JP3737948B2 - Optical disk device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical disc apparatus for recording and reproducing information on an optical disc.
[0002]
[Prior art]
In recent years, optical discs have been put to practical use as large-capacity information recording media such as multimedia data, and optical discs capable of high-density recording (hereinafter abbreviated as high-density discs) aiming at further increase in capacity are successively available. Has been announced.
[0003]
As a major approach for increasing the density, recording marks have been shortened and track pitches have been reduced. However, as the density is increased, the influence on the signal quality, such as the S / N ratio, increases when the condensing state of the laser beam changes due to defocusing or disc tilt during recording or reproduction. For this reason, at the time of recording, it is desirable to record with a laser power in which an equivalent laser power decrease due to a change in the condensing state is corrected.
[0004]
For such a problem, the minimum recording power (hereinafter abbreviated as Pmin) for forming a recordable recording mark on the optical disc is detected, and the optimum recording power is calculated by multiplying this Pmin by a constant. A method for setting the optimum recording power as the laser power used for data recording has been proposed (for example, Japanese Patent Laid-Open No. 3-232141).
[0005]
Hereinafter, an example of the above-described conventional optical disc apparatus will be described with reference to the drawings.
[0006]
FIG. 8 is a block diagram of a conventional optical disc apparatus. In FIG. 8, 1 is an optical disk, 2 is a spindle motor that rotates the optical disk, and 3 is an optical head that collects laser light on the optical disk 1 and detects recording information by reflected light from the optical disk 1. Reference numeral 4 denotes laser power control means for setting laser power based on information from the control unit 6 to be described later, and reference numeral 5 denotes a magnetic head for recording signals. A control unit 6 controls the spindle motor 2, the optical head 3, the laser power control means 4, and the magnetic head 5, detects Pmin, and sets an optimum recording power. 7 is a band pass filter, and 8 is a detector for detecting the intensity of the reproduction signal.
[0007]
Next, the operation of the optical disk apparatus configured as described above will be described.
[0008]
First, the laser power control unit 4 sets power based on information from the control unit 6. The control unit 6 controls the optical head 3 and the magnetic head 5 to record a single frequency signal on the optical disc 1. This signal is reproduced by the optical head 3 and band-limited by a band pass filter 7 having the same pass band as the recorded frequency, and then the signal intensity of this output is detected by the detector 8 and the signal intensity is sent to the control unit 6. Enter as. By repeating this operation while changing the set value of the recording power, the recording power dependency as shown in FIG. 9 can be obtained, and Pmin is detected by approximation calculation from this dependency.
[0009]
In the control unit 6, the optimum recording power is calculated by multiplying the Pmin by a constant, and the optimum recording power is set as the laser power used for data recording, whereby the condensing state of the laser beam and the temperature of the optical disk are changed. Even in this case, the recording state can be kept constant.
[0010]
[Problems to be solved by the invention]
However, in the configuration as described above, Pmin detection is performed using the signal intensity of the reproduction signal, and thus Pmin detection has to be performed in an area where data is not recorded. For this reason, the detection of Pmin must be performed in a predetermined area provided on the optical disk such as a power setting area, or when it is performed in the data recording area, the data recorded in the area needs to be erased in advance. . In the former case, the area that cannot be recorded on the optical disk increases and the data recording capacity decreases, and in the latter case, a rotation wait for erasing the data occurs and it takes extra time to detect Pmin. There has been a problem that data on adjacent tracks may be erased (cross erase) at the time of erasing.
[0011]
In view of the above problems, the present invention can detect Pmin with high accuracy and in a short time even when the detection area of the minimum recording power is a data recording area, without having to erase data recorded in the area in advance. An object of the present invention is to provide an optical disc apparatus capable of performing the above.
[0012]
[Means for Solving the Problems]
In order to achieve the above object, a first optical disk apparatus according to the present invention is an optical disk apparatus that records and reproduces data by irradiating an optical disk with a light beam, and a recording unit that records information on the optical disk. Laser power control means for controlling laser power for the recording means, reproducing means for reproducing information recorded on the optical disc, a recording pattern to be recorded on the optical disc by the recording means, and the recording pattern Correlation detecting means for detecting a correlation with a reproduction signal obtained when the reproducing means reproduces the signal, detecting a minimum recording power for forming a record mark of the reproducible limit on the optical disc, and multiplying the minimum recording power by a constant An optimum recording power setting means for setting the recorded power as the optimum recording power,
The optimum recording power setting means compares the output of the correlation detection means obtained when the laser power is changed stepwise by the laser power control means with a predetermined level, and records when the magnitude relationship is changed. The power is detected as the minimum recording power, and the optimum recording power is set.
[0013]
In the first optical disc apparatus, the optimum recording power setting means may detect the minimum recording power in a plurality of areas on the optical disc and set the optimum recording power common to the plurality of areas. preferable.
[0014]
In the first optical disc apparatus, the optimum recording power setting means records the data when it is determined that there is no appropriate optimum recording power based on the detected value of the minimum recording power. It is preferable to stop.
[0015]
In the first optical disc apparatus, it is preferable that the recording unit records a recording pattern in which occurrence probabilities of “0” and “1” are substantially equal when detecting the minimum recording power.
[0016]
In the first optical disc apparatus, it is preferable that the recording unit records a different recording pattern each time the minimum recording power is detected.
