changes. This allows
For example, a seven-step recording mark 48A as shown in FIG.
~ 48G can be formed.

In this case, the size (area) of each of the recording marks 48A to 48G is set so that the light reflectance of the reflected light when the read laser beam is irradiated to the virtual recording cell 40 becomes seven levels. The light reflectance increases as the size of the recording mark decreases, and reaches a maximum reflectance in a virtual recording cell where no recording mark is formed, and a minimum reflectance in a virtual recording cell where the maximum recording mark 48G is formed. More specifically, the light reflectivity is measured for each of the recording marks 48A to 48A.
The setting is made in consideration of the area ratio of the G to the virtual recording cell 40 and the light transmittance of the recording mark itself.

The light transmittance of the recording marks 48A to 48G itself may be changed when the material constituting the recording layer 12 is decomposed and deteriorated by the irradiation of the laser beam and the refractive index changes, or when the thickness direction of the recording layer 12 changes. Depends on quantity. If the light transmittance of the formed recording mark portion is zero, this need not be considered.

Next, an OPC and a running OPC for performing correction to make the recording intensity of the laser beam proper when recording information on the disk 10 will be described with reference to FIG.

Here, it is assumed that the recording intensity of the laser beam is controlled by the density of the laser pulse applied to one virtual recording cell 40, that is, by the irradiation time of the laser beam.

First, in step 101, the second, fourth and sixth recording intensities of the seven levels of recording intensities, ie, the test virtual recording cells (not shown) in the test area of the disk 10, ie, The recording marks 48B, 48
By irradiating a laser beam with a recording intensity corresponding to D and 48F, test recording marks having three different sizes are formed.

Then, the process proceeds to a step 102, wherein the photodetector 42D detects a test reflected light amount of each test virtual recording cell on which the test recording mark is formed, and outputs the detected value to the control device 50.

In the next step 103, the control device 50 sets the three types of the test reflected light amounts
The test reflected light amount corresponding to the intermediate recording mark 48D is set as the test reflected light amount in the selection step, and the laser driver 38 is set in the control device 50 in advance so as to correspond to the recording intensity in the selection step. The reference reflected light amount is compared with the test reflected light amount in the selection step, and in step 104, the control device 50 is controlled so that the reflected light amount in the selected step becomes the reference reflected light amount in accordance with the result of the comparison.
The recording intensity at is corrected.

In the next step 105, the other two levels of recording are performed such that the difference between the test reflected light quantity and the reference reflected light quantity corresponding to the other two levels of recording intensity is a difference corresponding to the step difference. Correct the intensity.

At step 106, information recording is started. Thereafter, at step 107, the amount of reflected light from the virtual recording cell on which the recording mark is formed by the laser beam irradiation of the recording intensity at the selection stage is changed as necessary. In step 108, the detected value is compared with the set reference reflected light amount.

In step 109, the recording intensity in the selection stage is corrected based on the difference between the two so that the amount of reflected light matches the reference amount of reflected light. In step 110, the recording intensity in the other two stages is also corrected. The correction is made in the same manner, and in step 111, the remaining recording marks 48A, 48
Multilevel recording is performed while correcting the recording intensities corresponding to C, 48E, and 48G based on the three levels of corrected recording intensities according to the step difference (for one step).

Further, the recording intensity of the laser beam at the time of recording may be constant from the time of correction until the amount of reflected light deviates by a predetermined amount.

As a result, even if the state of the recording layer 12 of the disk 10 changes, in the case of multi-level recording of five or more stages as described above, the difference between the recording stages, that is, the reflection of the virtual recording cell 40 It is possible to distinguish the absolute value difference of each stage of the rate.

In the example of the above embodiment, the test reflected light amount in the middle selection stage is used as a reference from the test reflected light amounts in the three stages. However, the present invention is not limited to this. The test reflected light amount may be used as a reference. However, when the test reflected light amount at the intermediate stage is used as a reference, the adjustment is easier. Further, the test reflected light amount may be four or more levels.

Further, in the above invention, it is preferable that the recording layer of the optical recording medium contains an organic dye component. Actually, as described in the examples described later, the above-described multi-level recording is achieved by a method of generating a recording mark by a reaction of an organic dye component.

In the example of the present embodiment, the optical recording medium 10 is configured as a CD-R disk as described above. However, the present invention is not limited to this. It is generally applied to an optical recording medium, and is not limited to a disk-shaped rotating body.

