Patent Application
20100020664
The present invention relates to a recording strategy adjustment method and an optical disc recording and reproducing device.
Recently, optical disc devices have been often used for a peripheral device of an information processing device and an AV (Audio Visual) apparatus recently. The optical disc device can read information recorded to an optical disc and write information to the optical disc by using laser light.
On an optical disc, recording marks are formed thereon by applying heat to a recording layer on the optical disc to change characteristics of material constituting the recording layer. The recording marks are formed on the basis of recording data. It is important to control the heat applied to the recording layer in order to appropriately form recording marks corresponding to recording data. When the calorific value applied to the recording layer is small when a specific recording mark is formed, the recording mark cannot be adequately formed. When the calorific value applied to the recording layer is large, the form of the recording mark becomes inappropriate. In addition, it exerts an undesirable influence on the formation of other neighboring recording marks.
Accordingly, it is very important in optical disc devices to appropriately control the output of laser light. The control of the laser light is carried out by changing the shape of waveform, which is called the recording strategy. The waveform represented by the recording strategy shows output levels of the record power, the bias power, and the like by the amplitude and shows irradiation time of the laser light for the mark formation by the pulse width (a temporal direction) of the laser pulse for recording.
As shown in
In a case of the HD DVD (High Definition DVD) that is a next-generation DVD, the write once HD DVD-R and the rewritable HD DVD-RW or HD DVD-RAM (hereinafter referred to as the HD DVD family when referring them totally) employ the multi-pulse type recording strategy. The recording strategy greatly influences the recording and reproducing performance of the optical disc. Accordingly, many types of recording strategy adjustment methods are known.
Japanese Laid-Open Patent Application JP-P2000-182244A describes a technique for: allocating several levels to parameters of the record power and the recording strategy; performing experiments on each combination in a comprehensive manner; and selecting the most suitable strategy. In addition, Japanese Laid-Open Patent Application JP-P2000-30254A describes a technique for: separately carrying out adjustment of a parameter of the recording strategy and adjustment of the record power; and determining the record power by referring a theoretical mark length as a guideline. Moreover, Japanese Laid-Open Patent Application JP-P2001-511289A describes a technique for: measuring an anterior edge jitter and a posterior edge jitter from a reproduced signal in test recording-and-reproducing; and separately determining the anterior edge jitter and the posterior edge jitter by adjusting parameters which influence only the anterior edge or the posterior edge (an individual power of recording strategy configuration pulse, a combination of shapes of waveforms, and the like).
Japanese Laid-Open Patent Application JP-P2001-155340A describes a technique that is applicable to the CAV (Constant Angular Velocity) recording, the ZCAV (Zoned CAV) recording, or the CLV (Constant Linear Velocity) recording of any velocity and that carries out the recording in a simple control method. In this technique, when the recording mark is formed on an optical recording medium having a variable recording linear velocity by the multi-pulse method, the record power is allocated with respect to a pulse train for forming the recording mark for each type of the pulse on the basis of: an emission pattern optimized at the configurable highest linear velocity; and a pulse length configuration, and thus the above-mentioned pulse train is generated by more than 2 different record powers. Then, each of the record powers is controlled depending on: the recording linear velocity; or a recording position of an optical recording medium. As in this technique, even if the record power in accordance with the recording linear velocity or the recording position is controlled, the recording can be carried out in low jitters within a practical linear velocity even in a case where an emission pulse length of the recording strategy is fixed to be constant.
Japanese Laid-Open Patent Application JP-P2003-203343A discloses a technique for adjusting the recording strategies of the CD-R and the DVD-R. Japanese Laid-Open Patent Application JP-P2005-216347A discloses a technique for adjusting the recording strategy of the DVD-R.
In the high-density next-generation optical disc (the HD DVD and the BD (Blu-ray Disc)), the reading and the writing to the disc are carried out by applying laser light whose light source wavelength is about 400 to 410 nm (a short wavelength laser). Among the recordable media accepting the above-mentioned short wavelength laser, there are roughly two types of recording layers of the write once media; one employs inorganic material and the other employs organic material. The inorganic material has the H/L (High-to-Low) characteristic that lowers reflectivity of a recording mark portion formed by irradiating a laser light than reflectivity before the laser light irradiation. On the other hand, the organic material has the L/H (Low-to-High) characteristic that increases reflectivity of the recording mark portion.
Japanese Laid-Open Patent Application JP-P2005-116058A describes a technique regarding a write once medium using inorganic material. Japanese Laid-Open Patent Application JP-P2005-297407A describes a technique regarding a write once medium using organic dye material. In addition, Japanese Laid-Open Patent Application JP-P 2005-297407A describes a recording waveform that includes a record power and a bias power and has the bias power in a space portion in response to the high-density next-generation optical disc. The shape of this waveform is equivalent to that used for rewritable media, and it can be found that, unlike conventional ways, a bias power higher than before is required in next-generation write once media.
The HD DVD which is a next generation DVD has much higher recording density (more than three times) as compared with the conventional DVD, and employs the PRML (Partial Response Maximum Likelihood) technique to read a signal. The PRML technique is known as a technique for carrying out the decoding by: preliminarily estimating interference between record signals; and forecasting a probable signal pattern. For example, “Nakano et al., Signal Processing Technologies for next-generation DVD, ITE technical report, Vol. 27, No. 43, pp. 13-16, MMS2003-48, CE2003-53 (July, 2003)” describes a technique regarding the PRML. For the HD DVD, the PRML categorized in the PR (12221) being a very large interference class is used. That is to say, it means that states of an anterior edge and a posterior edge of recording marks existing before and after a certain mark greatly influence the reproduced signal. In addition, this means that adjustment of the recording strategy will be extremely delicate.