[0017]
To achieve the above object, a second optical disk apparatus according to the present invention is an optical disk apparatus that records and reproduces data by irradiating an optical disk with a light beam, and recording means for recording information on the optical disk; Laser power control means for controlling laser power for the recording means, reproducing means for reproducing information recorded on the optical disc, a recording pattern to be recorded on the optical disc by the recording means, and the recording pattern Correlation detecting means for detecting a correlation with a reproduction signal obtained when reproducing by the reproducing means, and a minimum recording power for forming a record mark of a reproducible limit on the optical disc is detected, and the minimum recording power is multiplied by a constant. Optimum recording power setting means for setting the power as the optimum recording power, and the light for detecting the minimum recording power And a position specifying means for specifying a position on the disk,
The optimum recording power setting means compares the output of the correlation detection means obtained when the laser power is changed stepwise by the laser power control means with a predetermined level at the position designated by the position designation means. Then, the recording power when the magnitude relationship is changed is detected as the minimum recording power, and the optimum recording power is set.
[0018]
In the second optical disc apparatus, it is preferable that the position specifying unit specifies a data recording area.
[0019]
In order to achieve the above object, a third optical disk apparatus according to the present invention is an optical disk apparatus for recording and reproducing data by irradiating a light beam onto an optical disk having a power setting area separately from the data recording area. A recording means for recording information on the optical disc, a laser power control means for controlling laser power for the recording means, a reproducing means for reproducing the information recorded on the optical disc, and a recording means for recording on the optical disc. Correlation detecting means for detecting a correlation between a recording pattern to be reproduced and a reproduction signal obtained when the recording pattern is reproduced by the reproducing means, and detecting a minimum recording power for forming a record mark of the reproducible limit on the optical disc The optimum recording power setting method is to set a power obtained by multiplying the minimum recording power by a constant as the optimum recording power. If, comprising a position specifying means for specifying a position on the optical disc for detecting the minimum recording power, and a detection power specifying means for specifying the maximum value of the laser power used for the detection of the minimum recording power,
The position designation means designates the power setting area prior to the data recording area, and the optimum recording power setting means determines the laser power by the laser power control means at the position designated by the position designation means. The output of the correlation detecting means obtained when the change is made is compared with a predetermined level, the recording power when the magnitude relationship is changed is detected as the minimum recording power, and the optimum recording power is set. At the same time, the detected minimum recording power is input to the detected power designating means, and the maximum value of the laser power is determined.
[0020]
In order to achieve the above object, a fourth optical disk apparatus according to the present invention is an optical disk apparatus for recording and reproducing data by irradiating an optical disk with a light beam, and a recording means for recording information on the optical disk. Laser power control means for controlling laser power for the recording means, reproducing means for reproducing information recorded on the optical disc, a recording pattern to be recorded on the optical disc by the recording means, and the recording pattern Correlation detecting means for detecting a correlation with a reproduction signal obtained when the reproducing means reproduces the signal, detecting a minimum recording power for forming a record mark of the reproducible limit on the optical disc, and multiplying the minimum recording power by a constant Optimum recording power setting means for setting the recorded power as the optimum recording power, and a type for detecting the minimum recording power. And a timing designation means for designating a ring,
The optimum recording power setting means compares the output of the correlation detection means obtained when the laser power is changed stepwise by the laser power control means with a predetermined level at the timing designated by the timing designation means. Then, the recording power when the magnitude relationship is changed is detected as the minimum recording power, and the optimum recording power is set.
[0021]
In the fourth optical disc apparatus, the timing designating unit detects a temperature change around the optical disc, and designates a time when the temperature change becomes a predetermined value or more as a timing for detecting the minimum recording power. It is preferable.
[0022]
In the fourth optical disc apparatus, it is preferable that the timing designating unit designates a time when a predetermined time has elapsed since the detection of the minimum recording power as a timing for detecting the minimum recording power. .
[0023]
According to the above configuration, even when the detection area of the minimum recording power is a data recording area, it is not necessary to erase data recorded in the area in advance, and Pmin can be detected with high accuracy and in a short time. It becomes possible.
[0024]
In addition, since Pmin detection can be performed at a position (sector) immediately before recording, an optimum recording power is always set even when there is a change in time such as tilt or warp of the optical disc, defocus, temperature, or the like. It becomes possible.
[0025]
Further, by detecting Pmin in the power setting area and designating the maximum value of the laser power used for Pmin detection based on this value, cross-write can be prevented even in a high-density disk.
[0026]
Furthermore, even when there is a sudden temperature change, Pmin is detected again and the recording power used for data recording is reset, so that the optimum recording power can always be set. .
[0027]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to FIGS.
[0028]
(First embodiment)
FIG. 1 is a block diagram showing the configuration of the optical disc apparatus according to the first embodiment of the present invention.
[0029]
In FIG. 1, 1 is an optical disk, 2 is a spindle motor that rotates the optical disk, and 3 is an optical head (reproducing means) that collects laser light on the optical disk 1 and detects recorded information by reflected light from the optical disk 1. is there. Reference numeral 4 denotes laser power control means for setting laser power based on information from the control unit 21 described later, and reference numeral 5 denotes a magnetic head for recording signals. 21 controls the spindle motor 2, the optical head 3, the laser power control means 4, and the magnetic head 5, and detects the minimum recording power (Pmin) for forming a reproducible limit recording mark on the optical disc 1. It is a control unit (optimum recording power setting means) for setting the optimum recording power. Reference numeral 22 denotes a signal processing unit that performs predetermined processing on the reproduction signal, 23 denotes a clock generation unit that generates a clock used for signal recording and reproduction, and 24 denotes an address demodulator that demodulates the address. Reference numeral 25 denotes a detector (correlation detection means) that detects a correlation between a known recording pattern and a reproduction signal obtained when the recording pattern is reproduced.
