JP2004086955A - Optical disk drive - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To record data on a groove while surely reproducing a land prepit, in a data recordable optical disk drive. <P>SOLUTION: The data are recorded on the optical disk 10 such as a DVD-R. In data recording operation, the land prepit LPP formed on the land is reproduced and the data are recorded on the groove while ascertaining an address. By a controller 20, the focus offset is set between the optimum recording focus offset for the data recording and the optimum focus offset for the address reproduction, and the data are recorded . Also, by the controller 20, the power of laser beams is controlled to be increased by considering the deviation of the set focus offset from the optimum recording focus offset. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an optical disk device, and more particularly, to a focus position adjustment during data recording.
[0002]
[Prior art]
2. Description of the Related Art In an optical disk device such as a DVD-R drive capable of recording data, data is recorded while demodulating address information formed in advance on the optical disk to determine the address of the optical disk. As a method of forming address information, there is a method of embedding a track in a meandering (wobble) manner and a method of forming a prepit in a land area adjacent to a groove which is an information recording track. In the DVD-RAM, information recording tracks are lands and grooves, and address information is embedded in an embossed portion of a rewritable area including an embossed portion and a data portion. In the present application, address information (land pre-pits: LPP) in which pre-pits are formed on lands is targeted.
[0003]
FIG. 7 shows the formation positions of the land pre-pits (LPP). The LPPs 100 are formed on the lands at predetermined intervals. Data recorded in the groove is divided into frames (SYNC frames), which are information units. One sector is composed of 26 SYNC frames, and one ECC block is composed of 16 sectors. Synchronization information (SYNC) 200 for establishing synchronization for each SYNC frame is inserted at the beginning of each SYNC frame. As the synchronization information SYNC, 14T sufficiently longer than the longest 11T appearing in the data modulation portion is used so that SYNC frame synchronization can be reliably established. That is, data to be recorded is modulated and recorded at 3T to 11T, and 14T is used as synchronous data. According to the DVD-R standard, either a mark or a space can be selected as a 14T SYNC pulse. Here, a mark is a section where pits are formed, and a space is a section between marks. Explaining from the laser light power, recording power is applied in the mark section, and bias power (reproduction power) is applied in the space section. In FIG. 7, the groove wobbles at a predetermined frequency to detect the rotation speed of the optical disk. The wobble frequency is proportional to the rotation speed of the optical disk.
[0004]
FIG. 8 schematically shows the relationship between a SYNC frame, synchronization information (in the figure, simply referred to as SY), and LPP 100. The SYNC frame is roughly classified into an even frame (EVEN frame) and an odd frame (ODD frame), and the LPP 100 is formed corresponding to the even frame. However, if the LPPs 100 are arranged at substantially the same positions on both lands on both sides of the groove to be recorded, two LPP components will be mixed into the return light. It is arranged shifted. The wobble frequency is eight times the SYNC frame frequency, and the LPP 100 is arranged with 3 bits so as to be located at the top of the first three wobbles in one SYNC frame, of which the first pre-pit indicates the synchronization position. It becomes SYNC pre-pits. The relative address is defined by the LPP located at the top of five even-numbered frames from the top of one sector. For example, the address of the first sector is defined by “111, 100, 100, 100, 100”. The addresses of two sectors are defined by “111, 100, 100, 100, 101”.
[0005]
[Problems to be solved by the invention]
As described above, at the time of data recording, the desired data is recorded while demodulating the component of the LPP 100 included in the return light from the optical disc and determining the address. The land on which the LPP is formed and the groove on which the data is to be recorded are recorded. Since the optical characteristics, that is, the distance from the optical pickup are different, the optimum focus position for reproducing LPP and the optimum focus position for recording / reproducing data are different. Therefore, if the focus position (or the focus offset for setting the focus position to a desired position) is set to the optimum value for the LPP reproduction by giving importance to the LPP reproduction, the recording quality when recording data in the groove deteriorates, Conversely, if the focus position or focus offset at the time of data recording is set to an optimum value for data recording, there is a problem that the reproduction rate of LPP deteriorates.
[0006]
On the other hand, Japanese Patent Application Laid-Open No. H11-316959 discloses that a center value of a range where a laser beam can be defocused in reproducing an address and a range in which a laser beam can be defocused in reproducing data overlap. Describes that a focus position is set. This technique is a technical idea of setting a focus position in the middle between the two, and it is conceivable to solve the above problem by using this idea. However, as a result, the focus position is shifted from an optimum position for data recording. Therefore, the recording quality is degraded.