In a case of carrying out the PRML detection, there are some indexes used for evaluating a signal quality of reproduced waveform. For example, in Japanese Journal of Applied Physics Vol. 43, No. 7B, 2004, pp. 4859-4862 “Signal-to-Noise Ratio in a PRML Detection”. S. OHKUBO et al., a technique regarding the PRSNR (Partial Response Signal to Noise ratio) is described as one example thereof.
This is an index for the alternative to the jitter used for evaluating a signal quality of reproduced waveform of conventional DVDs. In a high density optical disc such as the HD DVD, it is sometimes difficult for a conventional jitter to evaluate a signal quality of reproduced waveform The PRSNR is an index employed as a signal quality evaluation index alternative to the jitter in the HD DVD family, and is an SNR in the PRML. The PRSNR can be converted into an error rate, it means that the higher this value is, the more superior the signal quality is, and thereby the PRSNR is opposite to the jitter and the error rate. In addition, it has been known that the value is required to be 15 or more as a standard of performance in the PRSNR.
In addition, as another method for evaluating quality of a reproduced waveform, there is a method for directly obtaining the number of error bytes, an error rate, and a PI error. The PI error means the total number of rows in which errors have been detected on the basis of the parity on an inner side of the ECC (Error Correction Code), and is used in qualitatively almost the same meaning as that of the error rate. In the HD DVD, a modulation code that is also different from that of conventional DVDs is used. That is a modulation code called the ETM (Eight to Twelve Modulation) whose shortest mark or shortest space length is 2 T (T is a channel clock period). Meanwhile, the conventional DVD uses a modulation code called the EFM whose shortest mark or shortest space length is 3 T. Accordingly, there configuration of the recording strategy are different from each other.
Additionally, in the HD DVD, a modulation code that is also different from that of conventional DVDs is used. That is a modulation code called the ETM (Eight to Twelve Modulation) whose shortest mark or shortest space length is 2 T (T is a channel clock period). Meanwhile, the conventional DVD uses a modulation code called the EFM whose shortest mark or shortest space length is 3 T. Accordingly, there configuration of the recording strategy are different from each other. For example, in a case of the DVD-R, when a recording mark of length kT (k is a natural number of 3 or more) is recorded, the recording is sometimes carried out by k-2 pulses, however, in a case of the HD DVD-R, since the shortest recording mark length is 2 T, an output pulse cannot exist in 2 T when the recording is carried out by the k-2 pulses. That is, the recording has to be carried out by at least k-1 pulses. This means that is not simply an argument about the number of pulses but requirements to originally change a way of thinking about the configuration of the recording strategy in the DVD and the HD DVD. That is, knowledge of the DVD cannot be used so effectively.
In a high density optical disc such as the HD DVD, it is required to adjust the recording strategy with high accuracy. In addition, an adjustment suitable for the PRML detection that is not used in conventional DVDs is required. This is because the PRML detection is a detection method positively using an intersymbol interference of recorded marks. In such a case, each parameter of the recording strategy often influences with one another, and it accordingly becomes difficult to obtain an optimum recording strategy through a rough adjustment where each parameter independently influence a signal quality such as the technique described in Japanese Laid-Open Patent Application JP-P2000-182244A. In addition, in a case where a recording mark (or apace) is influenced by recording marks before and after the recording mark because the intersymbol interference rapidly increases due to the high density even when the parameter is adjusted by introducing an index using a theoretical value of the longest mark (there is no difference between widths of a mark and a space), it becomes difficult to obtain an optimum recording strategy even in the technique described in Japanese Laid-Open Patent Application JP-P2000-30254A.
Moreover, also in a technique described in Japanese Laid-Open Patent Application JP-P2001-511289A, it is not defined which edge has to be moved in which pulse. In addition, since the power is ambiguous; whether the power means powers of all pulses or a power of individual pulse, it is not described which adjustment has to be preferentially carried out, and there are so many combinations in a case where all of them are tentatively combined, it is difficult to adjust an optimum recording strategy at a high speed.
Japanese Laid-Open Patent Application JP-P2003-203343A describes that the adjustment is carried out with a fixed record power. But it is difficult to carry out high speed adjustment because a plurality of combinations of a top pulse and a multi-pulse are required. In addition, since a portion to be adjusted and an extent of the adjustment are not described, actual application is difficult. Moreover, the conventional technique is prepared for not the PRML detection but a level slice detection (a binary detection for judging whether the power is larger or weaker than the slice level), thereby cannot be directly used for a system using the PRML.
In addition, the techniques described in Japanese Laid-Open Patent Application JP-P2001-511289A, Japanese Laid-Open Patent Application JP-P2003-203343A, and Japanese Laid-Open Patent Application JP-P2005-216347A are adjustment methods not prepared for the PRML detection, and are old methods using the conventional jitter. In high density optical discs such as the HD DVD, the jitter that is a signal index cannot be measured already. Moreover, unlike the HD DVD, the methods are prepared for a modulation code where a signal of 3 T or more exists, and a configuration of the recording strategy is also different from those of the HD DVD and the like. Additionally, as for the medium, in a write once medium, since the bias power influences the performance thereof, it has been required to consider adjustment thereof. That is, the conventional techniques cannot be directly applied to the HD DVD and the like.
Because of such situations, in a high density system using the PRML such as the HD DVD, it becomes a substantially-major problem on development of the high density optical disc to define in a high density system using the PRML such as the HD DVD: how to adjust the recording strategy; and the order of adjustments of recording strategy parameters.
A purpose of a present invention is to provide a technique that is widely applicable for a recording and reproducing device of a high density optical disc and a recording strategy adjustment method to improve the reliability of the recording and reproducing device.