[0030]
The optical head 3 and the magnetic head 5 described above constitute recording means. In a phase change type optical disk or the like, a recording means is constituted only by the optical head 3.
[0031]
FIG. 2A shows a configuration diagram of the optical disc 1 according to the first embodiment of the present invention. The optical disc 1 shown in FIG. 2A is also used in the second and fourth embodiments.
[0032]
In FIG. 2A, 11 is a substrate, 12 is a recording film, 13 is a data recording area for recording data, and 14 is a track.
[0033]
Next, the operation of the optical disk apparatus configured as described above will be described.
[0034]
Based on information from the control unit 21, the optical head 3 irradiates the optical disk 1 with a light beam, detects the reflected light, and converts it into an electrical signal. This detection signal is supplied to the signal processing unit 22, the clock generation unit 23, the address demodulator 24, and a focus control unit and tracking control unit (not shown).
[0035]
A reproduction signal corresponding to the recording information recorded on the optical disc 1 is supplied to the signal processing unit 22, and the signal processing unit 22 performs processing such as noise removal.
[0036]
The clock generation unit 23 extracts clock generation information from the signal supplied from the optical head 3 and generates a clock used for signal recording and reproduction. This clock is supplied to the control unit 21 and the detector 25.
[0037]
For example, in a sample servo type optical disc, clock pits, which are clock generation information, are recorded (preformatted) in advance over the entire circumference, and this information is detected from a signal supplied from the optical head 3, and a PLL, for example, is detected. By using and dividing, a clock used for recording and reproduction can be generated. Of course, the clock generation information does not have to be recorded in pits, and may or may not have grooves (grooves), or may be grooves (grooves) meandering at a predetermined frequency. . The optical system is not limited to the sample servo type optical disk, and may be an external clock type optical disk apparatus that always uses the same clock for recording and reproduction.
[0038]
The address demodulator 24 extracts address information from the signal supplied from the optical head 3, demodulates the address based on this information, and knows which position on the optical disc 1 is irradiated with the light beam. Is detected. The detected address is supplied to the control unit 21 and the detector 25.
[0039]
Next, operations of the control unit 21 and the detector 25 will be described using the timing chart of FIG.
[0040]
FIG. 3A shows a clock generated by the clock generator 23.
[0041]
First, the laser power control unit 4 sets a sufficiently low power (for example, P0) as compared with the power for actually recording data, based on information from the control unit 21. Based on the information from the control unit 21, the optical head 3 and the magnetic head 5 generate a recording pattern synchronized with the clock (FIG. 3A) by the laser power control means 4 as shown in FIG. Recording is performed on the optical disc 1 with the set power.
[0042]
At this time, the laser power control means 4 changes the recording power step by step over a predetermined number of stages with P0 as an initial value, as shown in FIG. 3C, based on information from the control unit 21. Power setting is performed (the recording power at each stage is P0, P1, P2,...).
[0043]
Further, the recording pattern (FIG. 3B) is also supplied to the detector 25.
[0044]
In FIG. 3C, the recording power is shown to monotonously increase. However, the present invention is not limited to this, and the recording power may be monotonously decreased or may be set so that the increase and decrease are repeated. Good.
[0045]
When this recording pattern is reproduced by the optical head 3 and input to the signal processing unit 22, low-frequency noise is removed by the signal processing unit 22, and then a reproduction signal as shown in FIG. Is done. In addition to the noise component, if the area where Pmin is detected is not an unrecorded area, the reproduced signal includes a signal component of data previously recorded in the area.
[0046]
The detector 25 detects the correlation between the recording pattern (FIG. 3 (b)) and the reproduction signal (FIG. 3 (d)). This is nothing but the detection of autocorrelation, and by this, it can be known how accurately the recording pattern recorded with each recording power is recorded. The detected result is input to the control unit 21 as a correlation value.
[0047]
Here, since the same clock (FIG. 3A) is used for signal recording and reproduction, for example, in FIG. 3, a period in which the recording pattern (FIG. 3B) is logic “H” is expressed as “ 1 ", a period of logic" L "is set to" -1 ", the product of the recording pattern and the reproduction signal (Fig. 3 (d)) is taken and integrated for a predetermined period, so that noise components and previously recorded Signal components that have no correlation with the recording pattern, such as data, are canceled out. For this reason, even if the signal is very small, the signal component of the recording pattern recorded on the optical disc 1 can be detected, and the detector 25 detects this as a correlation value.
[0048]
For example, as shown in FIG. 3E, the correlation value is obtained by dividing the integration result for each stage recorded with the same power according to the integration period (t0, t1, t2,...). Here, the correlation values detected at each stage are C0, C1, C2,. In an area where the power is low and recording is not performed, the correlation value is almost 0 (zero).
[0049]
If it is known that the integration periods (t0, t1, t2,...) Are the same for each recording power, the integration result may be used as a direct correlation value without being divided according to the integration period.
[0050]
Further, the detector 25 may detect the correlation by setting the period in which the recording pattern (FIG. 3B) is logic “H” to “−1” and the period in which logic “L” is “1”. .
[0051]
The control unit 21 compares the correlation value with a predetermined level and detects that the magnitude relationship has changed. Then, the recording power (for example, P2 in FIG. 2) for recording this recording pattern is detected from the address at this time, and this is set as Pmin. Further, the control unit 21 multiplies Pmin by a constant to calculate the optimum recording power, and sets this as the laser power used for data recording.
