Patent Application
20080151710
The present invention relates to an optical disk apparatus for recording data onto a disc-like information recording medium, such as, an optical disk, and in particular, it relates to an optical disk apparatus adjusting the recording power of a laser beam, optimally, and also a method for determining the recording power for the same.
Conventionally, when recording data on an optical disk, for the purpose of obtaining sufficient recording quality for each of optical disks, an optimum recording power of the laser beam is obtained by executing a test recording thereon, and then recoding is conducted on the data with that optimum recording power obtained. Hereinafter, such a step is called by “OPC (Optimum Power Control)”. In that instance, according to the conventional technology, various kinds of methods are implemented and/or proposed, as parameters for estimating the recording quality. For example, for CD and/or DVD disks, there is applied a method of using asymmetry of signals recorded (“β” value) as an estimation index thereof (i.e., a “β” method). Also for the Blu-ray disk (“BD”) of high density and large capacity, so-called a “κ” method is recommended, i.e., a method for obtaining the optimum value through linear approximation of changes, with using modulation factor, as the estimation index thereof (in more details, the “κ” method is recommended for BD-RE, while the “κ” method or the “β” method for BD-R). However, parameters for determining the recording condition under each of those conditions are stored in a portion thereof, for each of the optical disks, in the form of control data, for example.
Through improvement of those methods, there is proposed a method, for determining the optimum condition at high accuracy. For example, in the following Patent Document 1 is disclosed a method for determining the recording power upon basis of a value relating to reflectivity and the “β” value, which are obtained from the optical disk, as an improvement of the “β” method. Also, in the following Patent Document 2 is disclosed a method, as an improvement of the “κ” method, obtaining the optimum value from measurement results within a region centering around a target power level, by conducting the measurement two (2) times upon the modulation factor.
Further, upon high-speed recording on the optical disk, mainly, there is applied a recording method of increasing the recording velocity directing from an inner periphery to an outer periphery thereof, being so-called a CAV (Constant Angular Velocity), and a laser power and strategy, for conducting the recording on an optical disk, can be obtained by adding compensation, which is obtained through calculation, to the optimum value, which is obtained through the test recording or writing within a region located between the inner periphery and the outer periphery of the disk.
For example, in the following Patent Document 3 is described a method of using the inner periphery test writing and the outer periphery test writing for the CAV recording, and with this method, as is shown in
On the other hand, it is also necessary to add an ill influence upon recording due to unevenness of sensitivity within each of the optical disks, and/or an ill influence upon recording due to changes of the laser characteristics caused by changes of an ambient temperature thereof, and ordinarily, there is applied a method of confirming the recording quality during the recording, being called “walking OPC”, in particular, for the DVD. This is that, for example, as is shown in
By the way, in particular, for the disk having high density and large capacity, such as, the BD mentioned above, for example, it is required to determine the optimum power, more accurately or minutely.
However, to such the requirement, with the conventional “β” method mentioned above, though it is an easy method for estimating the recording quality, but it is inferior in the sensitivity of measurement in the vicinity of the optimum recording power (i.e., change of the “β” value is small to the value of recording power); therefore, it is difficult to achieve the measurement with high accuracy. Also, with the “κ” method according to the conventional technology, since the power is low in the vicinity of the linear approximation, then the accuracy of measurement is lowered down, i.e., the optimum values, which are obtained for the recording power, vary widely.
Further, with the method described in the Patent Document 1 mentioned above, there is necessity of a technology for measuring the values relating to the reflectivity, newly, and also with the method described in the Patent Document 2 mentioned above, there is a drawback that measurement must be conducted two (2) times for the “β” value.