[0007]
FIG. 9 shows the relationship between the focus (FS) offset, the recording jitter, and the LPP address error. The recording jitter is minimum when the FS offset is FSW, and the LPP address error is minimum when the FS offset is FSLPP. The FS offset should be set near the FSW from the viewpoint of improving the recording quality when recording data in the groove, and the FS offset should be set near the FSLPP from the viewpoint of placing importance on the address reproduction rate of the LPP. In the above prior art, the FS offset is set between the FSW and the FSLPP. However, the recording jitter is minimized when the FS offset is the FSW, and when the SF offset is shifted from this position, the recording jitter is reduced accordingly. Recording jitter increases.
[0008]
SUMMARY OF THE INVENTION The present invention has been made in consideration of the above-described problems of the related art, and an object of the present invention is to provide an optical disk device that can reliably reproduce address information and maintain data recording quality.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides an optical disc apparatus for recording data on an optical disc in which address information is formed in advance, wherein the focus position is determined by an optimum recording focus position for recording data and the address information. It is characterized in that it has a focus adjusting means for adjusting between the optimum address reproduction focus positions for reproduction and a power adjusting means for adjusting the recording laser beam power in conjunction with the adjustment of the focus position.
[0010]
It is preferable that the focus adjustment unit adjusts the focus position so that an error rate of the address information is equal to or less than a predetermined value.
[0011]
Further, it is preferable that the power adjustment unit increases the recording laser beam power in accordance with a difference between the focus position adjusted by the focus adjustment unit and the optimum recording focus position.
[0012]
Further, it is preferable that the power adjustment unit records test data at a focus position obtained by the adjustment by the focus adjustment unit, and adjusts the recording laser beam power based on a reproduction signal quality of the test data. .
[0013]
Further, the focus adjustment means adjusts the focus position prior to actual data recording, and further includes means for detecting an error rate of the address information during actual data recording at the adjusted focus position. The focus adjustment unit re-adjusts the adjusted focus position to a focus position where an error rate of the address information during actual data recording is equal to or less than a predetermined value, and the power adjustment unit adjusts the re-adjusted focus. It is preferable to increase the recording laser beam power according to the position.
[0014]
Also, the present invention is an optical disc apparatus for recording data in a groove of an optical disc in which address information is formed in advance on a land, and detects an optimum address reproduction focus offset for reproducing the address information during data recording. Means, at the time of data recording, means for detecting an optimum recording focus offset for recording data with the best recording quality, and the address information with a focus offset between the optimum address reproduction focus offset and the optimum recording focus offset. It is characterized by comprising means for recording data while reproducing, and means for adjusting the recording laser beam power based on the difference between the focus offset during data recording and the optimum recording focus offset.
[0015]
As described above, according to the present invention, the focus position or the focus offset is set between the optimum value for reproducing the address information and the optimum value for data recording, and the laser beam power is adjusted to compensate for the deterioration of the recording quality. It is. If a difference occurs between the focus position or the focus offset and the optimum position for recording, defocusing is performed to that extent, so that the power of the laser light focused on the recording surface decreases. The decrease in the power of the laser beam causes defective formation of pits to be formed on the recording surface. By compensating for a decrease in laser light power due to defocusing by adjusting (increase) the emitted laser light power itself, both reproduction of address information and recording quality can be achieved.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings, taking a DVD-R drive as an example.
[0017]
FIG. 1 shows a configuration block diagram of an optical disk device according to the present embodiment. The optical disk (DVD-R) 10 is driven to rotate by CAV (or CLV) by a spindle motor 12. As described above, LPP is formed as address information at a predetermined interval in a region (land) between grooves which are information recording tracks on the optical disc 10, and the LPP is detected to determine an address.
[0018]
The optical pickup 14 is arranged to face the optical disk 10 and irradiates a laser beam of recording power to the optical disk 10 to record data, and irradiates a laser beam of reproduction power to reproduce recorded data. At the time of recording, the recording data from the controller 20 is modulated by the encoder 18, and further converted into a drive signal by the LD drive unit 16 to drive the laser diode (LD) of the optical pickup 14. At the time of reproduction, the amount of return light converted into an electric signal by the optical pickup 14 is supplied to the RF signal processing unit 22, further demodulated by the decoder 24, and then supplied to the controller 20 as reproduction data.