A recording strategy for specifying an output waveform of a laser beam irradiated to a recording layer of an information recording medium is adjusted by the following recording strategy adjustment method. The recording strategy adjustment method includes: a base strategy determination step of determining a basic recording strategy; a first top pulse width set step of specifying a shortest mark in a pattern string formed on a recording layer of the information recording medium after the base strategy determination step, and setting a width of a top pulse being a pulse for recording the shortest mark; and a recording power adjustment step of adjusting a recording power including a record power and a bias power.
It is possible to enhance reliability of a recording and reproducing device according to the present invention as a recording and reproducing device of a high density optical disc and a recording strategy adjustment method.
Some purposes, effects, and features of an above-mentioned invention will be further clear from descriptions of exemplary embodiments in coordination with accompanying drawings, in which:
Referring to drawings, some exemplary embodiments of the present invention will be explained. However, the exemplary embodiments do not limit the technical scope of the present invention.
Meanwhile, the exemplary embodiment described below will be explained, assuming that the optical disc 14 is a medium accepting a standard of the HD DVD and is a recordable medium writable once (For example, the HD D)VD-R). Additionally, in the exemplary embodiment described below, a case where a physical format of the optical disc 14 is an in-groove format having a bit pitch of 0.15 μm, a track pitch of 0.40 μm will be exemplified.
The optical disc 14 such as the HD DVD is a type of media called as the Low-to-High medium whose reflectivity increases by recording. In the optical disc 14, a guide groove called a pregroove is formed on a discoidal transparent substrate having a thickness of 0.6 mm and a diameter of 12 cm, the substrate being made of polycarbonate. In recording and reproducing information, a laser light of the information recording and reproducing device 1 (an optical disc drive) can scan the disc along this guide groove. The information recording and reproducing device 1 records a pattern string to a recording layer formed on the substrate.
The optical head 3 has a configuration which includes a beam-receiving part 11. The beam-receiving part 11 has a function for: reflecting a beam from the laser diode 8 to an objective lens; and passing a reflected beam from the optical disc 14 to a beam splitter 12. A recording strategy adjuster 13 for controlling adjustment of a recording strategy, a record power, and a bias power is incorporated inside the system controller 6.
The beam splitter 12 reflects a beam from the laser diode (LD) 8 to the objective lens. In addition, the beam splitter 12 passes a reflected beam from the optical disc 14 to the beam-receiving part 11. The beam-receiving part 11 converts the beam into an electric signal to supply the signal to a PreAMP not shown in the drawing. The PreAMP amplifies the received electric signal and supplies the signal to a RF circuit part 4.
The RF circuit 4 calculates the PRSNR, an amplitude, and a modulation degree. A signal from the beam splitter 12 is inputted to the RF circuit 4, and is processed by the filtering, the equalizing, the PLL, and the like. In a case of using the PRML, a process such as the Viterbi decoding is carried out here. To facilitate understanding of a present invention, an exemplary embodiment described below will be explained in accordance with a case where the LD wavelength of the optical head 3 is 405 nm and the NA (numerical aperture) is 0.65.
The recording strategy adjuster 13 of the system controller 6 recognizes a correspondence between a recording condition and a signal quality on: the basis of the PRSNR sent from the RF circuit 4; and a PI error obtained from a data string demodulated by the demodulator 5 (amplitude depending on circumstances), and adjust an optimum recording strategy by controlling a series of adjustment sequence.
A configuration of the RF circuit 4 will be explained below.
In the RF circuit 4, an adaptively-equalized signal and a Viterbi-decoded data string signal are inputted to a signal comparator, and the PRSNR is calculated by the signal comparator. A noise of each time required at the PRSNR calculation is calculated as a difference of an ideal signal waveform obtained by a convolution integral of the Viterbi-decoded data string signal and the (1, 2, 2, 2, 1) vector; and the adaptively-equalized signal (an actual signal waveform). In addition, an amplitude and a modulation degree are calculated by using a difference between the ideal signal waveform and the adaptively-equalized signal (an actual signal waveform) in the PRSNR detector.
A configuration of the above-mentioned asymmetry corrector 24 will be explained below.
An operation of this exemplary embodiment will be explained below. Here, 2 T serves as a single pulse, and this single pulse is referred to as a top pulse.
Referring to
Next, at step S102, a top pulse width corresponding to the shortest mark is determined on the basis of the basic pulse width obtained at step S101 by using the PRSNR. Regarding the pulse width at this time, the top pulse width is determined by changing “the basic pulse+(approx. −0.06 T to +0.18 T)” in steps of approx. 0.03 T, employing the basic pulse width as a center.
At step S103, each of the record power and the bias power is determined in turn by: changing a range of approx. ±20% in steps of 5%; and using the PRSNR, employing the initially-predetermined power as a center.
In addition, a case where an edge to be changed is a posterior edge of pulse always in any pulses will be explained below. In this case, at step S101 of
Next, at step S102, regarding the top pulse width corresponding to the shortest mark, the top pulse width is determined on the basis of the basic pulse width obtained at step S101 by changing “the basic pulse+(approx. −0.06 T to +0.18 T)” in steps of approx. 0.03 T, employing the basic pulse width as a center.
Next, at step S103, each of the record power and the bias power is determined in turn by changing a range of approx. ±20% in steps of 5%, employing a predetermined power as a center. An adjustment result of a fifth exemplary embodiment is the same as the result of
A second exemplary embodiment of a present invention will be explained below. A configuration of the information recording and reproducing device 1 of a second exemplary embodiment is the same as that of the first exemplary embodiment. Accordingly, a detailed explanation of the configuration of the information recording and reproducing device 1 will be omitted in a second exemplary embodiment. In the information recording and reproducing device 1 of a second exemplary embodiment, an operation of the recording strategy adjuster 13 is different from that of the first exemplary embodiment.