Also, the method described in the Patent Document 3 mentioned above is weak against changes of temperature accompanying the changes of laser characteristics, and further, because of the linear approximation, an error is relatively large. Therefore, it is impossible to determine the optimum recording power with accuracy with respect to the disk having high density and large capacity, such as, the BD disk. Also, with the method described in the Patent Document 4 mentioned above, because of inferior sensitivity of “β” to the recording power in the vicinity of the optimum recording power, for the BD disks mentioned above, in particular, a part of the disks, being called “BD-R (writable only once)” and almost of the disks, being called “BD-RE (rewritable)”, there is pointed out a drawback that the present method cannot be applied therein. In addition thereto, for the blu-ray disk, as will be mentioned later, it is difficult to estimate the “β” value through the walking OPC, and therefore, a new method is necessitated for confirming the recording quality during the recording operation.
Then, according to the present invention, an object thereof is to provide a new technology, for determining the optimum recording power while confirming the recording quality during the recording operation, in particular, for the optical disk, of high density and large capacity, such as, the blu-disk, representatively, i.e., being inferior in the sensitivity of measurement in the vicinity of the optimum recording power and constructed with recording areas or regions, which are divided in a large number thereof by a predetermined information recording unit, i.e., RUB unit, and also provided with an area or region in a part of each of the recording areas, for enabling a free recording, having no relation with the recording of information.
However, before mentioning the present invention, in Japanese Patent Application No. 2005-347484 filed on Dec. 1, 2005, made by the same inventors, etc., it is already confirmed that the “β” sensitivity can be improved by applying a test signal determining an erase power (Pe) to be constant, and there is proposed a method for determining the optimum recording power with using this, and in addition thereto, there is also proposed a method for determining the optimum recording power, in particular, in case of applying the “κ” method adapting the modulation factor M as the index in common with.
And, according to the present invention, applying such the method for determining the optimum recording power, in particular, into the disk of high density and large capacity, such as, the BD disk, for example, and in that instance, as was mentioned above, with using the areas or regions, each being called APC area provided in a part of the recording areas, which are constructed with a large number of regions divided by the predetermined information recording unit (RUB), there is provide a new method for determining the optimum recording power while confirming the recording quality during the recording operation.
In more details, according to the present invention, first of all, there is provided 1. An optical disk apparatus for recording and reproducing data onto/from an optical disk, being constructed with recording regions divided into a plural number thereof, each being made of a predetermined information recording unit, and having a region, into which recording can be made irrespective of information recording, in a part of the recording region, comprising: a signal generator circuit, which is configured to produce a test signal; an optical pickup, which is configured to record the test signal through irradiation of a laser beam onto said optical disk, upon basis of the test signal supplied from said signal generator circuit, and to reproduce said test signal from said disk; a detector circuit, which is configured to obtain a “β” value indicative of asymmetry, from said test signal reproduced by said optical pickup; and a control circuit, which is configured to determine an optimal recording power Pwo from a recording power, a target “β” value of which is the “β” value obtained in said detector circuit, wherein said signal generator circuit produces the test signal, with changing a recording power Pw while fixing an erasing power Pe, and records said test signal into the region formed in a part of the recording regions of said optical disk, into which recording can be made irrespective of said information recording, thereby determining the optimal recording power Pwo for said optical disk.
Also, according to the present invention, also for accomplishing the object mentioned above, there is further provided a method for determining a recording power when recoding data onto an optical disk, being constructed with recording regions divided into a plural number thereof, each being made of a predetermined information recording unit, and having a region, into which recording can be made irrespective of information recording, in a part of the recording region, comprising the following steps of: recording a test signal onto the region, into which recording can be made irrespective of information recording, formed in a part of the recording region, with changing the recording power Pw while fixing the erasing power Pe; obtaining a “β” value indicative of asymmetry, with reproducing said signal recorded; and determining said optimal recording power Pwo from the from a recording power, a target “β” value of which is the “β” value obtained.
