JP3936953B2 - Dye-type recordable DVD medium recording / reproducing method and apparatus - Google Patents

Description

  The present invention is a dye-based write-once DVD that can record and reproduce information by irradiating a light beam to cause optical changes such as transmittance and reflectivity in a recording layer, and can additionally write information. The present invention relates to a medium recording / reproducing method and apparatus.

Currently, DVD ± R is being developed as a large-capacity optical disk. As elemental technologies for improving the recording capacity, it is necessary to develop recording materials for recording pit miniaturization, use of image compression technology represented by MPEG2, shortening the wavelength of semiconductor laser for reading recording pits, etc. .
Until now, only 670 nm AlGaInP laser diodes for bar code readers and measuring instruments have been commercialized as semiconductor lasers in the red wavelength range. Began to use in the optical storage market. In the case of a DVD drive, it is standardized by using a laser diode of two wavelength bands of 635 nm band and 650 nm band as a light source. On the other hand, a read-only DVD-ROM drive is commercialized at a wavelength of about 650 nm.

In general, a dye-based recordable DVD medium in which pits (marks) are formed by a heat mode is optimized for the pulse width and recording power of a recording pulse train generated by laser emission during recording at a specific recording speed. The state of marks and spaces formed changes with speed. That is, there is a shortage of heat capacity due to the leading heating pulse necessary for forming the mark, the heating temperature that reaches the optimum decomposition temperature differs, the average length of the mark varies, and the duty ratio of the optimum heating pulse differs As a result, a uniform mark width cannot be obtained, and thickening and thinning occur depending on the mark length, so that the jitter characteristics deteriorate.
Therefore, an optical recording medium that supports recording from low linear velocity to high linear velocity is recorded by encoding in advance a stamper from the optimum recording condition at the lowest linear velocity to the optimum recording condition at the highest linear velocity. By using a substrate transferred from the stamper, the recording at each linear speed is optimized.

However, as the speed increases, the rotation at the innermost circumference is considerably faster particularly in CLV recording, and therefore there is a case where the rotation at the highest linear velocity is impossible from the innermost circumference to a certain radius position. Therefore, recording is started at the rotation speed that can be rotated on the innermost circumference, and the recording speed is switched to the maximum linear speed when recording is performed up to a radial position where recording can be performed at the maximum linear speed. If the recording linear velocity is switched, the recording strategy and recording power are naturally different from the parameters used from the innermost circumference, so that recording is performed under the optimum conditions at the highest linear velocity. However, although the recording strategy can use parameters coded on the medium, the recording power often deviates from the optimum recording power coded according to the recording environment at that time. For example, the internal temperature of the writing drive rises from the beginning of writing after continuous recording for a certain time due to heat generated by the rotary motor, heat generated by the LD itself, and the like. When the internal temperature rises, the LD becomes longer in wavelength. In particular, the sensitivity of the dye-based recording medium is wavelength-dependent, so the influence is large, and a deviation from the encoded optimum recording power is likely to occur. When the optimum recording power is deviated by increasing the wavelength of the LD, the optimum value is almost deviated.
In addition, trial writing for optimizing the recording power at the linear velocity switching position cannot be employed because of the continuity of data and the reduction in data capacity.
Needless to say, when recording at a constant linear speed without switching the recording linear speed, power optimization is performed using the innermost power calibration area (power measurement area) and recording is started. Yes.

On the other hand, with the recent increase in the data writing speed to the optical disk, during the writing of data to the optical disk, the transfer of the writing data transferred from the host computer or the like rather than the data writing speed to the optical disk. The speed may be slow. In this way, a state where there is no data to be written is called a buffer underrun.
Therefore, in recent optical disk apparatuses, recording protection means called by names such as so-called burn proof and just link are often provided so as not to waste the optical disk due to the occurrence of buffer underrun. According to such a recording protection means, when a buffer underrun occurs, the writing is interrupted and the apparatus waits for a while. When the data transfer speed becomes faster after the interruption, or when data to be sufficiently written is accumulated in the buffer memory, the interruption is canceled and the writing is performed again.
By providing such a recording protection means, it is possible to prevent the optical disc from being wasted even if a buffer underrun occurs.
However, when recording protection is adopted, in order to resume data writing, the rotation of the optical disk and the timing of data writing must be synchronized before resuming writing so that data writing can be restarted from the interrupted address. It is necessary to keep. Specifically, the position of the optical pickup is returned before the interrupted address, and the data that has been written so far is read out at the same speed as that written so far to obtain the EFM signal. On the other hand, an EFM signal for writing data is generated inside the encoder, and the two signals are combined to synchronize.

  Known examples of optical recording media using a dye in the recording layer include polymethine dyes or those using a polymethine dye and a light stabilizer as a recording material, tetraazaporphyrin (porphyrazine) dye or cyanine dye + azo metal chelate. A layer composed of a dye (salt-forming dye) and a reflective layer as a recording layer, a formazan (metal chelate) dye + other dye as a recording material, a dipyrromethene (metal chelate) dye + other dye as a recording material There are things to use and there is no time for enumeration. Many recording materials that use dyes for multi-pulse recording are also known. However, as far as the present inventors know, the recording speed of a dye-based recordable DVD medium such as the present invention is set to the maximum linear speed. There are no literatures that focus on the power control method for switching when switching and the recording waveform when performing high linear velocity recording.

An object of the present invention is to provide a recording / reproducing method and apparatus capable of obtaining a good recording waveform when performing high linear velocity recording on a dye-based recordable DVD medium. In particular, an object is to provide a simple power control method for connection when the recording speed of a write-once type DVD medium corresponding to a high linear velocity is switched to the maximum linear velocity.
Further, the present invention is a new format system for a write-once DVD system using a semiconductor laser having an oscillation wavelength shorter than that of a CD-based medium. In the same manner as the LPP (land prepit) system, Effective method to eliminate unrecorded area, and moreover, data error due to fine cut width control and leakage of LPP signal to the data part at the time of stamper production does not occur compared with DVD-R land pre-pit method The purpose is to provide an excellent method.