[0052]
Thus, even when the detection area of the minimum recording power for the optical disc 1 is the data recording area 13, it is not necessary to erase data recorded in the area in advance, and Pmin can be detected with high accuracy and in a short time. It becomes possible. In addition, since it is possible to detect a minute signal component, it is possible to detect Pmin using a power sufficiently lower than the power for recording data in the vicinity of Pmin. There is no risk of cross-lighting that writes data to adjacent tracks.
[0053]
The reproduction signal (FIG. 3D) may be input to the detector 25 after being digitized by an A / D converter (not shown). Similarly, in this case, in the detector 25, the period when the recording pattern (FIG. 3B) is logic “H” is “1”, the period when the recording pattern is “L” is “−1”, or the logic “ The period of “H” is “−1”, the period of logic “L” is “1”, and the recorded pattern is multiplied by the digitized reproduction signal, and the multiplied value is multiplied by a predetermined period (for example, t0, t1,. The correlation can be detected by adding t2,.
[0054]
Further, when Pmin is detected in the control unit 21, erroneous detection of Pmin can be prevented by detecting the continuity of the correlation values (C0, C1, C2,...) Together. For example, when the recording power is changed to Pn-1, Pn, Pn + 1 (where Pn-1 <Pn <Pn + 1), the recording pattern is recorded, and the correlation values detected at this time are Cn-1, Cn, Cn + 1 Even if Cn−1 <predetermined level <Cn is satisfied and the magnitude relationship with the predetermined level is changed, if Cn> Cn + 1, Cn is considered to include a detection error, and Pn is not Pmin.
[0055]
In addition, by detecting Pmin in a plurality of areas on the optical disc 1 and setting the optimum recording power, it is possible to set the optimum recording power for disc sensitivity variations and the like.
[0056]
The optical disk 1 may have uneven sensitivity. For example, in the track 14, as shown by the solid line in FIG. At this time, the optimum recording power also varies depending on Pmin. In FIG. 2B, the horizontal axis represents the position and area on the circumference of the track 14, and the vertical axis represents Pmin at each position. This is caused by, for example, a variation in the film thickness of the recording film 12, and heat is not easily transmitted in a thick film region, and extra heat is required, so Pmin is high, and conversely, Pmin is low in a thin film region. Become.
[0057]
At this time, when Pmin is detected in the vicinity of the area A, P3 is detected as Pmin, so that a high recording power is set for the area around the area C, and there is a risk of cross writing. . In addition, when Pmin is detected around the area C, P1 is detected as Pmin. Therefore, a low recording power is set for the area around the area A, and sufficient signal quality can be obtained. There is no fear.
[0058]
For this reason, Pmin is detected in areas A, B, and C, which can be obtained by dividing a plurality of areas on the optical disc 1, for example, one track, and the detected values in each area are Pmin-A, Pmin-B, and Pmin. -C.
[0059]
Here, considering that the data is recorded by switching the laser power within one track, control such as power control in the laser power control means 4 and gain control in the focus control unit and tracking control unit (not shown) is very important. Since it becomes complicated, it is desirable to set one laser power that can be commonly used in a plurality of regions.
[0060]
Therefore, by setting the average value of the detected values of Pmin (for example, Pmin-A, Pmin-B, Pmin-C) in a plurality of regions as Pmin in the track 14, Pmin is detected as the power near P2, and the optimum value is detected. Recording power can be set.
[0061]
Note that not all of Pmin (Pmin-A, Pmin-B,..., Pmin-N) detected in a plurality of areas on the optical disc 1, but the remaining detection values excluding the maximum value and / or the minimum value. The Pmin of the region, for example, the track 14 may be obtained by taking the average of the above, or the Pmin may be obtained by other methods without being limited to the average.
[0062]
Further, the area within one track for detecting Pmin is not limited to three, and may be two or four or more. In FIG. 2A, the track 14 is concentric, but the present invention is not limited to this, and the track 14 may be formed in a spiral shape.
[0063]
Further, the plurality of areas for detecting Pmin are not limited to areas obtained by dividing one track, and may be areas on the same radial direction of the optical disk 1 or arbitrary areas on the optical disk 1. Good.
[0064]
This makes it possible to set an optimum recording power even when the sensitivity of the optical disk is uneven. In addition, when Pmin is detected by removing the maximum value from Pmin detected in a plurality of areas and Pmin becomes extremely high due to dust and fingerprints attached on the disk, this is followed. It is possible to prevent the recording power from being set high. Further, by detecting Pmin by removing the maximum value and / or the minimum value from Pmin detected in a plurality of areas, it is possible to prevent an erroneous recording power from being set due to a Pmin detection error or the like.
[0065]
The non-uniformity of sensitivity of the optical disc 1 is not limited to the variation in the film thickness of the recording film 12, but may be due to the variation in the film thickness of other films (not shown) or may be due to other factors. Good.
[0066]
Further, when it is determined that there is no appropriate optimum recording power based on the detected value of Pmin, it is possible to prevent the optical head 3 from being destroyed or cross-written by stopping the data recording.
[0067]
When the condensing state of the laser beam is deteriorated or at a low temperature, the detected Pmin is high, and accordingly, the recording power set as the optimum recording power in the control unit 21 is also high. However, if the power of a predetermined level or higher is output, the optical head 3 may be destroyed. Therefore, if the detected Pmin is higher than the predetermined level, the control unit 21 determines that there is no appropriate recording power. And stop data recording.