Further, according to the present invention, within the optical disk apparatus or the method for determining a recording power when recoding data onto an optical disk, described in the above, preferably, said signal generator circuit produces a second test signal, to make recording in the region formed in a part of the recording regions of said optical disk, into which recording can be made irrespective of said information recording, for determining the erasing power Pe to be used for said test signal, said detector circuit obtains a modulation factor indicative of an amplitude value from said second test signal, which is reproduced from said optical disk; and said signal generator circuit determines the erasing power Pe to be used in said test signal, upon basis of a result of M value of the modulation factor, which is obtained within said detector circuit. Or, preferably, said signal generator circuit determines a value Pe, being the erasing power Pe to be used in said test signal, in accordance with a recording condition recorded in advance on said optical disk, or a recording condition, which is determined by said apparatus in advance for said optical disk, thereby making the recording in the region formed in a part of the recording regions of said optical disk, into which recording can be made irrespective of said information recording, or said signal generator circuit produces the test signal, with using a value of approximately zero (0) as the erasing power Pe to be used in said test signal (Pe0), thereby making the recording in the region formed in a part of the recording regions of said optical disk, into which recording can be made irrespective of said information recording.
Or, according to the present invention, within the optical disk apparatus or the method for determining a recording power when recoding data onto an optical disk, described in the above, preferably, the optimal recording power Pwo for said optical disk is determined by equalizing a plural number of measurement values of the “β” value indicative of asymmetry on a reproduced signal of said test signal, which is recorded into the region formed in a part of the recording regions of said optical disk, into which recording can be made irrespective of said information recording.
Those and other objects, features and advantages of the present invention will become more readily apparent from the following detailed description when taken in conjunction with the accompanying drawings wherein:
a) to 3(c) are views for comparison between the method of the conventional art and the method according to the present invention, in particular, in relation to measurement of “β” value;
a) and 3(b) are views for explaining a measuring method of the “κ” method, which is applied in the present embodiment in common with;
a) and (b) are views for explaining an optimum recording power determining method, according to the embodiment of the present invention;
a) and 14(b) are views for explaining an optimum recording power determining method, according to further other embodiment of the present invention;
Hereinafter, embodiments according to the present invention will be fully explained by referring to the attached drawings. First of all,
In this
On the other hand, a recoding signal generator circuit 6 shown in the figure produces data or test a signal to be recorded, and a laser driver 5 controls a light emission power of the semiconductor laser, upon basis of the data or the test signal from that circuit. As a result of this, at the desired track position on the optical disk can be recorded the data or the test signal mentioned above.
Also, the optical pickup 2 reproduces the recorded data or the recorded test signal mentioned above from the optical disk 1, which is rotationally driven at the predetermined rotation speed. Further, this reproduction signal (i.e., RF signal) is amplified within a RF signal amplifier circuit 7, and demodulated within a data demodulator circuit 8, thereby to be outputted as reproduced data (information).
Further, an OPC information detector circuit 9 in the figure obtains OPC information (quality, such as, the “β” value, etc.) from a result of reproduction of the test signal mentioned above. Also, within a control area or region on the optical disk 1, there is recorded, in advance, a recording condition, including the recording power determination, for that optical disk (hereinafter, “strategy information”), as control data, and it can be used for determining the optimum recording condition through readout thereof.
And, a focus tracking error signal detector 11 detects a level of the reproduction signal (RF signal), for example, and thereby producing focus error and tracking error signals. A focus/tracking controller circuit 12 performs focus control and tracking control of the optical pickup 2, upon basis of those error signals. Also, a system controller (controller circuit) 10 performs controls upon the entire of the apparatus, including the recording power determining steps (OPC) therein, and it stores programs and data for those within a memory 13.
In the structures mentioned above, in particular, mentioning about the determination of the optimum recording power, within the recoding signal generator circuit 6 is reproduced a test signal changing the recording power, etc., in a step-like manner, by referring to the strategy information, and this signal is recorded on trial (i.e., test recording) in the OPC region of the optical disk 1. Next, the test signal is reproduced by the optical pickup 2, so as to make measurement on the qualities of the waveforms reproduced (i.e., the modulation factor and the asymmetry, etc.) within the OPC information detector circuit 9. The system controller (controller circuit) 10 determines the optimum value of the recording power upon basis of the measurement results in relation to the qualities of those reproduction waveforms.