[0019]
The RF signal processing unit 22 includes an amplifier, an equalizer, a binarizing unit, a PLL unit, and the like. The decoder 24 demodulates the input binary signal based on the synchronization clock and supplies the demodulated signal to the controller 20 as reproduction data. The reproduced RF signal is also supplied to the pre-pit detection unit 26.
[0020]
The pre-pit detection unit 26 detects an LPP signal component formed on a land adjacent to the groove (land adjacent to the outer periphery of the groove) included in the reproduced RF signal, and supplies the signal component to the controller 20.
[0021]
The controller 20 is configured by a microcomputer or the like, and supplies the recording data to the encoder 18 and supplies the detected pre-pit information to the encoder 18. The encoder 18 modulates the recording data and periodically inserts synchronization information based on the pre-pit detection information to supply a data signal to the LD driving unit 16. Further, the controller 20 calculates an LPP address reproduction rate or an LPP address error rate based on the LPP detection signal from the pre-pit detection section 26, and determines a focus offset and a laser beam power based on the reproduction rate or the error rate.
[0022]
The focus error generator 28 generates a focus error signal based on a signal from the RF signal processor 22. The focus error signal is generated based on a signal from a four-divided detector that converts the amount of return light in the optical pickup 14 into an electric signal. For example, it can be obtained by the difference between the diagonal sums of the four-divided detectors (astigmatism method). After the focus error signal is added to the focus offset from the controller 20 by the adder 30, the focus error signal is supplied to the focus servo 32 to adjust the focus position of the optical pickup 14. The focus position is adjusted by increasing or decreasing the focus offset. Instead of supplying the focus offset signal from the controller 20, a separate focus offset supply unit may be provided and supplied to the adder 30. The offset value from the focus offset supply unit is adjusted by a control signal from the controller 20. The focus offset supply unit can be configured with a memory that stores a plurality of offset values. It should be noted that there is another system that generates a tracking error signal and performs tracking control by tracking servo. However, since this is the same as the conventional system, the description is omitted. As a strategy for recording data, a recording strategy similar to the conventional one can be used. That is, a recording pulse is superimposed on a reproduction level to generate a laser beam of recording power, and recording is performed using a plurality of pulses (multi-pulse) instead of using one recording pulse to form one pit.
[0023]
FIG. 2 shows a basic processing flowchart of the controller 20. First, the controller 20 searches for an optimum recording power Po using a predetermined area (PCA area) of the optical disk 10 by a known OPC (Optimum Power Control) (S1). OPC is a process in which test data is recorded by changing the recording power in a plurality of stages, and the optimum recording power is selected based on the quality (β value, jitter, RF amplitude, etc.) of the reproduced signal obtained by reproducing the test data. It is. The focus (FS) offset used for OPC is set to an appropriate value. After searching for the optimum recording power Po, an optimum recording FS offset FSW that minimizes recording jitter when data is recorded in a groove is searched (S2). This search processing is performed by using the optimum recording power Po selected in S1, and the test data is recorded by changing the FS offset to a plurality of stages, and the FS offset at which the jitter of the reproduced signal of the test data is minimized Is executed by selecting. The FSW obtained by the search is stored in the memory of the controller 20.
[0024]
After searching for the optimum recording focus offset FSW, next, the optimum address reproduction FS offset FSLPP for reproducing the LPP is searched (S3). This search process is executed by changing the FS offset to a plurality of stages, reproducing the LPP, and selecting the FS offset that minimizes the error rate. The FSLPP obtained by the search is stored in the memory of the controller 20.
[0025]
After searching the FSW which is the optimum FS offset for recording and the FSLPP which is the optimum FS offset for reproducing the LPP address, the controller 20 searches for the FS offset FSWL which is actually used at the time of data recording based on these FSW and FSLPP (S4). Specifically, the search is performed by searching for the FSWL between the FSW and the FSLPP, and shifting the FSLPP in the direction of the FSW, or shifting the FSW in the direction of the FSLPP. By setting the FSWL between the FSW and the FSLPP, a focus position can be obtained in consideration of both the recording quality and the address reproduction rate. However, as described above, the data recording quality deteriorates to some extent.