The above problems are solved by the following inventions 1) to 11) (hereinafter referred to as the present inventions 1 to 11).
1) On a disc-shaped substrate having a guide groove provided with wobbles, a recording layer mainly composed of an organic dye is provided, and CLV lines other than the maximum linear velocity recording condition and the maximum linear velocity are provided at predetermined positions on the substrate. When recording / playback on write-once type DVD media with prerecorded high-speed recording conditions, recording can be started on the innermost circumference under CLV linear speed conditions other than the maximum linear speed, and rotation at the maximum linear speed is possible. When switching from the radial position to become the recording at the highest linear velocity, the optimum recording power Po at the highest linear velocity, which was optimized by performing test writing once in the outermost power calibration area, is coded in advance on the substrate. The optimum recording power Pi at the highest linear velocity recorded in the above is compared. If Po> Pi, the recording power obtained by the formula “(Po + Pi) / 2 + (Po−Pi) ² / Pi” is the highest. Starting recording at linear speed In the case of Po ≦ Pi, Pi is set as the recording start recording power at the maximum linear velocity, and the shortest mark is always recorded with one pulse light of the power W0, and the second shortest mark is the power W0. Alternatively, recording is performed with one pulse light whose power is lower than W0 or power W2 lower than W1 and whose pulse front end and / or rear end is increased in power W0 or W1 for a certain period of time. The third and subsequent marks from the side are recorded with one pulsed light whose output is increased to a power W0 or W1 for a certain period of time based on the power W2, and at the time of mark recording. A recording / reproducing method characterized by irradiating a cooling pulse after the rear end of the above-mentioned mark of the mark and setting the amount of irradiation light to 0.1 mW or less for a predetermined time.
2) The recording / reproducing method according to 1), wherein the irradiation time of the cooling pulse after the rear end of the pulse is set to 1/6 to 6/6 of the shortest long space.
3) The heating pulse width of the recording pulse that forms the mark having the shortest space length immediately before is distinguished by whether or not the mark length is the shortest length, and the heating pulse width of the shortest mark is the shortest length. The heating pulse width of the recording pulse that is set longer than the heating pulse width of the non-mark and forms the shortest length mark is distinguished by whether or not the space length immediately before the shortest length mark is the shortest length. The recording / reproducing method according to 1) or 2), wherein the heating pulse width of the mark having the shortest space length is set shorter than the heating pulse width of the mark having the shortest space length.
4) The recording / reproducing method according to any one of 1) to 3), wherein the wobble has a frequency corresponding to 4T to 96T, where T is a basic clock period.
5) The recording / reproducing method according to any one of 1) to 4), wherein the wavelength of the recording light is 600 to 720 nm.
6) The recording layer single layer has a refractive index n of 1.5 ≦ n ≦ 3.0 and an extinction coefficient k of 0.02 ≦ with respect to light in the wavelength range of the recording light and reproducing light wavelength ± 5 nm. The recording / reproducing method according to any one of 1) to 5), wherein k ≦ 0.2.
7) The write-once DVD medium has at least one layer selected from a reflective layer, a protective layer, an adhesive layer, a protective substrate, and a substrate surface hard coat layer as a constituent layer other than the recording layer on the substrate. The recording / reproducing method according to any one of 1) to 6).
8) At least one substrate is provided with an adhesive layer between the two substrates having a guide groove in which wobbles are provided to form a double-sided recording medium, and is used for the adhesive layer 7. The recording / reproducing method according to 7), wherein the adhesive is an ultraviolet curable resin.
9) A dye-based recordable DVD medium having a wobble in the guide groove of the substrate, in which CLV maximum linear velocity recording conditions and CLV linear velocity recording conditions other than the maximum linear velocity are pre-coded and recorded at predetermined positions. In recording and playback, at the innermost circumference, when recording is started under the CLV linear speed conditions other than the maximum linear speed and switching from the radial position where rotation at the maximum linear speed is possible to the recording at the maximum linear speed, The optimum recording power Po at the highest linear velocity optimized by performing trial writing in the outermost power calibration area is compared with the optimum recording power Pi at the highest linear velocity that has been coded and recorded in advance on the medium. , Po> Pi, the recording power obtained by the equation “(Po + Pi) / 2 + (Po−Pi) ² / Pi” is the recording start recording power at the highest linear velocity, and when Po ≦ Pi, Pi recording at maximum linear speed The recording power is used, and the shortest mark is always recorded with one pulse light of power W0, and the second shortest mark is based on power W0, power W1 lower than W0, or power W2 lower than W1. The pulse front end and / or rear end is recorded with one pulsed light whose output is increased to a power W0 or W1 for a predetermined time, and the third and subsequent marks from the shortest are based on the power W2 and the pulse front end and / or Alternatively, the rear end portion is recorded with one pulse light whose power is increased to a power W0 or W1 for a predetermined time, and at the time of mark recording, a cooling pulse is irradiated after the rear end portion of the pulse of all the marks, and the irradiation is performed. A recording / reproducing apparatus characterized by having a function of reducing the amount of light to 0.1 mW or less for a predetermined time.
10) The recording / reproducing apparatus according to 9), which has a function of setting the irradiation time of the cooling pulse after the rear end of the pulse to 1/6 to 6/6 of the shortest long space.
11) The heating pulse width of a recording pulse for forming a mark having the shortest space length immediately before is distinguished by whether or not the mark length is the shortest length, and the heating pulse width of the shortest mark is shortest. The heating pulse width of the recording pulse that is set longer than the heating pulse width of the non-mark and forms the shortest length mark is distinguished by whether or not the space length immediately before the shortest length mark is the shortest length. The recording / reproducing apparatus according to 9) or 10), which has a function of setting a heating pulse width of a mark having a shortest space length shorter than a heating pulse width of a mark having a shortest space length.

Hereinafter, the present invention will be described in detail.
As described above, the optimum recording power Pi at the highest linear velocity recorded and coded on the substrate and the optimum linear velocity optimized by performing test writing in the outermost power calibration area when the linear velocity is switched. There is often a deviation from the optimum recording power Po. Actually, in most cases, the internal temperature of the writing drive rises, and the wavelength becomes longer due to the characteristics of the LD. On the other hand, since the dye-based medium has absorption near the recording wavelength, the optimum recording power increases especially when the recording wavelength is increased. That is, the relationship is Po> Pi.
Therefore, as in the present invention 1, the recording power obtained by the expression “(Po + Pi) / 2 + (Po−Pi) ² / Pi” is used as the recording start recording power at the time of switching the linear velocity, and thereafter the running OPC (optimum power) If the recording power is optimized in (control), the recording quality at the maximum recording linear velocity, which is the object of the present invention, can be kept good.
In addition, when Po ≦ Pi, this is a very rare case, and the difference in power between Po and Pi is small, so if recording is started with the power Pi coded and recorded in advance on the substrate, the recording quality will be improved. Can keep good.

Here, the reason why the recording power obtained by the equation “(Po + Pi) / 2 + (Po−Pi) ² / Pi” when Po> Pi is set to the highest linear velocity recording start recording power will be described.
One item in the formula is simply the average value of Po and Pi, but the two items are terms normalized by the power recorded by encoding the square of the power difference, and this is added to the average value. This is the optimum recording power. In general, a disk-shaped optical recording medium often has inferior mechanical properties on the outer periphery compared to the inner periphery and the middle periphery, and often requires higher recording power than the inner periphery and the middle periphery. Therefore, if the recording power obtained at the outermost circumference is adopted as it is at the middle circumference, there is a high probability that recording will start with an overpowering tendency, while under the mere average value of Po and Pi, there is a possibility of underpower. Therefore, by adding two items to the average value as in the above equation, it is possible to achieve optimum recording power at the time of switching the recording linear velocity.

The basic optimum pulse irradiation pattern is as follows.
Since the shortest mark is difficult to form pits in high linear velocity recording, the light quantity of the recording pulse must always be the highest power, and the pulse power of the shortest mark is set to W0. The base power (power without addition) is W2, and the power added to W2 is W1, and the range of W0 / W1 = 1.01 to 2.00 is preferable, and the range of 1.02 to 1.50 is more preferable. On the other hand, W1 / W2 is preferably in the range of 1.05 to 3.00, more preferably in the range of 1.08 to 2.00.
For the marks other than the shortest length mark, the length of the leading edge and / or the trailing edge of the recording pulse to increase the output by adding the additional power or the length to increase the output to W0 is 0 of the basic clock period T. A range of 0.5 to 2 times, that is, a range of 0.5T to 2T is particularly preferable, and a range of 0.2T to 2.5T is also possible.
Furthermore, when the mark is recorded, the amount of cooling pulse irradiation after the trailing edge of the pulse is set to 0.1 mW or less for a certain period of time so that recording can be performed with better recording quality, and the recording position can be detected with a high frequency wobble. Can be recorded without loss of joints.