Since the shortest mark has 2 T (the longest has 13 T) in a case of ETM modulation, marks having 3 T or more are included in that. In a second exemplary embodiment, an adjustment is carried out by separating 3 T and 4 T or more in separated categories, and all of the marks of 4 T or more are assumed to have a same top pulse width. Here, an adjustment order is from 3 T to 4 T or more, and the top pulse width is determined in turn in the order from the top pulse width corresponding to the mark of 3 T to the top pulse width corresponding to the mark of 4 T or more on the basis of the basic pulse width obtained at step S101. Regarding the pulse width at this time, the top pulse width is determined by changing “the basic pulse+(approx. −0.06 T to +0.18 T)” in steps of approx. 0.03 T to change an anterior edge of pulse, employing the basic pulse width as a center and employing the PRSNR as an index.
A third exemplary embodiment of a present invention will be explained below. A configuration of the information recording and reproducing device 1 of a third exemplary embodiment is the same as that of the first exemplary embodiment. Accordingly, a detailed explanation of the configuration of the information recording and reproducing device 1 will be omitted in a third exemplary embodiment. In the information recording and reproducing device 1 of a third exemplary embodiment, an operation of the recording strategy adjuster 13 is different from that of the first exemplary embodiment. In a third exemplary embodiment, the recording strategy adjuster 13 sets a width of last pulse for recording a mark.
At step S105, among the last pulses for mark formation on the information recording medium, a width of last pulse for recording a mark of any length longer than the shortest mark by one recording unit length (1 T) or more is changed. In this manner, the width of last pulse for recording a mark is appropriately set. Meanwhile, in the case of the (k-1)-type pulse train, 2 T includes only the top pulse. Accordingly, an edge opposite to the edge of pulse used for the adjustment at step S102 may be adjusted at this step S105.
In a third exemplary embodiment, as the order of adjustment, a posterior end of the shortest mark is adjusted, a posterior end of the last pulse of 3 T is adjusted, and then a posterior end of the last pulse of 4 T or more is adjusted. In addition, similar to the second exemplary embodiment, an adjustment in a third exemplary embodiment is carried out by separating 3 T and 4 T or more in separated categories. Here, all of the marks of 4 T or more are assumed to have a same last pulse width. In the adjustment in a third exemplary embodiment, the last pulse width is determined in turn in the order from the last pulse widths corresponding to 2 T mark and 3 T mark to the last pulse width corresponding to 4 T or more on the basis of the basic pulse width obtained at step S101. Regarding the pulse width at this time, the last pulse width is determined by changing “the basic pulse+(approx. −0.16 T to +0.18 T)” in steps of approx. 0.03 T, employing the basic pulse width as a center Meanwhile, in the case of the (k)-type pulse train, the width of last pulse is employed also in 2 T, and when the width is applied to this exemplary embodiment, a posterior end of last pulse is adjusted.
Improvement of the fifth medium cannot be obtained in the second exemplary embodiment. However, referring to
The device may be configured so as to selectively determine as to which one of the first to third exemplary embodiments is carried out on the basis of balance between a restriction of time required for the adjustment and an adjustment accuracy. In addition, it may be determined at a design phase which one of the first to third exemplary embodiments is carried out. The third exemplary embodiment can be carried out when the adjustment order at step S105 is changed. Moreover, it is also possible not to carry out an adjustment of either one of the adjustments of: the posterior end of last pulse of 3 T; and the posterior end of last pulse of 4 T or more. Furthermore, it is also possible to carry out the adjustment after further subdividing the category of 4 T or more. Additionally, the process shown at step S105 may be carried out prior to the operation at step S104 or before. And further, Step S105 may be carried out after the process at step S103 without carrying out the process at step S104. It is preferred that the information recording and reproducing device 1 is configured so as to selectively carry out these operations on the basis of balance between a restriction of time required for the adjustment and an adjustment accuracy. In addition, in the information recording and reproducing device 1, these operations may be determined at a design phase on the basis of balance between a restriction of time required for the adjustment and an adjustment accuracy.
A fourth exemplary embodiment of a present invention will be explained below. A configuration of the information recording and reproducing device 1 of a fourth exemplary embodiment is the same as that of the first exemplary embodiment. Accordingly, a detailed explanation of the configuration of the information recording and reproducing device 1 will be omitted in a fourth exemplary embodiment. In a fourth exemplary embodiment, an operation of the recording strategy adjuster 13 is different from that of the first exemplary embodiment. The information recording and reproducing device 1 of a fourth exemplary embodiment includes a power allowance judgment function for judging whether or not a recording power has been adjusted to be a power or less that can be emitted by the information recording and reproducing device 1. The information recording and reproducing device 1 judges whether or not the recording power has been adjusted to be a power or less that can be emitted. As a result of the judgment, in a case where the recording power is near an emission limit, the adjustment at step S106 described later is carried out immediately before an end of the adjustment.
a) is a table (hereinafter referred to as the table 44) referred to in a process carried out at the all pulse widths uniform adjustment step. The table 44 exemplifies a correspondence relationship between a record power and an amount of change of pulse width. For example, in a device having the maximum emission limit of 12 mW, when a power margin of at least ±10% is secured, an allowable value is 10.8 mW. In a case of a record power exceeding this, step S106 is carried out on the basis of the table 44. Meanwhile, a reduction rate of record power is obtained by the following expression (1).
(Obtained record power)×Reduction rate≦10.8 mW (in the maximum emission of 12 mW) (1)
In a case where a record power is 11 mW when an optical disc 14 is inserted into the information recording and reproducing device 1 and a recording condition is adjusted, the record power exceeds 10.8 mW that is the record power of an allowable value. Accordingly, the information recording and reproducing device 1 executes recording and a reproducing at an adjusted value obtained by reducing the record power of 11 mW by 5% and increasing a conversion magnification of pulse width by 5%, using the table 44 and without changing the bias power.