[0068]
Further, when Pmin is detected in a plurality of areas on the optical disc 1, if the detected values of Pmin have a predetermined variation or more, the control unit 21 does not have an appropriate value as the recording power. Judgment is made and data recording is stopped. That is, when the sensitivity unevenness of the optical disc 1 is as indicated by the dotted lines in FIG. 2B, cross-writing occurs in the area C when recording is performed at the optimum recording power in the area A, and area is recorded when recording is performed at the optimum recording power in the area C. A may not provide sufficient signal quality.
[0069]
As a result, it is possible to prevent the optical head 3 from being destroyed due to an excessive output of the laser and recording at a laser power that may cause a cross light.
[0070]
Further, when detecting Pmin, the DC component in the noise included in the reproduction signal (FIG. 3C) is canceled by using a recording pattern in which the occurrence probability of “0” and “1” is substantially equal. Is possible.
[0071]
Due to variations in photoelectric conversion elements (not shown) in the optical head 3 and offsets generated in an electric circuit (not shown) in the signal processing unit 22, the reproduced signal (FIG. 3C) may include DC noise. .
[0072]
Here, when the occurrence probabilities of “0” and “1” of the recording pattern are different, the correlation value is offset by the difference, which becomes a detection error. For this reason, by detecting a correlation value using a recording pattern having the same occurrence probability of “0” and “1” within an integration period (for example, t0, t1, t2,...) At each recording power, The DC components are canceled out, and a correlation value can be obtained with little detection error. Further, since Pmin is detected using this correlation value, it goes without saying that this improves the accuracy of Pmin.
[0073]
Further, when the occurrence probability of “0” and “1” cannot be made equal, such as when the number of data bits in the integration period (for example, t0, t1, t2,. A simple recording pattern may be used.
[0074]
Note that DC noise included in the reproduction signal (FIG. 3C) is limited to that due to variations in photoelectric conversion elements in the optical head 3 and offsets generated in an electric circuit (not shown) in the signal processing unit 22. It may be due to other factors.
[0075]
This makes it possible to detect Pmin with high accuracy.
[0076]
Further, by using a different recording pattern for each detection of Pmin, it is not necessary to previously erase the recording pattern recorded by the previous detection of Pmin at the same position (sector), and Pmin detection can be performed a plurality of times. It becomes possible.
[0077]
This is the same as the fact that previously recorded data need not be erased in advance in the data recording area 13. That is, even when the reproduction signal (FIG. 3C) includes a recording pattern (for example, b0) recorded at the time of detecting the previous Pmin, the recording pattern (FIG. 3B) and b0 are recorded. If there is no correlation, the signal component b0 is canceled by the detector 25, so that the recording pattern (FIG. 3B) can be detected.
[0078]
For example, when detecting Pmin, an M-sequence generating circuit (not shown) generates an M-sequence random pattern, which is input to the control unit 21 and used as a recording pattern, thereby recording a different recording pattern for each detection of Pmin. It becomes possible to do.
[0079]
Thereby, a different recording pattern is recorded every time Pmin is detected, and even when the recording pattern recorded at the time of detecting Pmin is not erased, this recording is performed when Pmin is detected at the same position (sector) next time. It is not necessary to erase the pattern in advance, and Pmin can be detected in any recordable area on the optical disk. In addition, since it is not necessary to erase previously recorded data and recording patterns, it is possible to detect Pmin in a short time.
[0080]
(Second Embodiment)
FIG. 4 is a block diagram showing the configuration of the optical disc apparatus according to the second embodiment of the present invention. In FIG. 4, the same reference numerals as those in FIG. 1 denote the same components, and description thereof will be omitted.
[0081]
In FIG. 4, reference numeral 31 denotes a control unit (optimal recording power setting unit) that controls the spindle motor 2, the optical head 3, the laser power control unit 4, and the magnetic head 5, detects Pmin, and sets the optimum recording power. ). Reference numeral 32 denotes position specifying means for specifying a position on the optical disc 1 for detecting Pmin.
[0082]
Next, the operation of the optical disc apparatus configured as described above will be described below.
[0083]
The position designation unit 32 designates the position on the optical disc 1 where Pmin is detected with respect to the control unit 31. The control unit 31 detects Pmin at the designated position, multiplies this Pmin by a constant, calculates the optimum recording power, and sets this optimum recording power as the laser power used for data recording. The method for detecting Pmin is the same as in the first embodiment.
[0084]
The tilt and warp of the optical disk 1 may vary depending on the position of the optical disk, and the temperature on the optical disk surface may change with time. When the condensing state of the laser beam changes due to the tilt or defocus of the optical disc 1, the equivalent laser power used for recording and reproduction changes, so Pmin and the optimum recording power change accordingly. Further, Pmin and the optimum recording power greatly depend on the temperature on the disk surface.
[0085]
For this reason, immediately before data is recorded, the position designation means 32 designates a position (sector) in the data recording area 13 where recording will be performed. The control unit 31 detects Pmin at this position (sector), calculates the optimum recording power by multiplying this by a constant, and resets this optimum recording power as the laser power used for data recording.
[0086]
This makes it possible to always set the optimum recording power even when the light condensing state changes due to the position on the optical disc 1 and the change with time, or when the temperature on the disc surface changes.
[0087]
Note that the detection of Pmin is not limited to being performed immediately before recording data, but a plurality of positions (for example, the innermost and outermost circumferences) on the optical disc 1 are designated in advance by the position designation unit 32, and the respective positions are designated. When Pmin is detected and data is recorded, Pmin at each position to be recorded may be calculated by interpolation or the like using Pmin at each position detected previously.