In the above embodiment, the recording layer 12 uses an organic dye such as cyanine. However, the present invention is not limited to this. It suffices if the material satisfies the characteristic of dispersion of the reflectance. An organic dye or an inorganic material other than those described above may be used, or another material may be used as appropriate. However, when the organic dye as described above is used, it is possible to reliably change the size of the recording mark in accordance with the irradiation time of five or more steps of the laser beam and to perform recording with extremely high accuracy. Was.

Further, in the above embodiment, the optical recording medium 1 includes an unrecorded area in which information such as data is not recorded.
However, the present invention is not limited to this, and is also applicable to an optical recording medium in which information is recorded in multi-levels in five or more steps.

Furthermore, the size of the virtual recording cell 40 set on the recording layer 12 when forming a recording mark by the optical recording device 30 is not limited to the embodiment. On the other hand, when recording marks are recorded in further multiple steps such as eight steps, the recording mark may be set to be equal to or larger than the laser beam waist. In that case, some of the recording marks can be made larger than the beam waist. Further, the present invention is applicable to an optical recording medium having no groove 16.

The recording laser beam is applied to the recording layer 1.
The shape of the recording medium 10 is changed by adding a beam shaping prism 42C or an aperture (not shown) to the objective lens 42A, for example, as shown in FIG. May be formed in an oval or linear shape that is short in the feeding direction and long in the direction perpendicular to the feeding direction. In this case, since the recording mark 49 is shortened, the virtual recording cell can be further shortened. That is, the recording density can be improved.

Further, in the optical recording medium 10, as shown by reference numeral 52 in FIG. 1, a plurality of pits having different reflectivities may be provided in advance in accordance with the number of signal modulation stages. A part of the optical recording medium,
For example, multilevel recording may be performed in advance in the lead-in area as described above. The plurality of pits 52 and / or the recording mark 54 of the multi-level recorded portion include information for individually identifying the recording medium, information for identifying the optical recording medium for multi-level recording, and information for identifying the recording medium. Specific information such as information for determining a recommended recording power of a laser beam for recording and reproduction may be recorded. The specific information is read at the time of reproduction and / or recording of the optical recording medium, thereby reliably identifying the optical recording medium for multi-level recording, further identifying them individually, or recording them in advance. The irradiation time of the laser beam can be determined according to the number of pit stages, and more reliable multi-level recording / reproduction can be performed.

Normally, a CD-R / RW or DVD-R / RW
The medium for recording contains signals by making the recording groove meander (wobble). This signal is called an address signal, and the recording apparatus can move the recording head to a predetermined position by reading this signal.

For example, in the case of a CD-R / RW, a time code of minutes and seconds in which the position is replaced with time is recorded in this address signal. The recording device reads the time code, moves the head to the lead-in portion, and can read various data.

The multi-level optical recording medium of the present invention
When used (recording / reproducing) in a recording apparatus applied to DR / RW, an address signal based on wobble can be employed. However, a signal system such as an address code which is different from a normal CD-R / RW time code is adopted. In a normal recording device, an address signal different from that of a CD-R / RW cannot be read, and the head cannot be moved to a predetermined position (in this case, the multi-level recording optical medium is ejected from the recording device).

On the other hand, in a recording apparatus supporting multi-level recording, if the special address is set to be recognizable, the head can be moved to the lead-in portion to read a signal.

That is, the multi-level optical recording medium can be distinguished from other optical recording media by adopting an address different from usual.

The recording using the wobble is performed, for example, by modulating the wobble of the grooves 104A to 104C in the lead-in area 102 of the optical recording medium 10 as shown in FIG. 1 or the wobble 56B shown in FIG. .

Specifically, as shown in FIG. 8, each groove 104 is not changed without changing the wobble amplitude Wb.
A, 104B, 104C wobble periods T _A , T _B , T _C
change. For example, the user area 10 shown in FIG.
6, the wobble period T _O of the groove 16 is set as the basic period, the longer wobble period T _B is “1”, and the shorter wobble periods T _A and T _C are “0” on a binary signal.
The above various information is recorded. Therefore, for example, when the wobble period is “0”, “1”, or “0” from the inner peripheral side of the optical recording medium as described above,
Is for multi-level recording.

Further, the predetermined information as described above is
As the recording start position information, the recording is started from a predetermined position in the user area 106 based on the information. This is also information on the start position of the virtual recording cell 40.

As another example of a recording method of the above-mentioned various information, as shown in FIG. 9, the above-mentioned various information is put on land pre-pits 17A formed on the lands 17 between the grooves 16 as shown in FIG. For example, when the period between the land pre-pits is short, binary recording is performed as "1", and when the period is long, "0" is recorded.