As a result obtained by measuring the execution result regarding the PRSNR, the PRSNR is approximately 24. Meanwhile, in a case expression (1) is not satisfied, the reduction rate is reduced by 5, 10, 15, and 20 in turn (refer to the table 45 of
A fifth exemplary embodiment of a present invention will be explained below. A configuration of the information recording and reproducing device 1 in a fifth exemplary embodiment is the same as that of the first exemplary embodiment. Accordingly, a detailed explanation of the configuration of the information recording and reproducing device 1 will be omitted in a fifth exemplary embodiment. Additionally, in a fifth exemplary embodiment, an operation of a case where the target optical disc 14 has a system information area and “Disc Manufacturing information” including information such as a disc maker name and a manufacturing area is retained will be exemplified. In this case, when an optical disc 14 is inserted, the optical head 3 of the information recording and reproducing device 1 moves to the system information region of the disc. The optical head 3 obtains a type of the disc, a disc maker name, and the like from the system information region on the basis of the “Disc Manufacturing information” including information such as the disc maker name and a manufacturing area. The information recording and reproducing device 1 determines the inserted optical disc 14 as a medium A on the basis of the obtained information.
The information recording and reproducing device 1 of a fifth exemplary embodiment is different from that of the first exemplary embodiment in an operation of the recording strategy adjuster 13. Specifically, at step S102, a width obtained by multiplying a coefficient preliminarily determined as a top pulse width corresponding to the shortest mark by the basic pulse width is set as a top pulse width. Then, the top pulse widths of 2 T, 3 T, and 4 T or more corresponding to the basic pulse width, corresponding information of the last pulse width, and a performance obtained by preliminarily matching performances in a drive device (supposed PRSNR) are obtained.
After determining the inserted optical disc 14 as the medium A, the information recording and reproducing device 1 obtains the table 46. After that, the information recording and reproducing device 1 carries out the adjustment in accordance with the recording adjustment method shown in
The PRSNR of a case where a region of the above-mentioned medium A to which the adjustment of the fifth exemplary embodiment is completed is reproduced is 22.5. Referring to
Additionally, the top pulse width is set at step S102, however, a top pulse width other than 2 T may be set independently or simultaneously as the top pulse width setting. Moreover, in a case where the supposed PRSNR is not satisfied, a top pulse width other than 2 T may be set independently in turn or simultaneously. Furthermore, in the case where the supposed PRSNR is not satisfied, step S102 may be searched again as shown in the first exemplary embodiment.
In addition, compared to the first exemplary embodiment, the case of the first exemplary embodiment is a method efficient in that: the recording strategy can be adjusted even when a medium that was not appeared at shipment of drive is used for the drive device; and the method has a high accuracy and can be widely used. This exemplary embodiment is preferred to be applied to a medium to which parameters are preliminarily matched. Even in a case of a medium whose information is not retained by a drive, the adjustment can be simply carried out.
A sixth exemplary embodiment of a present invention will be explained below. A configuration of the information recording and reproducing device 1 in a sixth exemplary embodiment is the same as that of the first exemplary embodiment. Accordingly, a detailed explanation of the configuration of the information recording and reproducing device 1 will be omitted in a sixth exemplary embodiment. Unlike the first exemplary embodiment, a sixth exemplary embodiment carries out an adjustment by using an overall amplitude of a reproduction signal including marks having various lengths and spaces as a performance index for the determination of the base strategy at step S101. Meanwhile, when a pulse width is changed, an anterior edge of the pulse width is assumed to be changed in any pulses. In addition, the following explanation is given corresponding to a case where the optical disc 14 to be adjusted (for example, HD DVD) is the second medium shown in
The operation of a sixth exemplary embodiment starts when the optical disc 14 is set to the information recording and reproducing device 1. At step S101, the maximum power of a record power that can be emitted of the information recording and reproducing device 1 is 12 mW, the record power is 9.0 mW and the bias power is 3.6 mW as predetermined powers in consideration of an average power margin of many media used for study, temporal changes, environmental changes, and the like.
In addition, the record power and the bias power are fixed, and the basic pulse width is determined, employing the same pulse width for all of the top pulse, the middle pulse, and the last pulse. On this occasion, the basic pulse width is obtained by: changing the basic pulse width from 0.38 T to 0.86 T in step widths of 0.03 T; and using the all over amplitude to determine the base strategy. In this case, it is supposed that a pulse width where a change rate of peak value of amplitude of a maximum mark space length is approximately constant to a pulse width increase is selected. In a sixth exemplary embodiment, a result showing the basic pulse width is 0.59 T is obtained as a result of carrying out the process at step S101 to the optical disc 14.
Next, at step S102, atop pulse width corresponding to the shortest mark is determined on the basis of the basic pulse width of 0.59 T obtained at S101 by using the PRSNR. Regarding the pulse width at this time, the top pulse width is determined by changing “the basic pulse+(approx. −0.06 T to +0.18 T)” in steps of approx. 0.03 T, employing the basic pulse width as a center. In a sixth exemplary embodiment, the 2 T top pulse width is obtained as 0.75 T as a result of carrying out the process at step S102 to the optical disc 14.