[0088]
Also in this case, since Pmin can be detected using the data recording area, it is not necessary to provide a predetermined area such as a power setting area on the optical disc 1 in advance.
[0089]
As a result, even when the light condensing state changes depending on the position on the optical disc 1, it is possible to set the optimum recording power for each position (sector).
[0090]
(Third embodiment)
FIG. 5 is a block diagram showing a configuration of an optical disc apparatus according to the third embodiment of the present invention. In FIG. 5, the same reference numerals as those in FIG. 1 or FIG. 4 denote the same components, and a description thereof will be omitted.
[0091]
In FIG. 5, reference numeral 40 denotes an optical disk having a power setting area separately from the data recording area, 41 denotes control of the spindle motor 2, optical head 3, laser power control means 4, and magnetic head 5, and detection of Pmin. A control unit (optimal recording power setting means) for setting the optimum recording power. Reference numeral 42 denotes detection power designating means for designating the maximum value of the laser power used for detecting Pmin.
[0092]
FIG. 6 shows a configuration diagram of an optical disc 40 according to the third embodiment of the present invention.
[0093]
In FIG. 6, the same reference numerals as those in FIG. 3 denote the same components, and a description thereof will be omitted.
[0094]
In FIG. 6, reference numeral 15 denotes a power setting area provided on the optical disc 40 in advance for detecting the optimum power during recording and / or reproduction.
[0095]
Next, the operation of the optical disk apparatus configured as described above will be described.
[0096]
Immediately after the optical disc 40 is inserted and when the system controller (not shown) resets to the same state as immediately after the disc insertion, the position designation means 32 designates the power setting area 15 and the control unit 41 detects Pmin in this area. . The method for detecting Pmin is the same as in the first embodiment. Let Pmin detected here be Ptest.
[0097]
The detected Pmin value (Ptest) is also input to the detection power designation means 42, and the detection power designation means 42 multiplies the inputted Pmin value (Ptest) by a predetermined value (this is referred to as Pa).
[0098]
Next, immediately before the data is recorded, the position specifying means 32 specifies the position (sector) in the data recording area 13 where recording will be performed.
[0099]
The detection power designation means 42 designates Pa as the maximum value of the laser power used for detecting Pmin to the control unit 41.
[0100]
Based on the information from the control unit 41, the laser power control means 4 sets a power (for example, P0) that is sufficiently lower than the power for recording actual data. Based on the information from the control unit 41, the optical head 3 and the magnetic head 5 make a recording pattern synchronized with the clock generated by the clock generation unit 23 with the power set by the laser power control unit 4 and the position specifying unit 32. Is recorded at the position (sector) designated by.
[0101]
At this time, the laser power control means 4 is designated by the detection power designation means 42 so as to change the recording power step by step over a predetermined number of stages with P0 as an initial value based on information from the control unit 41. The power is set so as not to exceed the power (Pa).
[0102]
Here, in the case of this embodiment, it is different from the first and second embodiments that the maximum value of the laser power used for the detection of Pmin is determined.
[0103]
This recording pattern is also supplied to the detector 25.
[0104]
When this recording pattern is reproduced by the optical head 3 and input to the signal processing unit 22, the low frequency noise is removed by the signal processing unit 22, and then the reproduction signal is input to the detector 25. In addition to the noise component, this reproduced signal includes a signal component of data previously recorded in this area if the area where Pmin is detected is not an unrecorded area.
[0105]
The detector 25 detects the correlation between the recording pattern and the reproduction signal. This is nothing but the detection of autocorrelation, and this makes it possible to know how accurately the recording pattern recorded at each recording power is recorded. The detected result is input to the control unit 41 as a correlation value. The control unit 41 compares the correlation value with a predetermined level, detects that the magnitude relationship has changed, detects the recording power for recording this recording pattern from the address at that time, and designates this as Pmin. The control unit 41 calculates the optimum recording power by multiplying Pmin by a constant, and sets the optimum recording power as the laser power used for data recording.
[0106]
If the correlation value does not exceed a predetermined level even at the maximum laser power (Pa), the detection power specifying means 42 further multiplies Pa by a predetermined value (this is set as Pb). Next, the detection power designation means 42 designates Pb as the maximum value of the laser power used for detecting Pmin to the control unit 41. Thereafter, this is repeated, and until the control unit 41 detects Pmin, the detection power designation means 42 sequentially increases the maximum value of the laser power used for detection of Pmin. Note that the control unit 41 stops data recording when the maximum value of the laser power specified by the detection power specifying means 42 exceeds a predetermined level.
[0107]
In a high-density disk with a narrow track pitch, cross-writing during recording becomes a problem. For this reason, when detecting Pmin in the data recording area 13, it is desirable to record a recording pattern with a power as low as possible near Pmin. Here, Pmin is detected using the power setting area 15, and a predetermined multiple thereof is set to the maximum value of the laser power used for detecting Pmin in the data recording area 13. Recording and cross-writing can be prevented.
[0108]
This is because Pmin detected in the data recording area 13 is detected in advance in the power setting area 15 when the temperature change of the disk is assumed to be gradual after a predetermined time has elapsed after the optical disk 40 is inserted. This is because it is assumed that there will be no significant change. Therefore, by setting a value (Pa) slightly larger than Ptest as the maximum value of Pmin, it becomes possible to detect Pmin most efficiently while preventing cross light.