The pulse irradiation pattern is a new format method for a write-once DVD system that uses a semiconductor laser having an oscillation wavelength shorter than that of a CD-based medium. It is an effective method to eliminate, and furthermore, superior to the DVD-R land pre-pit method, it does not cause a data error due to fine cut width control and leakage of the LPP signal to the data part during stamper production. It is a method.
The present invention 2 prescribes a preferable irradiation condition of the cooling pulse provided after the rear end of each pulse, and the irradiation time of the cooling pulse is set to 1/6 to 6/6 of the shortest long space. Preferably, if it is out of this range, it is difficult to obtain the effect of the cooling pulse.
By selecting the pulse waveform as described above, good recording can be performed with low jitter, particularly in high linear velocity recording.

As a preferred mode for carrying out the present invention, the technique for eliminating the buffer underrun described above is applied, and recording is temporarily interrupted when the recording linear speed comes to a planned address at which the maximum linear speed is switched. Therefore, the writing start data to be recorded immediately after switching to the maximum linear velocity is stored in a temporary buffer memory (22 in FIG. 11) (where the address at which the recording linear velocity is to be switched can be rotated at the maximum recording linear velocity). It is necessary to set it to the outer circumference of a minute amount than the address.)
At the same time, the pickup (13 in FIG. 11) is moved to the outermost periphery by the encoder (20 in FIG. 11), and then the address detection is performed to detect the power calibration area provided on the outer periphery from the user use area, In the power calibration area, the rotation is carried out under the control of the rotational speed faster than the linear speed at which recording is interrupted, that is, the maximum linear speed rotational speed.
Then, test writing (OPC) is performed when the rotational speed, the recording frequency, and the power calibration area satisfy the desired conditions, and the optimum recording power Po at the outermost circumference at the highest linear velocity at that time is obtained.
In the present invention, the Po is compared with the optimum recording power Pi at the maximum linear velocity that is previously coded and recorded on the substrate. As described above, when Po> Pi, the expression “(Po + Pi) / 2 + (Po− The recording power obtained by “Pi) ² / Pi” is the recording starting power at the highest linear velocity, and Pi is the recording starting power at the highest linear velocity when Po ≦ Pi. As a result, the recording power at the maximum recording linear velocity is obtained. Needless to say, the maximum linear velocity that can be recorded on the target medium and the optimum recording power and recording waveform at each linear velocity are read and stored in advance.

Furthermore, using the above-mentioned conventional technology, the encoder moves the pickup to a nearby address where data writing should be resumed, and then synchronizes the rotation of the disk and the timing of data writing before resuming the writing at the highest linear velocity. Recording will be resumed.
Since the data to be recorded is stored in the buffer memory as described above, recording at the highest linear velocity is possible, and the optical pickup position is returned to the position before the interrupted address, and the data is read out at the highest linear velocity. Get a signal. On the other hand, recording at the maximum linear velocity can be started by generating an EFM signal on the data writing side inside the encoder and combining these two signals to synchronize. In addition, if the wobble frequency is a high frequency of about 4T to 96T, the phase can be detected more easily, and a recording seam can be formed satisfactorily.
If the recording / reproducing method of the present invention is employed, optimum recording power control at the start of recording at the maximum linear velocity can be performed very effectively, as shown in an embodiment described later.
For example, when the recording linear velocity before the linear velocity switching is 21 m / s and the maximum recording linear velocity after the linear velocity switching is 28 m / s, the recording / reproducing method of the present invention is effective in realizing high-quality recording. Very useful.

The dye-based optical recording medium has to increase the recording power in order to achieve a higher linear velocity, and as a result, thermal interference between marks is more likely to occur. Therefore, the present invention is effective to improve the mark edge breakage when forming the mark.
When recording is performed with the conventional example, the power margin is reduced by causing a shift between the power at which the lowest jitter is obtained and the power at which the error is minimized. Specifically, in high linear velocity recording, the asymmetry of the recording signal tends to be negative at the recording power at which the lowest jitter is obtained, and in error measurement, errors are likely to occur even though the jitter is low. For example, even if the asymmetry is negative, low jitter, and low error, errors are more likely to occur than media recorded near zero asymmetry due to aging of the medium and drive. The present invention has been made to solve this low asymmetry problem.

In addition, even when writing one mark with a plurality of pulse lights (multi-pulse), if the pulse light is optimized, the above-mentioned low asymmetry problem can be solved. When the rise and fall times of light vary, the recording quality itself may vary. Needless to say, this variation is more likely to occur as the linear velocity is recorded.
On the other hand, in the present invention, since recording is performed with one pulse of light per mark, there is an advantage that a recording method with less variation in recording quality can be provided as compared with the multi-pulse light recording. In addition, the address detection during writing has a simpler recording waveform than the multi-pulse method, so the amount of light during recording is easy to average, and not only the amount of reflected light in the space portion but also the amount of light in the mark portion is averaged for address detection. Therefore, even if a cooling pulse of 0.1 mW or less is provided at the rear end of the pulse, there is an advantage that address detection can be performed relatively easily.

Considering the influence of thermal interference, the heating pulse width of the recording pulse for forming the mark having the shortest space length immediately before is distinguished by whether or not the mark length is the shortest length. The heating pulse width of the long mark is set to be longer than the heating pulse width of the mark that is not the shortest length (see, for example, the case where the immediately preceding space length is 3T and the recording mark length is 3T, 4T to 14T in Table 1 described later). Thus, recording with lower jitter can be realized.
Further, the heating pulse width of the recording pulse forming the shortest length mark is distinguished by whether or not the space length immediately before the shortest length mark is the shortest length, and the heating pulse width of the mark having the shortest space length immediately before is short. Is set to be shorter than the heating pulse width of the mark whose preceding space length is not the shortest (see, for example, the case where the recording mark length is 3T and the space length is 3T, 4T to 14T in Table 1 described later). Low jitter recording can be realized.

The correction amount (length) for setting the heating pulse width short is particularly preferably in the range of 0.02T to 0.10T. When the space length immediately before the mark to be formed is the shortest length and the pulse width of the pulse forming the mark is substantially equal to that of the other marks, the space length immediately before the mark is shortened due to thermal interference, and jitter Is slightly worse. Therefore, only in such a case, it is effective to shorten the heating pulse width for recording the mark. Needless to say, it is effective to shorten the front edge of the heating pulse in order to further shorten the pulse width.
In addition, when the space length immediately before the mark to be formed is the shortest length, it is not preferable that the heating pulse width of the pulse for forming the mark is shorter than 0.10 T because the mark length itself becomes too short.
The correction amount (length) when the heating pulse width of the shortest mark is set longer than that of other marks is preferably 0.05T to 0.25T. In particular, when the recording linear velocity increases, it becomes difficult to form the shortest length mark. Therefore, the pulse width of the shortest length mark is increased by correcting within the above range.

Specific examples of the correction amount of the heating pulse width are shown in Table 1 below.

Next, optical characteristics are listed as items necessary for the recording layer.
As an optical characteristic, the refractive index n of the recording layer single layer with respect to light in the wavelength range near the long wavelength near the recording / reproducing wavelength, that is, light in the wavelength range of ± 5 nm of the recording light and the reproducing light is 1.5 ≦ n ≦. 3.0 and the extinction coefficient k is preferably in the range of 0.02 ≦ k ≦ 0.2. When n is less than 1.5, it is not preferable because it is difficult to obtain a sufficient optical change and the recording modulation degree becomes low. When n exceeds 3.0, the wavelength dependence becomes too high, and the recording / reproducing wavelength region However, it is not preferable because an error occurs. Further, when k is less than 0.02, it is not preferable because the recording sensitivity is deteriorated. When k exceeds 0.2, it is difficult to obtain a reflectance of 50% or more.
Note that the DVD is standardized at around 650 nm in a reproduction-only machine, but the wavelength of the recording light of the recording medium is standardized at 650 to 660 nm for general use in addition to 635 nm of the authoring-only medium. However, these wavelengths are only central wavelengths, and can be shifted to the short wavelength side and the long wavelength side due to variations in the manufacturing of the LD. In addition, due to the characteristics of the LD, the wavelength generally shifts to the longer wavelength side when the temperature rises. The present invention is a method that can be carried out at a recording wavelength of 600 to 720 nm including the above wavelength range.