As still another example, as shown by reference numeral 56A (groove interruption portion) in FIG. 10 or FIG. 1, the groove 16 is interrupted, and the length of the interrupted groove, for example, "1" when short, If it is long, it indicates "0".

The information recorded by the information recording means shown in FIGS. 7, 9 and 10 can be read by a conventional binary recording type reproducing apparatus. Even if it is loaded in a binary recording type reproducing and / or recording device by mistake, it is easily found that this is a multi-level type.

Further, the various information described above is, for example, shown in FIG.
As shown in (1), multi-level recording can be performed in the lead-in area 102 in advance. In this case, FIG.
, The recording marks of the first five virtual recording cells 401 to 405 indicate that the medium is a multi-level recording medium, the number of stages of multi-level recording, the next five virtual recording cells 4
It is possible to record the recommended laser power for recording or reproduction by using the recording marks 06 to 410, for example. These methods can be used alone or in combination.

[0072]

EXAMPLES Examples of the present invention will be described below together with comparative examples.
The specific conditions in this example and comparative example are as follows.

A multi-level recording experiment was performed using a CD-R using a dye for the recording layer as the recording medium 10, and
FIG. 5 shows the result of calculating the DR.

The measurement position was in the range from the inner circumference to the middle and outer circumferences of the disk, and the radius was between 20 mm and 60 mm.

The SDR mentioned here is a signal variation at each stage obtained from the reflectance and the dynamic range at each stage of the multi-level. (The standard deviation σ of the reflectance is normalized by the dynamic range (no
It is needless to say that if this variation is small, a good signal can be recorded and reproduced. According to experiments by the present inventors, the SDR value is preferably 5% or less, more preferably 3% or less. Here, the target was 2% or less.

The recording / reproducing apparatus used was a modified general-purpose drive for CD-R / RW, and the dynamic range was measured by the reflectance measured using a digital oscilloscope manufactured by Hewlett-Packard Company.

As can be seen from FIG. 5, since the optimum power at the start of recording is determined by OPC, if this is not done, the SDR value is poor from the beginning, and if running OPC is not performed, the degree of deterioration will increase (see FIG. 5). 5 D).

If the OPC is not performed and the running OPC is not performed, the optimum power shifts to a higher or lower direction, and if the optimum power shifts to a higher one (see FIG. 5B), the recording state is advanced more than expected, and the SDR is increased. Becomes worse, but from a certain point, the recording layer burns out,
After that, the SDR does not seem to get worse.

Conversely, when the recording state shifts to a smaller one (see FIG. 5C), the state in which the recording state does not progress to the target state becomes worse, and the SDR continues to deteriorate.

As shown in FIG. 5A, in the multi-level recording of the present invention in which OPC and running OPC were performed, a good SDR value of 2% or less could be obtained.

[0081]

According to the optical recording method of the present invention, at the time of new multi-level recording of five or more steps, even if the state of the recording layer varies, recording at each step can be distinguished. Therefore, more multi-level recording can be performed.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional perspective view showing a main part of an optical recording medium used in an optical recording method according to an embodiment of the present invention.

FIG. 2 is a block diagram showing an optical recording apparatus for recording information on the optical recording medium using a laser beam and performing the optical recording method of the present invention.

FIG. 3 is a schematic diagram showing a relationship between the recording mark, a virtual recording cell and its light reflectance when a recording mark is formed on a recording layer using the optical recording medium.

FIG. 4 is a flowchart showing the optical recording method.

FIG. 5 is a schematic perspective view showing a case where a laser beam for irradiating a virtual recording cell has another shape.

FIG. 6 is a diagram showing a comparison between measurement results of an example of the present invention and a comparative example

FIG. 7 is an enlarged schematic view showing a wobble in which various information is recorded in advance on the optical recording medium of the present invention.

FIG. 8 is a diagram showing a relationship between a wobble cycle of the wobble and a binary signal;

FIG. 9 is a schematic diagram showing a relationship between a land prepit on which various information is recorded and a binary signal in the optical recording medium of the present invention.

FIG. 10 is a schematic diagram showing a relationship between a length of a groove interrupted by recording various information in the optical recording medium of the present invention and a binary signal.