Following to the above, explanation will be given on a method for determining the optimum recording power, according to the present embodiment. Thus,
Also, within the present embodiment, the following indexes are used when estimating the qualities of the reproduction waveforms. A first one is the “β” value indicative of the asymmetry of the reproduction signal, in particular, in positive/negative amplitudes thereof (i.e., the “β” method). Other one is the modulation factor “M” presenting a ratio between amplitude of the reproduction waveform and the maximum (or saturation) amplitude thereof. Conventionally, while determining a target value (“Target”) of the “β” value or the “M” value, the optimum recording power Pwo is determined upon basis of the power Pw, the target value of which can be obtained; however, according to the present embodiment, an improvement is made on this.
Thus, first of all, it is assumed that there is applied the “β” method for estimating the quality upon basis of the “β” value, in order to determine the optimum recording power. However, with the “κ” method applying the modulation factor “M” as the index, since the modulation factor “M” is measured upon the basis of the peak level (an absolute value) of the RF amplitude, then in particular, signals mixing therein from the other layer (already recorded) within the medium of two (2) layers give ill influences upon the modulation factor, in the form of an offset, and it is difficult to escape from this. On the contrary to that, with this “β” method, since the “β” value can be obtained from a ratio between the difference between the peak level and a DC level (a relative value) and the RF amplitude, there no ill influence due to the offset from the other layer. Furthermore, according to the present embodiment, for improving the accuracy thereof, it is characterized in that the erasing power “Pe” of the test signal is fixed.
a) to 3(c) attached herewith are views for comparison between the conventional method and the method according to the present embodiment, in particular, in relation to measurement of this “β” value. First,
On the contrary to this,
However, when determining the value of the optimum value Pwo, it is also possible, not only to shift the value of recording power for obtaining the target value “Target_β” to the optimum value Pwo as it is, but also to obtain the optimum value Pwo by multiplying a predetermined coefficient onto the value of recording power for obtaining the target value “Target_β”, other than that, for example.
Hereinafter, explanation will be made on the details of the steps of the optimum recording power determining method, fixing the erasing power Pe, by referring to a flowchart shown in
<Determination Method 1>
In steps S51 to S54, a preliminary or provisional Pw (Pw′) and or a preliminary or provisional Pe (Pe′) are determined, in accordance with the “κ” method. Thus, in a step S51, under the condition that Pw/Pe=s (already known coefficient, being constant), the test recoding is conducted while changing the Pw and the Pe, thereby measuring the modulation factor “M” (
Next, in steps S55 to S58, the optimum values Pwo and Peo are determined, in accordance with the “β” method. First, in a step S55, recoding of the test signal is conducted with changing the Pe around the Pw′ within a predetermined range n %-m %, while fixing the Pe to the provisional Pe′. In a step S56, the test signal is reproduced, and the OPC information is obtained therefrom, i.e., the “β” value (asymmetry) herein. In a step S57, the optimum value Pwo is determined from such the Pw that the “β” value comes to the “Target_β”. And, in a step S58, the optimum value Peo is determined by multiplying 1/s onto Pwo.
According to the method mentioned above, the possibility is extremely high, that the value Pe′ obtained with the “κ” method is used, as the Pe value when measuring the “β”, therefore it is possible to determine the recording power, correctly. The optimal Pe value differs depending upon a type or a kind of that disk, and also fluctuates upon variation of the drive and/or temperature condition thereof, however, with this method, there can be obtained an effect of enabling stable determination, always, irrespective of those changes.
<Determination Method 2>
In a step S61, the strategy information is read out from the control data of the optical disk or the memory 13 of the apparatus, so as to determine the provisional Pw′ and Pe′ from the values described therein, and the ratio is determined Pw′/Pe′=s. In a step S62, the test signal is recorded with changing the Pw around the provisional Pw′ within the predetermined range n %-m %, while fixing the Pe to the provisional Pe′. In a step S64, the optimum value Pwo is determined from such the Pw that the “β” value comes to the “Target_β”. And, in a step S65, the optimum value Peo is determined by multiplying 1/s onto Pwo.