Next, the wobble characteristics of the meandering guide groove provided on the substrate will be described. T for specifying the wobble frequency is a basic clock period. In the case of a DVD (4.7 GB) medium, the time is about 0.133 μm. About 38 nsec. It is.
Normally, the wobble frequency band corresponding to 150T to 400T is used, but this frequency band is too low when writing data, whether it is frequency modulation or phase modulation, and the previous data Is not suitable for high-density recording. On the other hand, the DVD-R is provided with an LPP, and the data writing position is controlled by the LPP signal.
However, in the LPP method, if the signal amplitude of the LPP is too small, the LPP cannot be read satisfactorily. On the contrary, if the LPP is too large, the LPP signal itself leaks into the write data and a data error occurs frequently. , LPP has a constraint of 0.16 ≦ LPPb ≦ 0.32, preferably 0.18 ≦ LPPb ≦ 0.26, and the cut width of the land must be finely controlled when forming the stamper.
On the other hand, if the high-frequency wobble is used, the LPP is not necessary, and the wobble is modulated and synchronized, so that a situation in which data errors occur frequently as in the LPP method does not occur. As defined in Invention 4, the preferred frequency of wobble is 4T to 96T. If the frequency is smaller than 4T, the frequency becomes too high to be detected, and there is a problem in terms of rotation control and address detection reliability. On the other hand, when the frequency is larger than 96T, the frequency is too low and a gap is too wide at the seam when data is additionally written, causing problems such as a reduction in capacity and a reduction in data processing speed.

The wobble amplitude of the DVD medium to which the present invention is applied is the wobble amplitude (Wo) of the signal passing through a suitable filter, for example, 4 MHz, 30 kHz, and a suitable filter, for example, a 30 kHz filter. As long as the ratio Wo / PP of the push-pull signal (PP) satisfies 0.1 ≦ Wo / PP ≦ 0.4, synchronization with the wobble that is the object of the present invention is easy, More preferably, the range is 0.15 ≦ Wo / PP ≦ 0.30. If the value of Wo / PP is less than 0.1, the signal strength is insufficient to achieve synchronization, and if it exceeds 0.4, data portion errors tend to increase. However, as compared with the LPP method, the degree of influence on the data error occurrence of a medium having a large LPP is small, and the data error accompanying the increase in wobble amplitude is moderate.
Further, when creating a stamper, an advanced cut width control technique is required to bring the LPP cut width of the LPP method within the range of 0.16 to 0.32, but in the high frequency wobble method, a high frequency generation source is required. And the wobble swing amount (the circuit that controls the wobble swing amount allows the swing amount to be created arbitrarily reproducibly), the purpose is achieved, so the stamper yield and the media yield can be reduced. It can be improved dramatically.

Further, as the groove shape of the substrate having the above format, when a recording layer is formed by a solvent coating method using an organic dye, a preferable groove depth is 1000 to 2500 mm, and more preferably 1500. ~ 2000cm. If the groove depth is less than 1000 mm, the push-pull signal cannot be obtained sufficiently and tracking control cannot be performed. On the other hand, if the thickness exceeds 2500 mm, the transferability becomes undesirably reduced when the substrate is formed.
Further, when the dye recording layer is provided, the dye groove depth is preferably in the range of 1200 ≦ d1 × m ≦ 160000 when the wobble frequency is mT (m is a natural number) and the dye groove depth is d1. When d1 × m is less than 1200, a sufficient difference signal cannot be obtained, and sufficient tracking cannot be performed at the time of recording / reproduction. Due to the limitation of the depth of the substrate groove due to the transfer limit of the substrate molding described above, it cannot substantially exceed 160000.
In addition, in order to ensure a recording density of 4 to 5 GB, the track pitch needs to be about 0.64 to 0.8 μm. Although the groove width varies depending on the recording material, it can be applied to a width of 0.18 to 0.40 μm in almost all organic materials.

Next, the layer structure of the dye-based write-once DVD medium that is the subject of the present invention, the necessary characteristics of each layer, and the constituent materials will be described.
FIGS. 1A to 1D are layer configuration examples of a normal write-once optical disc, and FIGS. 2A to 2C are layer configuration examples of a normal CD-R medium. ) To (c) are examples of the layer structure of the write-once DVD medium, but the preferred basic structure of the dye-based write-once DVD medium that is the subject of the present invention is as shown in FIGS. A first substrate and a second substrate (protective substrate) are bonded together with an adhesive with a recording layer in between.
The recording layer may be a single organic dye layer or a laminate of an organic dye layer and a reflective layer to increase reflectivity. An undercoat layer or a protective layer may be provided between the recording layer and the substrate, and each layer may have a laminated structure of two or more layers for improving the function. The structure most commonly used is a structure comprising a first substrate / organic dye layer / reflective layer / protective layer / adhesive layer / second substrate (protective substrate).

"substrate"
The substrate must be transparent to the laser used when performing recording / reproduction from the substrate side, but need not be transparent when performing recording / reproduction from the recording layer side. As the substrate material, for example, a polyester resin, an acrylic resin, a polyamide resin, a polycarbonate resin, a polyolefin resin, a phenol resin, an epoxy resin, a polyimide resin such as a polyimide resin, glass, ceramic, metal, or the like can be used. A tracking guide groove or guide pit and a preformat such as an address signal may be formed on the surface of the substrate.

<Recording layer>
The recording layer causes an optical change due to the irradiation of the laser beam and records information by the change, and a material containing an organic dye as a main component is used as the material. Here, the main component means that it contains a sufficient amount of an organic dye necessary for recording and reproduction, but usually only an organic dye is used except for a small amount of additives that are appropriately added as necessary.
Examples of organic dyes include azo, formazan, dipyrromethene, (poly) methine, naphthalocyanine, phthalocyanine, tetraazaporphyrin, squarylium, croconium, pyrylium, naphthoquinone, anthraquinone (in) (Dansylene), xanthene, triphenylmethane, azulene, tetrahydrocholine, phenanthrene, triphenothiazine dyes, or metal complexes thereof. Among these, azo (metal chelate) dye, formazan (metal chelate) dye, squarylium (metal chelate) dye, dipyrromethene (metal chelate) dye, trimethine cyanine dye, and tetraazaporphyrin dye are preferable.
As the thermal decomposition characteristics, the above dyes preferably have a decomposition start temperature of 100 to 360 ° C, particularly preferably 100 to 350 ° C. If the decomposition start temperature exceeds 360 ° C., pit formation at the time of recording is not performed well, and jitter characteristics deteriorate. Further, if the temperature is lower than 100 ° C., the storage stability of the disk deteriorates.