Next, at step S103, each of the record power and the bias power is changed within approx. ±20% in steps of 5%, employing an initially-predetermined power as a center, and powers are determined in turn by using the PRSNR. In a sixth exemplary embodiment, as the result of carrying out the process at step S103 to the optical disc 14, the PRSNR is approximately 27 as a final performance. This is the same result as that of the second medium in
A seventh exemplary embodiment of a present invention will be explained below. A configuration of the information recording and reproducing device 1 in a seventh exemplary embodiment is the same as that of the first exemplary embodiment. Accordingly, a detailed explanation of the configuration of the information recording and reproducing device 1 will be omitted in a seventh exemplary embodiment. Additionally, in a seventh exemplary embodiment, the following explanation is given corresponding to a case where the optical disc 14 to be adjusted (for example, HD DVD) is a seventh medium shown in
At step S101, when the maximum power of a record power that can be emitted of the information recording and reproducing device 1 is 12 mW, the record power is 7.0 mW and the bias power is 3.0 mW as predetermined powers in consideration of a power margin of the optical disc 14, temporal changes, environmental changes, and additionally an temperature increase. In addition, the basic pulse width is obtained by: changing the basic pulse width from 0.38 T to 0.86 T in step widths of 0.03 T; and using the PRSNR, employing the same pulse width for all of the top pulse, the middle pulse, and the last pulse with the record power and the bias power fixed, and the base strategy is determined. On this occasion, in a case where a basic pulse width showing the best cannot be determined, the record power is 7.7 mW by increasing at 10%. Then, a step width is set to be wider than before (for example, 0.06 T), and a provisional basic pulse width is obtained by using the PRSNR. On that basis, the basic pulse width is finally determined by using the PRSNR through the recording and reproducing at a pulse width of ±0.03 T, employing a pulse width showing the best PRSNR as a center.
Next, each of the record power and the bias power is changed within approx. ±20% in steps of 5%, employing an initially-predetermined power as a center, and powers are determined in turn by using the PRSNR (step S201). Then, a top pulse width corresponding to the shortest mark is determined on the basis of the basic pulse width obtained at step S101 by using the PRSNR. Regarding the pulse width at this time, the top pulse width is determined by changing “the basic pulse+(approx. −0.06 T to +0.18 T)” in steps of approx. 0.03 T, employing the basic pulse width as a center.
In a seventh exemplary embodiment, the base strategy can be certainly determined by appropriately changing a way to set the power and the pulse width depending on the situation. As a result of the adjustment, the PRSNR is approximately 29 and a performance nearly equal to a seventh medium of
An eighth exemplary embodiment of a present invention will be explained below A configuration of the information recording and reproducing device 1 in an eighth exemplary embodiment is the same as that of the first exemplary embodiment. Accordingly, a detailed explanation of the configuration of the information recording and reproducing device 1 will be omitted in an eighth exemplary embodiment Additionally, in an eighth exemplary embodiment, the following explanation is given corresponding to a case where the optical disc 14 to be adjusted (for example, HD DVD) in the second medium shown in
Unlike the first exemplary embodiment, an eighth exemplary embodiment carries out the selection of base strategy by: fixing a bias power to be a predetermined power with a pulse width constant; and changing a record power.
An eighth exemplary embodiment will be explained in response to a case where a maximum power of a record power that can be emitted of the information recording and reproducing device 1 is 12 mW. In consideration of a power margin of the optical disc 14, temporal changes, environmental changes, and the like, the record power as predetermined powers is changed within approx. ±20% in steps of 5%, employing 9.0 mW as a center. In addition, the bias power is fixed to 3.6 mW. All of the top pulse, the middle pulse, and the last pulse are set to 0.59 T (the same pulse width), and the base strategy is determined by using the PRSNR. Meanwhile, the pulse width set here is preliminarily studied, however, the pulse width may be an average value in a device to be used and a plurality of media. In an eighth exemplary embodiment, it has been found as a result that the best record power is 9.4 mW in the case where the maximum power is 12 mW.
Next, at step S102, the top pulse width corresponding to the shortest mark is determined on the basis of the basic pulse width by using the PRSNR. Regarding the pulse width at this time, the top pulse width is determined by changing “the basic pulse+(approx. −0.06 T to +0.18 T)” in steps of approx. 0.03 T at an anterior edge of pulse, employing the basic pulse width as a center. In a case where the obtained record power is 9.4 mW, the bias power is 3.6 mW, the basic pulse width is 0.59 T, 2 T top pulse width is determined to be 0.75 T as a result.
Next, at step S103, each of the record power and the bias power is changed within approx. ±10% in steps of 36, employing an initially-predetermined power as a center, and powers are determined in turn by using the PRSNR. The final performance of the PRSNR is approximately 27. This is nearly equal to the result of the second medium in
A ninth exemplary embodiment of a present invention will be explained below. A configuration of the information recording and reproducing device 1 in a ninth exemplary embodiment is the same as that of the first exemplary embodiment. Accordingly, a detailed explanation of the configuration of the information recording and reproducing device 1 will be omitted. In a ninth exemplary embodiment, the adjustment is carried out in a procedure similar to that of the third exemplary embodiment. Here, unlike the third exemplary embodiment, the adjustment is carried put by using the (k)-type pulse train in a ninth exemplary embodiment. In addition, an anterior edge of pulse is changed in the adjustment of the top pulse, and a posterior edge of pulse is changed in the adjustment of the last pulse.
In a ninth exemplary embodiment, each of steps S104 and S105 of the procedure shown in
At step S101, when a maximum power of a record power that can be emitted of the information recording and reproducing device 1 is 12 mW, the record power is 9.0 mW and the bias power is 3.6 mW as predetermined powers in consideration of a power margin of the optical disc 14, temporal changes, environmental changes, and the like. The PRML detection is carried out in determining this base strategy by employing the asymmetry corrector 24, and the PRSNR is measured. In the determination of base strategy, a basic pulse width is obtained by changing the basic pulse width from 0.38 T to 0.86 T in step widths of 0.03 T; and using the PRSNR, employing the same pulse width for all of the top pulse, the middle pulse, and the last pulse, and the base strategy is determined.
Next, the top pulse width corresponding to the shortest mark is determined on the basis of the basic pulse width obtained at step S101 by using the PRSNR. Regarding the pulse width at this time, the top pulse width is determined by changing “the basic pulse+(approx. −0.06 T to +0.18 T)” in steps of approx. 0.03 T, employing the basic pulse width as a center.