[0109]
Note that once Pmin is detected in the data recording area 13, this may be set as Ptest, Pa may be set again, and then used as the maximum value when detecting Pmin in the data recording area 13.
[0110]
If the correlation value does not exceed a predetermined level even at the maximum laser power (Pa), the power setting area 15 is designated again by the position designation means 32 before detecting Pmin in the data recording area 13 next time. It is desirable to detect Ptest and reset the Pa by the detection power designation means 42.
[0111]
As a result, even in the data recording area, it is possible to prevent cross writing and detect Pmin in a short time.
[0112]
(Fourth embodiment)
FIG. 7 is a block diagram showing a configuration of an optical disc apparatus according to the fourth embodiment of the present invention. In FIG. 7, the same reference numerals as those in FIG. 1 denote the same components, and a description thereof will be omitted.
[0113]
In FIG. 7, reference numeral 51 denotes a control unit (optimal recording power setting unit) that controls the spindle motor 2, the optical head 3, the laser power control unit 4, and the magnetic head 5, detects Pmin, and sets the optimum recording power. ). Reference numeral 52 denotes timing designation means for designating timing for detecting Pmin.
[0114]
Next, the operation of the optical disk apparatus configured as described above will be described.
[0115]
The timing designating unit 52 detects a temperature change around the optical disc 1 and / or an elapsed time after detecting Pmin, and outputs a timing signal to the control unit 51 as necessary. The control unit 51 detects Pmin according to the timing signal, calculates the optimum recording power by multiplying the Pmin by a constant, and sets the optimum recording power as the laser power used for data recording. The method for detecting Pmin is the same as in the first embodiment.
[0116]
For example, a thermistor (not shown) can be used as temperature detection means for detecting the temperature around the optical disk. For example, a timer (not shown) can be used as the elapsed time detecting means for detecting the elapsed time after detecting Pmin.
[0117]
The temperature on the optical disk surface may change with time. Since Pmin and optimum recording power greatly depend on the temperature on the optical disk surface, if the temperature around the optical disk changes rapidly, Pmin is detected again and the laser power used for data recording can be reset. desirable.
[0118]
The timing designating unit 52 detects a temperature change around the optical disk from the output of a temperature detection unit (not shown), and outputs a timing signal when the temperature change exceeds a predetermined amount. This makes it possible to always set an optimum recording power even when there is a sudden temperature change.
[0119]
Further, the tilt and warpage of the optical disc 1 may vary depending on the position of the optical disc. When the condensing state of the laser beam changes due to the tilt or defocus of the optical disc 1, the equivalent laser power used for recording and reproduction changes, so Pmin and the optimum recording power change accordingly. For this reason, it is desirable to periodically detect Pmin and reset the laser power used for data recording.
[0120]
The timing designating unit 52 detects an elapsed time after detecting Pmin from an output of an elapsed time detecting unit (not shown), and outputs a timing signal when a predetermined amount of time has elapsed. This makes it possible to set an optimum recording power constantly.
[0121]
Here, as described above, the detection of Pmin according to the present invention can be performed in the data recording area 13 without having to erase the data recorded in the area in advance. It can be done in a short time. That is, there is no need to wait for rotation for erasing data, and there is no need to move the optical head 3 and the magnetic head 5 to a predetermined area provided in advance on the optical disk such as a power setting area. Even when Pmin is frequently detected at the timing specified by, the optimum recording power can be set very effectively without greatly affecting the operation of the system.
[0122]
In the first to fourth embodiments, the detection of the recordable minimum recording power has been described. Similarly, by changing the magnetic field and the linear velocity, the recording mark of the reproducible limit on the optical disc is recorded. It is also possible to detect the minimum magnetic field forming the minimum or the minimum linear velocity.
[0123]
【The invention's effect】
As described above, according to the present invention, even when the detection area of the minimum recording power is set as the data recording area, it is not necessary to erase the data recorded there in advance, and Pmin can be detected with high accuracy and in a short time. It becomes possible to do.
[0124]
In addition, since Pmin detection can be performed at the track immediately before recording, it is possible to always set the optimum recording power even when there is a change in time such as tilt or warp of the optical disc, defocus, temperature, etc. become.
[0125]
Further, by detecting Pmin in the power setting area and designating the maximum value of the laser power used for detecting Pmin as the reference of this value, cross-write can be prevented even in a high-density disk.
[0126]
Furthermore, even if there is a sudden temperature change, Pmin is detected again and the recording power used for data recording is reset, so it is possible to always set the optimum recording power. It is very effective in practical use.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of an optical disc apparatus according to a first embodiment of the present invention.
FIG. 2 is a configuration diagram of an optical disc according to the first embodiment, the second embodiment, and the fourth embodiment of the present invention.
3 is a signal waveform diagram of each part of the optical disc apparatus shown in FIG.
FIG. 4 is a block diagram showing a configuration of an optical disc apparatus according to a second embodiment of the present invention.
FIG. 5 is a block diagram showing a configuration of an optical disc device according to a third embodiment of the present invention.
FIG. 6 is a configuration diagram of an optical disc according to a third embodiment of the present invention.
FIG. 7 is a block diagram showing a configuration of an optical disc apparatus according to a fourth embodiment of the present invention.
FIG. 8 is a block diagram showing the configuration of a conventional optical disc apparatus
FIG. 9 is a diagram showing the recording power dependence of the reproduction signal intensity.