For the purpose of improving optical characteristics, recording sensitivity, signal characteristics, etc., the above dyes may be mixed with other organic dyes, metals, metal compounds, or a layer composed of a dye layer and other organic dyes, metals, metal compounds. May be laminated.
Examples of such metals and metal compounds include In, Te, Bi, Se, Sb, Ge, Sn, Al, Be, TeO ₂ , SnO, As, Cd, and the like. It can be used by laminating.
Furthermore, various materials such as ionomer resin, polyamide resin, vinyl resin, natural polymer, silicone, liquid rubber, or a silane coupling agent may be dispersed and mixed in the dye, For the purpose of improving the properties, stabilizers (for example, transition metal complexes), dispersants, flame retardants, lubricants, antistatic agents, surfactants, plasticizers and the like can be used together.

The recording layer can be formed by ordinary means such as vapor deposition, sputtering, CVD, and solvent coating. When the coating method is used, the above-described dye or the like can be dissolved in an organic solvent, and the coating can be performed by a conventional coating method such as spraying, roller coating, dipping, or spin coating. Organic solvents generally used include alcohols such as methanol, ethanol and isopropanol; ketones such as acetone, methyl ethyl ketone and cyclohexanone; amides such as N, N-dimethylformamide and N, N-dimethylacetamide; sulfoxides such as dimethyl sulfoxide Ethers such as tetrahydrofuran, dioxane, diethyl ether and ethylene glycol monomethyl ether; esters such as methyl acetate and ethyl acetate; aliphatic halogenated hydrocarbons such as chloroform, methylene chloride, dichloroethane, carbon tetrachloride and trichloroethane Aromatics such as benzene, xylene, monochlorobenzene and dichlorobenzene; cellosolves such as methoxyethanol and ethoxyethanol; hexane and penta , Cyclohexane, and hydrocarbons such as methylcyclohexane.
The thickness of the recording layer is 100 to 10 μm, preferably 200 to 2000 μm.

<Underlayer>
The undercoat layer consists of (1) improved adhesion, (2) a barrier such as water or gas, (3) improved storage stability of the recording layer, (4) improved reflectance, and (5) a substrate from a solvent. And (6) guide grooves, guide pits, and preformats. For the purpose of (1), various polymer compounds such as ionomer resin, polyamide resin, vinyl resin, natural resin, natural polymer, silicone, liquid rubber, or a silane coupling agent can be used. For the purposes of (2) and (3), in addition to the above polymer materials, inorganic compounds such as SiO, MgF, SiO ₂ , TiO, ZnO, TiN, and SiN can be used. Furthermore, Zn, Cu Ni, Cr, Ge, Se, Au, Ag, Al, or other metals or metalloids can be used. For the purpose of (4), an organic thin film having a metallic luster made of a metal such as Al, Au, or Ag, a methine dye, a xanthene dye, or the like can be used. For the purposes (5) and (6), an ultraviolet curable resin, a thermosetting resin, a thermoplastic resin, or the like can be used.
The thickness of the undercoat layer is 0.01 to 30 μm, preferably 0.05 to 10 μm.

<Reflective layer>
Examples of the material for the reflective layer include metals such as Au, Ag, Cr, Ni, Al, Fe, and Sn that can be obtained with a high reflectivity and are not easily corroded, but from the viewpoint of reflectivity and productivity. Au, Ag, and Al are particularly preferable. In addition, these metals and metalloids may be used alone or as two or more alloys.
Examples of the film forming method include vapor deposition and sputtering, and the film thickness is 50 to 5000 mm, preferably 100 to 3000 mm.

《Protective layer, hard coat layer on substrate surface》
The protective layer and the hard coat layer on the substrate surface are (1) protection from scratches, dust and dirt on the recording layer (reflection / absorption layer), (2) improvement in storage stability of the recording layer (reflection / absorption layer), (3 ) Used for the purpose of improving the reflectance. For these purposes, the same material as the undercoat layer can be used. Also heat of polymethyl acrylate resin, polycarbonate resin, epoxy resin, polystyrene resin, polyester resin, cellulose resin, aliphatic hydrocarbon resin, natural rubber, styrene butadiene resin, chloroprene rubber, wax, alkyd resin, drying oil, rosin, etc. Organic materials such as softening and heat-melting resins can also be used. The most preferable is an ultraviolet curable resin excellent in productivity.
The film thickness of the protective layer or the substrate surface hard coat layer is 0.01 to 30 μm, preferably 0.05 to 10 μm.
As in the case of the recording layer, the undercoat layer, protective layer and substrate surface hard coat layer may contain a stabilizer, a dispersant, a flame retardant, a lubricant, an antistatic agent, a surfactant, a plasticizer, and the like. it can.

《Protective substrate》
The protective substrate must be transparent to the laser beam used when the laser beam is irradiated from the protective substrate side, but may not be transparent when used as a simple protective plate.
The protective substrate material that can be used is exactly the same as the above substrate material, such as polyester resin, acrylic resin, polyamide resin, polycarbonate resin, polyolefin resin, phenol resin, epoxy resin, polyimide resin, or glass, ceramic, metal, etc. Can be used.
<Adhesive layer>
Any material can be used as the material for the adhesive layer as long as it can adhere two recording media. In view of productivity, an ultraviolet curable adhesive or a hot-melt adhesive is preferable.

Next, the recording / reproducing apparatus of the present invention will be described.
An optical disc is used as a device for recording large-capacity information. The optical disc is usually recorded and reproduced by an optical disc drive (recording / reproducing device). Here, an outline of the configuration of the optical disc and the optical disc drive will be described.
DVD-RAM / WO, DVD-R, DVD + R, and DVD-RAM, DVD-RW, and DVD + RW discs are writable (recordable) DVDs (Digital Versatile Discs). DVD-RAM / WO, DVD-R, and DVD + R are DVDs that can be written only once (also referred to as DVD Write Once). DVD-RAM, DVD-RW, and DVD + RW are DVDs that can be written a plurality of times. Information is recorded / reproduced on these optical disks such as DVD + R and DVD + RW disks by a drive as shown in FIG.

  FIG. 11 is a functional block diagram showing an example of the configuration of the main part of the optical disc drive. In the figure, 11 is an optical disk, 12 is a spindle motor, 13 is an optical pickup, 14 is a motor driver, 15 is a read amplifier, 16 is a servo means, 17 is a DVD decoder, 18 is an ADIP decoder, 19 is a laser controller, and 20 is a DVD. Encoder, 21 DVD-ROM encoder, 22 buffer RAM, 23 buffer manager, 24 DVD-ROM decoder, 25 API / SCSI interface, 26 D / A converter, 27 ROM, 28 CPU, 29 RAM indicates LB, laser light, and Audio indicates an audio output signal.

In FIG. 11, the arrow indicates the direction in which data mainly flows, and in order to simplify the drawing, the CPU 28 that controls each block in FIG. Is omitted. The ROM 27 stores a control program written in a code readable by the CPU 28. When the optical disk drive is turned on, the program is loaded into a main memory (not shown), and the CPU 28 controls the operation of each unit according to the program and temporarily stores data necessary for the control. Is stored in the RAM 29.
The configuration and operation of the optical disk drive are as follows. The optical disk 11 is rotationally driven by a spindle motor 12. The spindle motor 12 is controlled by the motor driver 14 and the servo means 16 so that the linear velocity or the angular velocity is constant. This linear velocity or angular velocity can be changed stepwise.