With this method, the steps for determining the power can be shortened or reduced. Thus, it is possible to omit the steps of the “κ” method (i.e., S51-S54), which are executed in the <Determination Method 1> mentioned above, and thereby enabling to shorten or reduce the time for determining.
<Determination Method 3>
In a step S71, the strategy information is read out from the control data of the optical disk or the memory 13 of the apparatus, so as to determine the provisional Pw′ and Pe′ from the values described therein, and the ratio is determined Pw′/Pe′=s. In a step S72, the test signal is recorded with changing the Pw around the provisional Pw′ within the predetermined range n %-m %, while fixing the Pe to zero (0). However, Pe=0 mentioned herein has no intention to limit to zero, restrictively, but has a meaning to be close to zero (0), approximately, comparing to the other values. In a step 73, the test signal is reproduced, thereby obtaining the “β” value. In a step S74, the optimum value Pwo is determined from such the Pw that the “β” value comes to the “Target_β”. However, in this case, since compensation is made on the shifting of “β” curve due to the presumption, Pe=0, a compensation value is used, as the value of the “Target_,”. In a step S75, the optimum value Peo is determined by multiplying 1/s onto Pwo.
With this method, the “β” curve to be measured is only one (1) piece, and the optimum value obtained from this is independent upon the variation of the apparatus and/or the temperature condition thereof, and therefore a stable result can be expected. Also, the necessary measurement is only a step of one (1) time with the “β” method, and for that reason, it is possible to shorten or reduce the time, greatly.
As was mentioned above, accordance to the optimum recording power determining method mentioned above, for determining the optimum recording power, there is applied the “β” method of obtaining the “β” value with changing the recording power Pw while fixing the erasing power Pe, or is applied the “κ” method of applying the modulation factor “M” as the index. And, according to the present invention, with applying those methods therein, it is possible to determine the optimal recording power with confirming the recording quality during when recording, in particular, also for the optical disk having high density and large capacity, such as, the blu-ray disk, representatively, for example. In more details thereof, it is applied onto the optical disk having high density and large capacity, such as, the blu-ray disk, representatively, for example, and in that instance, in particular, with using the area or region called “APC area” provided in a part of the recoding areas, which is constructed with the areas or regions divided a large number thereof by a unit of the predetermined information recording unit (RUB), being unique to such the disk, it is possible to provide a new method for determining the optimal recording power with confirming the recording quality during when recording.
a) shows the information recording units (RUB), which are formed in a large number thereof, upon the recording surface of the blu-ray disk (BD) mentioned above, and at a head portion thereof is provided the above-mentioned APC area or region, by a unit 5 wbs (wobbles), as is shown in
Firstly,
Thus, with the optimum recording power determining method shown in
Also, with the optimum recording power determining method shown in
Further,
In addition thereto, with the optimum recording power determining method shown in
And, in
Thus, with those various optimum recording power determining methods mentioned above, using the various kinds of methods mentioned above therein, as the method for determining the recording power when measuring “β”, it is possible to determine the optimal recording power with confirming the recording quality during when recording, in particular, when applying in the optical disk having high density and large capacity, such as, the blu-ray disk, representatively, for example. However, herein, detailed explanation was given, in particular, on the method for obtaining “β” while keeping Pe constant, but it should not restricted only thereto, according to the present invention, and it is also possible to achieve with using the “β” method, “γ” method or “κ” method, etc., other than that.
As was mentioned above, according to the present invention, there can be achieved a superior effect of providing the optical disk apparatus and the method for determining a recording power, enabling to determine the optimal recording power while confirming the recording quality during when recording, even for the optical disk having high density and large capacity, such as, the blu-ray disk, representatively, for example.
While we have shown and described several embodiments in accordance with our invention, it should be understood that disclosed embodiments are susceptible of changes and modifications without departing from the scope of the invention. Therefore, we do not intend to be bound by the details shown and described herein but intend to cover all such changes and modifications that fall within the ambit of the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2006-348392 | Dec 2006 | JP | national |