FIG. 11 is a schematic diagram showing virtual recording cells and recording marks on which various information is recorded in the optical recording medium of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Optical recording medium 12 ... Recording layer 14 ... Substrate 16, 104A-104C ... Groove 18 ... Reflection film 20 ... Protective layer 30 ... Optical recording device 32 ... Spindle 36 ... Laser 38 ... Laser driver 40, 401-410 ... Virtual recording Cell 42: Recording optical system 42A ... Objective lens 42B ... Half mirror 42C ... Beam shaping prism 42D ... Photodetector 44 ... Focus servo circuit 46 ... Feed servo circuit 48A to 48G, 49, 54 ... Recording mark 50 ... Control device 52 ... Bit 56A … Groove break 56B… wobble D… beam

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Takashi Doi Inventor, TDK Corporation, 1-13-1 Nihonbashi, Chuo-ku, Tokyo (72) Inventor Shiro Inventor Shiro 13-1 Nihonbashi, Chuo-ku, Tokyo Incorporated F term (reference) 5D029 JA04 JB11 JC02 5D090 AA01 BB03 BB04 CC01 DD03 DD05 KK03 5D119 AA22 AA23 BA01 BB02 BB04 DA01 EB04 FA05 HA16 HA19 HA20 HA28 HA48 HA59 JA07

Claims (10)

[Claims] An optical recording method on an optical recording medium capable of recording information by forming a recording mark by irradiating a recording layer formed on a light transmitting substrate with a laser beam, the method comprising: In the recording mark forming area in the optical recording medium, a plurality of virtual recording cells of a predetermined unit length and a predetermined unit width in a direction perpendicular to the unit length are continuously defined in the direction of relative movement with the laser beam, The amount of reflected light from the virtual recording cell on which the recording mark is formed by laser beam irradiation is modulated in five or more stages in accordance with the size of the recording mark. When switching the recording intensity, which is at least one of the irradiation time and the irradiation power, to five or more steps and irradiating the laser beam, at least one step obtained from the optical recording medium is used. While checking the amount of reflected light, optical recording method, which comprises a multi-level recording write strength while correcting corresponding to the reflection light amount of the at least one stage. 2. The method according to claim 1, wherein:
An optical recording method comprising comparing information on laser beam recording intensity at the time of recording which has been recorded in advance. 3. The optical recording method according to claim 1, wherein the information on the recording intensity of the laser beam recorded in advance is recorded in a wobble or a land prepit. 4. The optical recording method according to claim 1, wherein the amount of reflected light in at least one step is confirmed, and the amount of reflected light before and after the step is also confirmed. 5. The optical recording method according to claim 1, wherein the amount of reflected light is confirmed by using a virtual recording cell of a predetermined portion of the recording medium. 6. The method according to claim 1, wherein the recording intensity of the laser beam at the time of recording is kept constant from the time when the recording intensity of the laser beam at the time of recording is corrected until the amount of reflected light to be confirmed deviates by a predetermined amount. Optical recording method. 7. An optical recording method on an optical recording medium capable of recording information by irradiating a laser beam to a recording layer formed on a light-transmitting substrate to form a recording mark, wherein: In the recording mark forming area in the optical recording medium, a plurality of virtual recording cells of a predetermined unit length and a predetermined unit width in a direction perpendicular to the unit length are continuously defined in the direction of relative movement with the laser beam, Before switching the recording intensity, which is at least one of the irradiation time and the irradiation power of the laser beam, to the virtual recording cell in five or more stages and irradiating the laser beam, at least one of the recording intensities of the stages is performed. At the recording intensity, a recording mark is formed by irradiating a part of the virtual recording cell with a laser beam, and the amount of reflected light obtained from the virtual recording cell is determined in advance. An optical recording method, wherein multi-level recording is performed while correcting the recording intensity of a laser beam by comparing the amount of reflected light on a recording mark of a reference virtual recording cell. 8. An optical recording method according to claim 1, wherein the information on the recording intensity of the laser beam at the time of recording is recorded in a lead-in area, a wobble, or a land prepit. . 9. The method according to claim 7, wherein the amount of reflected light from the virtual recording cell in at least one stage is confirmed, and a difference between the amount of reflected light and the amount of reflected light from the virtual recording cell before and after the stage is also confirmed. And an optical recording method for correcting the recording intensity of the laser beam. 10. An optical recording medium capable of recording information by forming a recording mark by irradiating a recording layer formed on a light-transmitting substrate with a laser beam, wherein the recording mark forming area includes: In the direction of relative movement with respect to the laser beam, a plurality of virtual recording cells having a predetermined unit length and a predetermined unit width in a direction perpendicular to the predetermined length are continuously defined, and the irradiation time and irradiation power of the laser beam are defined. By irradiating a laser beam while switching the recording intensity, which is at least one of the above, to five or more steps, the amount of reflected light from the virtual recording cell on which the recording mark is formed is modulated to five or more steps according to the size of the recording mark. So that
An optical recording medium having information serving as a reference for correcting the laser beam recording intensity used for recording when recording is performed by switching the recording intensity of the laser beam to five or more levels.