The optical pickup 13 includes a semiconductor laser, an optical system, a focus actuator, a track actuator, a light receiving element, and a position sensor (not shown), and irradiates the optical disk 11 with a laser beam LB. The optical pickup 13 can be moved in the sledge direction by a seek motor. These focus actuator, track actuator, and seek motor are positioned at a target location on the optical disk 11 by the motor driver 14 and the servo means 16 based on signals obtained from the light receiving element and the position sensor. To be controlled.
At the time of reading, the reproduction signal obtained by the optical pickup 13 is amplified and binarized by the read amplifier 15 and then input to the DVD decoder 17. The input binarized data is demodulated 8/16 in the DVD decoder 17. Note that the recording data is modulated in units of 8 bits and modulated (8/16 modulation). In this modulation, 8 bits are converted to 16 bits. In this case, the combined bits are attached so that the number of previous “1” s and “0” s are equal on average. This is called “DC component suppression”, and the slice level fluctuation of the DC-cut reproduction signal is suppressed.

The demodulated data is subjected to deinterleaving and error correction. Thereafter, this data is input to the DVD-ROM decoder 24, and further error correction processing is performed in order to increase the reliability of the data. The data that has been subjected to the error correction processing twice as described above is temporarily stored in the buffer RAM 22 by the buffer manager 23, and is arranged as sector data to the host computer (not shown) via the ATAPI / SCSI interface 25. It is transferred at a stretch. In the case of music data, the data output from the DVD decoder 17 is input to the D / A converter 26 and extracted as an analog audio output signal Audio.
At the time of writing, data sent from the host computer through the ATAPI / SCSI interface 25 is temporarily stored in the buffer RAM 22 by the buffer manager 23. Thereafter, the write operation is started. In this case, it is necessary to position the laser spot at the write start point before that. In DVD + RW / + R, this point is calculated | required by the wobble signal previously carved on the optical disk 11 by the meandering of the track | truck.

Note that the above points are obtained by land pre-pits instead of wobble signals in DVD-RW / -R, and by pre-pits in DVD-RAM / RAM / WO.
The wobble signal in the DVD + RW / + R disc includes address information called ADIP (ADless In Pre-groove), and this information is extracted by the ADIP decoder 18. The synchronization signal generated by the ADIP decoder 18 is input to the DVD encoder 20 so that data can be written at an accurate position on the optical disk 11. The data in the buffer RAM 22 is subjected to error correction code addition and interleaving in the DVD-ROM encoder 21 and the DVD encoder 20, and the optical disk according to the recording power and recording waveform of the present invention is passed through the laser controller 19 and the optical pickup 13. 11 is recorded.

The recording / reproducing apparatus of the present invention 9 has a wobble in the guide groove of the substrate, and a dye-based recordable DVD in which CLV maximum linear velocity recording conditions and CLV linear velocity recording conditions other than the maximum linear velocity are pre-coded and recorded. When performing recording / reproduction of the medium, in the innermost circumference, recording starts at a CLV linear speed condition other than the maximum linear speed, and the recording is switched from a radial position where rotation at the highest linear speed is possible to recording at the highest linear speed. At the same time, the optimum recording power Po at the highest linear velocity once optimized by performing trial writing in the outermost power calibration area, and the optimum recording power at the highest linear velocity previously encoded and recorded on the medium When Po> Pi, the recording power obtained by the formula “(Po + Pi) / 2 + (Po−Pi) ² / Pi” is set as the recording start recording power at the highest linear velocity, and Po ≦ Pi In the case of Pi Because it has a function of a recording start recording power at a high linear velocity high-quality recording at a high linear velocity can be realized.

The shortest mark is always recorded with one pulsed light of power W0, and the second shortest mark is based on power W0, or power W1 lower than W0, or power W2 lower than W1, The rear end portion is recorded with one pulsed light whose output is increased to the power W0 or W1 for a predetermined time, and the third and subsequent marks from the shortest are based on the power W2 and the pulse front end portion and / or the rear end portion Is recorded with one pulsed light whose power is increased to W0 or W1 for a certain period of time, and at the time of mark recording, a cooling pulse is irradiated after the trailing edge of the above-mentioned pulse of all the marks, and the irradiation light quantity is determined for a certain period of time. Since it has a function of making it 0.1 mW or less, it is possible to further improve the recording quality at a high linear velocity.
The recording / reproducing apparatus of the present invention 10 has a function of setting the time for irradiating the cooling pulse after the rear end of the pulse to a length of 1/6 to 6/6 of the shortest long space, and therefore employs a more preferable cooling pulse range. As a result, the recording quality can be further improved.

Further, the recording / reproducing apparatus of the present invention 11 distinguishes the heating pulse width of the recording pulse for forming the mark having the shortest space length immediately before depending on whether or not the mark length is the shortest length. The heating pulse width of the long mark is set longer than the heating pulse width of the mark that is not the shortest length, and the heating pulse width of the recording pulse that forms the shortest length mark is set so that the space length immediately before the shortest mark is the shortest length. It is distinguished by whether or not there is a function to set the heating pulse width of the mark with the shortest preceding space length shorter than the heating pulse width of the mark with the shortest preceding space length, so high quality recording, That is, low jitter can be realized.
The method for obtaining address information may be a method for obtaining address information from land prepits or prepits.

12 is a schematic diagram of an information processing apparatus using the optical disk drive shown in FIG.
The information processing apparatus includes a main control device, an interface, a recording device, an input device, a display device, and the like.
The main controller includes a CPU (central processing unit, microcomputer), a main memory (none of which are shown), and the like, and controls the entire host computer.
The interface is a two-way communication interface with the optical disc drive, and conforms to standard interfaces such as ATAPI and SCSI. The interface is connected to the optical disk drive interface 25 described above. The connection form between the interfaces may be not only a cable connection using a communication line such as a communication cable (for example, a SCSI cable) but also a wireless connection using infrared rays.

The recording device (HDD, hard disk) stores a program written in a code readable by the microcomputer of the main control device. When the information processing apparatus is powered on, the program is loaded into the main memory of the main control apparatus.
The display device includes a display unit (not shown) such as a CRT, a liquid crystal display (LCD), or a plasma display panel (PDP), and displays various information from the control device.
The input device includes at least one input medium (not shown) such as a keyboard, a mouse, and a pointing device, for example, and notifies the main control device of various information input by the user. Note that information from the input medium may be input in a wireless manner. Further, as an integrated display device and input device, there is a CRT with a touch panel, for example. The information processing apparatus is equipped with an operating system (OS). It is assumed that all devices constituting the information processing apparatus are managed by the OS.

  According to the present invention, it is possible to accurately optimize the recording power at the maximum linear velocity recording using a simple recording power control method, and it is possible to improve the recording quality when the recording linear velocity is switched. In addition, if the write waveform defined in the present invention is used, recording with low jitter and low error rate becomes possible particularly on the high linear velocity side. Furthermore, the high-frequency wobble format that can be manufactured more easily than the land pre-pit format used in the DVD-R can efficiently perform the writing of the data portion, and the CD-R that is currently manufactured in large quantities. It is possible to provide a recording medium having almost the same format as DC-RW.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further more concretely, this invention is not limited by these Examples.

Examples 1-9, Comparative Examples 1-3
The following [Chemical Formula 1] and [Chemical Formula 2] are formed on an injection-molded polycarbonate substrate having a groove depth of 1660 mm, a half width of 0.38 μm, a track pitch of 0.74 μm, a thickness of 0.6 mm corresponding to a wobble frequency of 32T, and an outer diameter of 120 mm. The pigment compound was weighed 65:35 in a weight ratio, dissolved in 2,2,3,3-tetrafluoro-1-propanol and applied with a spinner to form an organic pigment layer having a thickness of 900 mm, followed by 30 at 85 ° C. Dried for minutes.
Next, an Ag reflective layer having a thickness of 1100 mm is provided by sputtering, and a protective layer having a thickness of 5 μm made of an acrylic photopolymer is provided thereon, and then an injection molded polycarbonate having a thickness of 0.6 mm and an outer diameter of 120 mm. An optical recording medium was obtained by bonding the flat substrate with an acrylic photopolymer.