[Explanation of symbols]
1, 40 Optical disc
2 Spindle motor
3 Optical head (reproducing and recording means)
4 Laser power control means
5 Magnetic head (recording means)
6, 21, 31, 41, 51 Control unit (optimum recording power setting means)
7 Bandpass filter
8 Detector
11 Substrate
12 Recording film
13 Data recording area
14 tracks
15 Power setting area
22 Signal processor
23 Clock generator
24 Address demodulator
25 Detector (Correlation detection means)
32 Position designation means
42 Detection power designation means
52 Timing designation means

Claims (11)

An optical disk device for recording and reproducing data by irradiating an optical disk with a light beam,
Recording means for recording information on the optical disc;
Laser power control means for controlling laser power for the recording means;
Reproducing means for reproducing information recorded on the optical disc;
Correlation detecting means for detecting a correlation between a recording pattern to be recorded on the optical disc by the recording means and a reproduction signal obtained when the recording pattern is reproduced by the reproducing means;
An optimum recording power setting means for detecting a minimum recording power for forming a reproducible limit recording mark on the optical disc and setting a power obtained by multiplying the minimum recording power by a constant as an optimum recording power;
The optimum recording power setting means compares the output of the correlation detection means obtained when the laser power is changed stepwise by the laser power control means with a predetermined level, and records when the magnitude relationship is changed. An optical disc apparatus, wherein power is detected as the minimum recording power and the optimum recording power is set. 2. The optimum recording power setting means detects the minimum recording power in a plurality of areas on the optical disc, and sets the optimum recording power common to the plurality of areas. Optical disk device. 2. The data recording apparatus according to claim 1, wherein the optimum recording power setting means stops the recording of the data when it is determined that there is no appropriate optimum recording power based on the detected value of the minimum recording power. Alternatively, the optical disk apparatus according to claim 2. 2. The optical disc apparatus according to claim 1, wherein the recording means records a recording pattern in which occurrence probabilities of “0” and “1” are substantially equal when detecting the minimum recording power. 2. The optical disc apparatus according to claim 1, wherein the recording unit records a different recording pattern each time the minimum recording power is detected. An optical disk device for recording and reproducing data by irradiating an optical disk with a light beam,
Recording means for recording information on an optical disc;
Laser power control means for controlling laser power for the recording means;
Reproducing means for reproducing information recorded on the optical disc;
Correlation detecting means for detecting a correlation between a recording pattern to be recorded on the optical disc by the recording means and a reproduction signal obtained when the recording pattern is reproduced by the reproducing means;
An optimum recording power setting means for detecting a minimum recording power for forming a record mark of a reproducible limit on the optical disc, and setting a power obtained by multiplying the minimum recording power by a constant as an optimum recording power;
Position specifying means for specifying a position on the optical disc for detecting the minimum recording power,
The optimum recording power setting means compares the output of the correlation detection means obtained when the laser power is changed stepwise by the laser power control means with a predetermined level at the position designated by the position designation means. An optical disc apparatus characterized by detecting the recording power when the magnitude relationship is changed as the minimum recording power and setting the optimum recording power. 7. The optical disc apparatus according to claim 6, wherein the position specifying unit specifies a data recording area. An optical disc apparatus that records and reproduces data by irradiating an optical disc with a power setting area separately from a data recording area,
Recording means for recording information on an optical disc;
Laser power control means for controlling laser power for the recording means;
Reproducing means for reproducing information recorded on the optical disc;
Correlation detecting means for detecting a correlation between a recording pattern to be recorded on the optical disc by the recording means and a reproduction signal obtained when the recording pattern is reproduced by the reproducing means;
An optimum recording power setting means for detecting a minimum recording power for forming a record mark of a reproducible limit on the optical disc, and setting a power obtained by multiplying the minimum recording power by a constant as an optimum recording power;
Position designation means for designating a position on the optical disc for detecting the minimum recording power;
Detection power designation means for designating a maximum value of laser power used for detection of the minimum recording power,
The position designation means designates the power setting area prior to the data recording area, and the optimum recording power setting means determines the laser power by the laser power control means at the position designated by the position designation means. The output of the correlation detecting means obtained when the change is made is compared with a predetermined level, the recording power when the magnitude relationship is changed is detected as the minimum recording power, and the optimum recording power is set. In addition, an optical disc apparatus characterized in that the detected minimum recording power is input to the detected power specifying means to determine the maximum value of the laser power. An optical disk device for recording and reproducing data by irradiating an optical disk with a light beam,
Recording means for recording information on the optical disc;
Laser power control means for controlling laser power for the recording means;
Reproducing means for reproducing information recorded on the optical disc;
Correlation detecting means for detecting a correlation between a recording pattern to be recorded on the optical disc by the recording means and a reproduction signal obtained when the recording pattern is reproduced by the reproducing means;
An optimum recording power setting means for detecting a minimum recording power for forming a record mark of a reproducible limit on the optical disc, and setting a power obtained by multiplying the minimum recording power by a constant as an optimum recording power;
Timing designation means for designating timing for detecting the minimum recording power,
The optimum recording power setting means compares the output of the correlation detection means obtained when the laser power is changed stepwise by the laser power control means with a predetermined level at the timing designated by the timing designation means. An optical disc apparatus characterized by detecting the recording power when the magnitude relationship is changed as the minimum recording power and setting the optimum recording power. 10. The timing designating unit detects a temperature change around the optical disc, and designates a time when the temperature change becomes a predetermined value or more as a timing for detecting the minimum recording power. The optical disk device described. 10. The optical disc apparatus according to claim 9, wherein the timing designating unit designates a time when a predetermined time has elapsed since the minimum recording power was detected as a timing for detecting the minimum recording power.

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