Next, each of the record power and the bias power is changed within approx. ±20% in steps of 5%, employing an initially-predetermined power as a center, and powers are determined in turn by using the PRSNR (step S103). At step S104, an adjustment is carried out by separating 3 T and 4 T or more in separated categories, and all of the marks of 4 T or more are assumed to have the same top pulse. The top pulse width is determined in turn in the order from the top pulse width corresponding to the mark of 3 T to the top pulse width corresponding to the mark of 4 T or more on the basis of the basic pulse width obtained as step S101. Regarding the pulse width at this time, the top pulse width is determined by changing “the basic pulse+(approx. −0.06 T to +0.18 T)” in steps of approx. 0.03 T to change an anterior edge of pulse, employing the basic pulse width as a center and employing the PRSNR as an index.
At step S105, an adjustment is carried out by separating 2 T, 3 T, and 4 T or more in separated categories, and all of the last pulse widths of 4 T or more are assumed to have the same top pulse. In the adjustment, the top pulse widths are determined in turn in the order from the last pulse width corresponding to the mark of 2 T, the last pulse width corresponding to the mark of 3 T, and the last pulse width corresponding to the mark of 4 T or more on the basis of the basic pulse width obtained as step S101. Regarding the pulse width at this time, the last pulse width is determined by changing “the basic pulse+(approx. −0.06 T to +0.18 T)” in steps of approx. 0.03 T to change an posterior edge of pulse, employing the basic pulse width as a center.
A performance under the final recording condition is approximately 22 in the PRSNR, and also in the case of using the (k)-type pulse train, a good recording condition can be obtained at a high speed also in the HD DVD using the PRML detection by employing the recording condition adjustment method and the information recording and reproducing device 1 of a present invention.
A tenth exemplary embodiment of a present invention will be explained below. A configuration of the information recording and reproducing device 1 in a tenth exemplary embodiment is the same as that of the first exemplary embodiment. Accordingly, a detailed explanation of the configuration of the information recording and reproducing device 1 will be omitted. In a tenth exemplary embodiment, the adjustment is carried out in a procedure similar to that of the ninth exemplary embodiment.
Unlike the ninth exemplary embodiment, a tenth exemplary embodiment employs not only a multi-pulse but also a non multi-pulse (a strategy based on a rectangular shape) as a recording strategy.
In the tenth exemplary embodiment, similar to the procedure of
At step S101, the maximum power of a record power that can be emitted of the information recording and reproducing device 1 is 12 mW, the record power P1 is 9.0 mW and the bias power P2 is 3.6 mW as predetermined powers in consideration of a power margin of many media used for study, temporal changes, environmental changes, and the like, a basic pulse width of 0.59 T obtained in many average media is set as the top pulse width and the last pulse width, a range of ±20% is changed in steps of 5%, employing the middle power P3 of 4.5 mW as a center that is approximately half of the record power P1=9.0 mW, and the middle power is selected to determined a base strategy. The PRML detection is carried out by employing the asymmetry corrector 24 only in determining this base strategy, and the PRSNR is measured. The middle power of 5.2 mW has been obtained.
Next, the top pulse width corresponding to the shortest mark is determined by using the PRSNR on the basis of the P1 of 9.0 mW as a predetermined power, the middle power P3 of 5.2 mW obtained at step S101, and the basic pulse width of 0.59 T. Regarding the pulse width at this time, the top pulse width is determined by changing “the basic pulse+(approx. −0.06 T to +0.18 T)” in steps of approx. 0.03 T, employing the basic pulse width as a center (step S102).
And next, each of the record power and the bias power is changed within approx. ±20% in steps of 5%, keeping the ratio centered in the middle power obtained as the predetermined power P1=9.0 mW, and powers are determined in turn by using the PRSNR (step S103).
At step S104, an adjustment is carried out by separating 3 T and 4 T or more in separated categories, and all of the marks of 4 T or more are assumed to have the same top pulse. Here, the top pulse width is determined in turn in the order from the top pulse width corresponding to the mark of 3 T to the top pulse width corresponding to the mark of 4 T or more on the basis of the basic pulse width obtained as step S101. Regarding the pulse width at this time, the top pulse width is determined by changing “the basic pulse+(approx. −0.06 T to +0.18 T)” in steps of approx. 0.03 T to change an anterior edge of pulse, employing the basic pulse width as a center and employing the PRSNR as an index.
At step S105, an adjustment is carried out by separating 2 T, 3 T, and 4 T or more in separated categories, and all of the last pulse widths of 4 T or more are assumed to have a same pulse width. In the adjustment, the top pulse widths are determined in turn in the order from the last pulse width corresponding to the mark of 2 T, the last pulse width corresponding to the mark of 3 T, and the last pulse width corresponding to the mark of 4 T or more on the basis of the basic pulse width obtained as step S101. Regarding the pulse width at this time, the last pulse width is determined by changing “the basic pulse+(approx. −0.06 T to +0.18 T)” in steps of approx. 0.03 T to change a posterior edge of pulse, employing the basic pulse width as a center.
In the case of a tenth exemplary embodiment, a frame is determined by not the multi-pulse but the Pm (middle power; P3 in the rectangle of
In a plurality of the above-mentioned exemplary embodiments, the explanations have been given in response to the case where the LD wavelength of the optical head 3 is 405 nm and the NA (numerical aperture) is 0.65. The present invention is not restricted to these values, and can be applied to various wavelengths and the various NAs. In addition, a class called PR(12221) is used in the above-mentioned exemplary embodiments, however, when another class such as PR(1221) is used, a present invention can be applied. Moreover, in the above-mentioned exemplary embodiments, it is supposed that the ETM employed in the HD DVD is used as a modulation code, however, when another modulation code is used, a present invention can be applied. In that case, a shortest data length of, for example, kT (k is a natural number of 3 or more) may be changed. Furthermore, the HD DVD is used in the above-mentioned exemplary embodiments, however, the Blu-ray Disc (BD disc) can be used.