A semiconductor laser beam having an oscillation wavelength of 658 nm and a beam diameter of 0.9 μm is used for the optical recording medium, and an EFM signal (minimum pit length of about 0.4 microns) is tracked while tracking. / S, W1 / W2 = 1.48, W0 / W1 = 1.04, cooling power 0 mW, cooling pulse length 2T, recording was performed by switching the optimum recording power from the disk radial position 39 mm, and jitter was measured.
Further, recording was performed under the same conditions as above except that the oscillation wavelength was changed to 665 nm and the switching radius position of the optimum recording power was changed to 40 mm, and jitter was measured.
Furthermore, recording was performed under the same conditions as above except that the oscillation wavelength was changed to 665 nm and the switching radius position of the optimum recording power was changed to 58 mm, and jitter was measured.
The measurement results are shown in FIG.
The optimum recording power of 24 mW at 658 nm and the radial position of 39 mm in FIG. 10 corresponds to the power (Pi) recorded by being coded on the substrate.
Further, the optimum recording power 29 mW of 665 nm and 58 mW corresponds to the power (Po) calculated in the outermost peripheral power calibration area in a state where the LD has a longer wavelength. (Conditions were set assuming the case where the temperature inside the drive rises, the LD becomes longer in wavelength, and the optimum recording power increases.)
The optimum recording power of 27.7 mW at 665 nm and the radial position of 40 mm (medium circumference) corresponds to the actual optimum power (Pr) at the switching position of the highest recording linear velocity.
On the other hand, when the values of Po and Pi are substituted into the formula “(Po + Pi) / 2 + (Po−Pi) ² / Pi” of the present invention, the result is 27.5 mW, which is substantially equal to the Pr 27.7 mW. Is extremely effective for controlling the optimum recording power.

In addition, an EFM signal (minimum pit length of about 0.4 microns) is recorded on the above optical recording medium while tracking using a semiconductor laser beam having an oscillation wavelength of 660 nm and a beam diameter of 0.9 μm. Recording was performed with a recording power at which Bottom Jitter (bottom jitter) was minimized at the linear velocity, and the jitter value, asymmetry, and number of PI errors were obtained by reproducing the portion. The waveform of the recording laser beam is as shown in FIGS. W0 is the pulse power of the shortest length mark, or the power of the mark other than the shortest length mark is increased, W1 is the power of the mark other than the shortest length mark, and the output is increased by adding the power, W2 is This is the base power of the mark other than the shortest length mark (power without addition).
Furthermore, the pulse lengths shown in FIGS. 4 to 9 were used as the recording linear velocities of 21 m / s and 28 m / s, but the present invention is not limited to this.
The results are shown in Table 2. The jitter, asymmetry, and PI error were all good.

上記表３から分るように、ＬＰＰフォーマットのサンプルでは、比較例２〜３のようにＬＰＰｂが大きくなると、ジッタが良好であってもＰＩエラーが増加してしまう。また、比較例１のように、ジッタ、アシンメトリ、ＰＩエラーに問題がなくても、ＬＰＰｂが０．１６を下回るレベルであると、実用されている装置でのアドレス検出が不可能となってしまうことが確認された。 In addition, an EFM signal (minimum pit length of about 0.4 microns) is recorded on the above optical recording medium while tracking using a semiconductor laser beam having an oscillation wavelength of 660 nm and a beam diameter of 0.9 μm. Recording was performed with a recording power at which the bottom jitter was minimized under the conditions of linear velocity and Table 1 correction, and the jitter value, asymmetry, and number of PI errors were obtained by reproducing the portion.
In Comparative Examples 1 to 3, the production conditions were the same as in the examples using the prototype condition stamper and the molded substrate in which the size of the LPPb in the LPP format implemented in the DVD-R was changed (changed). An optical recording medium was prepared and evaluated in the same manner as in the examples.

As can be seen from Table 3, in the LPP format sample, when the LPPb increases as in Comparative Examples 2 to 3, the PI error increases even if the jitter is good. Further, as in Comparative Example 1, even if there is no problem in jitter, asymmetry, and PI error, if LPPb is at a level below 0.16, it is impossible to detect an address in a practical device. It was confirmed.

OPC is used to determine the optimum recording power of an optical recording medium in a drive that is actually used. Specifically, a small amount of data is test-recorded by varying (changing) the recording power in the OPC area (usually the innermost circumference), and the asymmetry, β or jitter of the test recording waveform with the power varied. Asymmetry, optimum value of β, or power that minimizes jitter is obtained. In CD-R and DVD ± R, it is known that in the normal case, both asymmetry and β are good near 0 (zero), but shift to the plus side in low-speed recording and to the minus side in high-speed recording.
In the present embodiment, a method of calculating the optimum recording power of OPC with the power that minimizes the jitter is used. Further, in this embodiment, recording / reproduction was performed by experimentally reproducing the conditions assumed for the actually used drive.
In this embodiment, it is assumed that the recording linear velocity is switched from 21 m / s to 28 m / s near the radial position of 40 mm. Recording at 21 m / s is possible using conventional techniques. In other words, when recording at 21 m / s, the optimum recording power is obtained by performing OPC in the innermost circumferential OPC area, and recording starts from the inner circumferential user area with the optimum recording power. High recording is possible. On the other hand, it is not realistic to carry out a rotation speed of 28 m / s on the innermost circumference because rotation is impossible unless an expensive spindle motor or control device is used. Therefore, the optimum recording power at the time of starting recording at 28 m / s from around 40 mm is only a reference value of the optimum recording power at 28 m / s previously coded and recorded on the substrate of the recording medium.

However, as described above, when actual drive recording is considered, continuous recording has been performed at 21 m / s up to around 40 mm, the temperature in the drive chamber rises, and the recording LD has a longer wavelength. The increase in the wavelength of the LD is about 0.6 nm / ° C., and if the internal temperature increases by 10 ° C., the LD shift becomes 6 nm. This optimum recording power at 28 m / s recorded in advance on a recording medium substrate does not take into account the increase in the wavelength of the LD. Therefore, in the condition setting of the present embodiment, it was assumed that the continuous temperature at 21 m / s was implemented, and as a result, the temperature inside the drive cabinet rose slightly over 10 ° C. That is, the recording power at which the recording wavelength is 658 nm (test condition wavelength for DVD medium recording), the recording linear velocity is 28 m / s, and the recording power is shaken at the radial position of 39 mm (near 40 mm), and the minimum jitter is obtained. The Pi is coded and recorded on the recording medium.
On the other hand, the recording power at which the recording wavelength is 665 nm (7 nm longer wavelength), the recording linear velocity is 28 m / s, and the recording power at the radial position of 40 mm is varied to obtain the minimum jitter, the drive is increased by about 10 ° C. The actual optimum recording power Pr at 40 mm under the assumption that the However, OPC (trial writing) in the vicinity of 40 mm, which is the user area, is impossible in an actual system. Therefore, in order to calculate Pr with high accuracy, recording / reproduction is performed by changing the recording power at a recording wavelength of 665 nm, a recording linear velocity of 28 m / s, and a radial position of 58 mm (outermost circumference, outside the user's use area), thereby obtaining a minimum jitter. The power that is generated is Po (the same as that performed for OPC outside the outermost user area).
In this embodiment, it is assumed that the temperature rises by 10 ° C. However, the present invention is effective even when the temperature rise is 5 ° C. or 15 ° C.

(A)-(d) The figure which shows the example of a layer structure of a normal write-once type optical recording medium. (A)-(c) The figure which shows the example of a layer structure of a normal CD-R medium. (A)-(c) The figure which shows the layer structural example of a pigment | dye type recordable DVD medium. The figure which shows the power control waveform example 1 which concerns on this invention 2 and 3 for recording linear velocity 28m / s. The figure which shows the power control waveform example 2 which concerns on this invention 2, 3 for recording linear velocity 28m / s. The figure which shows the power control waveform example 3 which concerns on this invention 2, 3 for recording linear velocity 28m / s. The figure which shows the power control waveform example 4 which concerns on this invention 2, 3 for recording linear velocity 28m / s. The figure which shows the power control waveform example 5 which concerns on this invention 2, 3 for recording linear velocity 21m / s. The figure which shows the power control waveform example 6 which concerns on this invention 2, 3 for recording linear velocity 21m / s. The figure which shows the relationship between the recording power and jitter in each radial position. The functional block diagram which shows an example of the principal part structure of an optical disk drive. FIG. 12 is a schematic diagram of an information processing apparatus using the optical disc drive shown in FIG. 11.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 2 Recording layer 3 Undercoat layer 4 Protective layer 5 Hard coat layer 6 Reflective layer 7 Protective substrate 8 Adhesive layer space space mark Mark Cooling Area Cooling area T Basic clock period n An integer greater than or equal to n 'An integer greater than or equal to 3 ps Space length in cm cm Recording mark length W0 Recording power of the shortest length mark, higher power of the mark other than the shortest length mark W1 Higher output power of the mark other than the shortest length mark by adding additional power W2 Shortest length mark Base power of marks other than (power without addition)

Claims (11)

A recording layer mainly composed of an organic dye is provided on a disc-shaped substrate having a guide groove provided with a wobble, and a CLV linear velocity recording other than the CLV maximum linear velocity recording condition and the maximum linear velocity is provided at a predetermined position of the substrate. When recording / reproduction of a write-once type DVD medium that has been coded and recorded in advance, recording can be started on the innermost circumference under CLV linear speed conditions other than the maximum linear speed, and rotation at the maximum linear speed becomes possible. When switching from the radial position to the recording at the highest linear velocity, the optimum recording power Po at the highest linear velocity, which has been optimized by performing trial writing in the outermost power calibration area, is recorded on the substrate in advance. Is compared with the optimum recording power Pi at the highest linear velocity, and when Po> Pi, the recording power obtained by the expression “(Po + Pi) / 2 + (Po−Pi) ² / Pi” is the highest linear velocity. Recording start with recording power and , Po ≦ Pi, Pi is the recording start recording power at the maximum linear velocity, and the shortest mark is always recorded with one pulsed light of power W0, and the second shortest mark is the power W0, Alternatively, the shorter one is recorded with one pulse light whose power is lower than W0 or lower than W1 and whose pulse front end and / or rear end is increased in power W0 or W1 for a certain period of time. The third and subsequent marks are recorded with one pulsed light whose output is increased to a power W0 or W1 for a certain period of time based on the power W2, and at the time of mark recording, A recording / reproducing method characterized in that a cooling pulse is irradiated after the trailing edge of the pulse of the mark, and the irradiation light quantity is set to 0.1 mW or less for a predetermined time. 2. The recording / reproducing method according to claim 1, wherein the irradiation time of the cooling pulse after the rear end of the pulse is set to 1/6 to 6/6 of the shortest long space.   The heating pulse width of the recording pulse that forms the mark with the shortest space length immediately before is distinguished by whether or not the mark length is the shortest length, and the heating pulse width of the shortest mark is not the shortest length mark. The heating pulse width of the recording pulse for forming the shortest length mark is distinguished by whether or not the space length immediately before the shortest mark is the shortest length. 3. The recording / reproducing method according to claim 1, wherein the heating pulse width of the mark having the shortest length is set shorter than the heating pulse width of the mark having the shortest preceding space length.   4. The recording / reproducing method according to claim 1, wherein the wobble has a frequency corresponding to 4T to 96T, where T is a basic clock period.   5. The recording / reproducing method according to claim 1, wherein the wavelength of the recording light is 600 to 720 nm.   The recording layer single layer has a refractive index n of 1.5 ≦ n ≦ 3.0 and an extinction coefficient k of 0.02 ≦ k ≦ with respect to light in the wavelength range of the recording light and reproducing light wavelength ± 5 nm. 6. The recording / reproducing method according to claim 1, wherein the recording / reproducing method is 0.2.   The recordable DVD medium has at least one layer selected from a reflective layer, a protective layer, an adhesive layer, a protective substrate, and a substrate surface hard coat layer as a constituent layer other than the recording layer on the substrate. Item 7. The recording / reproducing method according to any one of Items 1 to 6.   Adhesive layer for providing a recording medium having a double-sided structure by bonding two substrates having a guide groove in which at least one substrate is provided with wobbles, and an adhesive used for the adhesive layer 8. The recording / reproducing method according to claim 7, wherein is a UV curable resin. Recording / reproduction of a dye-based write-once DVD medium having a wobble in the guide groove of the substrate, in which CLV maximum linear velocity recording conditions and CLV linear velocity recording conditions other than the maximum linear velocity are encoded and recorded in advance. At the innermost circumference, when recording is started at a CLV linear speed condition other than the highest linear speed and switching from a radial position where rotation at the highest linear speed is possible to recording at the highest linear speed, The optimum recording power Po at the highest linear velocity optimized by performing trial writing in the power calibration area is compared with the optimum recording power Pi at the highest linear velocity that has been encoded and recorded in advance on the medium. If> Pi, the recording power obtained by the formula “(Po + Pi) / 2 + (Po−Pi) ² / Pi” is set as the recording start recording power at the highest linear velocity, and if Po ≦ Pi, Pi is Record start record at maximum linear velocity In addition, the shortest mark is always recorded with one pulse light of power W0, and the second shortest mark is pulsed based on power W0, power W1 lower than W0, or power W2 lower than W1. The front end portion and / or the rear end portion are recorded with one pulsed light whose power is increased to a power W0 or W1 for a certain period of time, and the third and subsequent marks from the shortest are based on the power W2 and / or the pulse front end portion and / or The rear end portion is recorded with one pulse light whose power is increased to a power W0 or W1 for a certain time, and at the time of mark recording, a cooling pulse is irradiated after the rear end portion of the pulse of all the marks, and the irradiation light amount Recording / reproducing apparatus, characterized in that it has a function of keeping the time constant at 0.1 mW or less. 10. The recording / reproducing apparatus according to claim 9, wherein the irradiation time of the cooling pulse after the rear end of the pulse has a function of setting the length to 1/6 to 6/6 of the shortest long space.   The heating pulse width of the recording pulse that forms the mark with the shortest space length immediately before is distinguished by whether or not the mark length is the shortest length, and the heating pulse width of the shortest mark is not the shortest length mark. The heating pulse width of the recording pulse for forming the shortest length mark is distinguished by whether or not the space length immediately before the shortest mark is the shortest length. 11. The recording / reproducing apparatus according to claim 9, wherein the recording / reproducing apparatus has a function of setting a heating pulse width of a mark having the shortest length shorter than a heating pulse width of a mark having a shortest preceding space length.

Images