As shown in a plurality of above-mentioned exemplary embodiments, the record power and the pulse width are parameters that influence each other. Accordingly, when the adjustment starts with either one of them randomly fixed, the adjustment may easily fall into a local minimum (a local optimum). For this reason, in a plurality of the above-mentioned exemplary embodiments, the recording strategy adjustment is carried out by classifying the recording strategy into three categories of the record power, the multi-pulse width (a representative of a long mark), and the top pulse width accepting the shortest mark. Here, the multi-pulse shows a pulse other than the top pulse. In the case of a longer mark, almost of the marks are formed of the multi-pulse. When the multi-pulse width is selected as a category, the recording strategy adjustment can be carried out to the mark having longer multi-pulse width as a representative value.
An adjustment result of a case where the adjustment is carried out by changing the order of each category when the adjustment is carried out by classifying the recording strategy into three categories will be explained below as a comparative example. In the present comparative example, the adjustment is carried out by using the above-mentioned information recording and reproducing device 1. In addition, the write once optical disc 14 (for example, the HD DVD-R) that is recordable once is used as the information recording medium. The optical disc 14 is a type of medium that uses organic coloring material accepting a short wavelength to a recording layer and that increases reflectivity after a recording, and is a type of optical disc 14 called a Low-to-High medium. As a physical structure of the disc, a guide groove called a pregroove is formed on a discoidal transparent substrate having a thickness of 0.6 mm and a diameter of 12 cm, the substrate being made of polycarbonate, and in recording and reproducing information, laser light of the information recording and reproducing device 1 (an optical disc drive) can scan the disc along this guide groove. A film for the recording is formed on this substrate. As a physical format, an in-groove format having a bit pitch of 0.15 μm and a track pitch of 0.40 μm is used.
A procedure A execution result shows an execution result of the recording strategy adjustment of a case where “record power fixation multi-pulse width search the shortest mark correspondence top pulse width search” is the procedure A. A procedure B execution result shows an execution result of the recording strategy adjustment of a case where “record power fixation the shortest mark correspondence top pulse width search multi-pulse width search” is the procedure B. A procedure C execution result shows an execution result of the recording strategy adjustment of a case where “multi-pulse width fixation record power search the shortest mark correspondence top pulse width search” is the procedure C. A procedure D execution result shows an execution result of the recording strategy adjustment of a case where “multi-pulse width fixation the shortest mark correspondence top pulse width search record power search” is the procedure D.
In addition, the (k-1)-type pulse train is used as a condition for obtaining the execution result shown in
Referring to
A fact that a combination of the multi-pulse and the record power has to be firstly adjusted means that an overview of the recording marks, namely, a frame has to be firstly determined. In other words, it can be said that sizes of recording marks with various lengths are determined by the combination of the multi-pulse and the record power. On the contrary, when the combination is inappropriate, the adjustment may fall into a local minimum. In addition, the top pulse of the shortest mark is an important parameter that influences a recording and reproducing performance. However, based on a viewpoint of the recording strategy adjustment, the top pulse of the shortest mark is a somewhat attendant element. At the same time, regarding the marks with various lengths, the top pulse is a somewhat attendant element from a viewpoint of the recording strategy adjustment.
In addition, regarding a plurality of the optical discs 14 applicable to the above-mentioned exemplary embodiments, there is a plurality of parameter configurations (combinations) showing a nearly equal performance.
Moreover,
In a case where the pulse width is broad, a size of the recording mark is ensured (formed) even when the power is not sufficiently high. As the result, the mark is formed before reaching a sufficient temperature to form the mark, resulting in formation of an unstable mark. In a case where the pulse width is slim, it is required to set the power high to ensure a size of mark to be formed. When the power is high, the temperature substantially exceeds a temperature required for the mark formation, and thereby a stable mark can be formed.
In the optical information recording and reproducing device 1, an upper limit is provided to an emission output of laser used for the recording. In this case, the information recording and reproducing device 1 has to maximize a performance of medium under the limit of emission output. When a power range and a pulse width to be intensively searched are determined for an optimum record power, it is preferred to adjust the basic pulse width to be narrow (slim); and the record power to be high.
Referring to
Here, a result of the case where the adjustment of the recording power at step S103 is carried out at a time when the base strategy is determined prior to the adjustment of 2 T top at step S102 as described in the above-mentioned seventh exemplary embodiment is shown in
Accordingly, it is found that the recording power may be interchangeable in the adjustment method of strategy as in the seventh exemplary embodiment. Additionally, the adjustment of the recording power here (step S103) is considered as a fine adjustment of strategy based on a frame. Moreover, a setting step of the pulse width is restricted in the device. In contrast, since the power can be set at more fine setting steps, the power can be said to be suitable for the fine adjustment.
In addition, the information recording and reproducing device 1 can identify a maker name by using an ID retained in a medium. Accordingly, a recording condition parameter in the device can be preliminarily related to a maker of a medium. When the adjustment is carried out by setting a width of a top pulse corresponding to the shortest mark to be approximately 1.2 times as broad as the basic pulse after the basic pulse width is specified by the adjustment and a frame is determined on the basis of the correspondence relationship, the adjustment can be carried out at higher speed.
A person skilled in the art is able to easily carry out various modifications of the above-mentioned exemplary embodiments. Accordingly, the present invention is not limited to the above-mentioned exemplary embodiments, and is interpreted within the broadest scope considered on the basis of the claims and equivalents.
This application claims the priority based on Japanese Patent Application No. 2007-11318 filed on Jan. 22, 2007, and the disclosures of Japanese Patent Application No. 2007-11318 are hereby incorporated by reference.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2007-011318 | Jan 2007 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2008/050580 | 1/18/2008 | WO | 00 | 8/4/2009 |