[0026]
Therefore, the controller 20 not only searches for the FSWL but also adjusts the optimum recording power Po selected in S1 in order to compensate for the deterioration of the data recording quality accompanying this search (S5). . Specifically, Po is increased to compensate for the deterioration of the recording quality. As a result of setting the FSWL in S4, the focus position is set to a position deviated from the optimum position for data recording, so that the laser beam power on the groove surface is reduced by that amount. The controller 20 increases the recording power Po in order to compensate for the decrease in laser beam power due to such defocus. The amount of increase is set according to, for example, the amount of deviation from the FSW, that is, the amount of defocus from the optimal focus position during data recording. As described above, data is recorded while demodulating the LPP address with the laser light power and FSWL that have been increased and adjusted. It should be noted that the laser light power is readjusted in conjunction with the shift of the FS offset.
[0027]
Hereinafter, the processing flowchart of the present embodiment will be described in more detail.
[0028]
FIG. 3 shows a detailed processing flowchart of S1 to S4 in FIG. That is, this is a process of setting the actual focus offset at the time of data recording between the optimal focus offset for recording and the optimal focus offset for LPP reproduction. First, the controller 20 determines the optical disk 10 by acquiring the disk information of the optical disk 10 (S101). The disc is determined based on, for example, recording speed, strategy information, FS offset for reproduction, manufacturer, and the like. These are determined by reading data that has been formed at a predetermined position on the optical disc 10 in advance.
[0029]
Next, the recording power is fixed to a certain value (this initial recording power may also be acquired in S101), and the test data is recorded in the test area of the optical disk 10 by changing the FS offset to a plurality of stages (S102). The recorded test data is reproduced with the reproduction FS offset acquired in S101, and the FS offset of the test data that provides the maximum RF amplitude is set in FSW1 (S103). This FSW1 is considered as an optimum recording FS offset when recording data at a certain recording power (not the optimum recording power). Actually, it is necessary to optimize the recording power, and the optimal recording FS offset may change with the optimization of the recording power.
[0030]
Next, the controller 20 executes the OPC using the FSW1 set in S103, and selects the optimum recording power Po (S104). That is, the FS offset is set to FSW1, the force position is fixed, the recording power is changed to a plurality of levels, test data is recorded, and the test data is reproduced by the reproduction FS offset set in S101, and the RF signal of the RF signal is reproduced. The recording power at which the β value becomes a desired value is selected as the optimum recording power Po. The recording power that minimizes the jitter of the reproduction RF signal may be set as the optimum recording power Po.
[0031]
After selecting the optimum recording power Po by OPC, the test data is recorded by changing the FS offset to a plurality of stages again using this Po, and a reproduction signal of the test data is obtained, and the LPP error rate during recording is measured ( S105). The LPP error rate is calculated based on the detection result from the pre-pit detection unit 26, and is calculated, for example, in block units (16 sector units). It counts how many of the 16 blocks the address can be reproduced. For example, if the LPP address can be reproduced in 10 of the 16 blocks, the error rate is about 38%. The controller 20 sets the FS offset at which the minimum jitter is obtained as FSW and the FS offset at which the minimum LPP error is obtained as FSLPP (S106). As described above, the optimum recording focus offset FSW for data recording and the optimum address reproduction FS offset FSLPP for LPP reproduction are set. After setting the two FS offsets, the controller 20 sets FSWL, which is the actual FS offset at the time of data recording, between FSW and FSLLP. Specifically, the controller 20 selects the FS offset having the address error rate smaller than the predetermined value A and closest to the FSW as the FSWL (S107).
[0032]
FIG. 4 schematically shows the process of S107. In the figure, the horizontal axis indicates the FS offset, the left vertical axis indicates the recording jitter, and the right vertical axis indicates the LPP address error. The jitter characteristics and LPP error characteristics are the same as in FIG. The FSWL closest to the FSW is selected from among the FS offsets in which the LPP address error rate is equal to or less than the allowable value A (indicated by a broken line in the figure: A is 20%, for example). Is set. The FSWL can be said to be FSLPP shifted in the direction of FSWP or FSW shifted in the direction of FSLPP. The FSWL is a value that enables the LPP to be reproduced at the address error rate A and that can record data with a smaller jitter than the FSLPP.
[0033]
On the other hand, although FSWL has less recording jitter than FSLPP, recording jitter is deteriorated as compared with FSW, and data is not recorded under the best conditions. This is because the FSWL is located at a position shifted to the FSLPP side from the FSW, so that the laser beam power on the groove surface is reduced by that amount and the recording film cannot be sufficiently heated.
[0034]
FIG. 5 shows a change in the RF amplitude when the FS offset is changed. When the FS offset is FSW, the RF amplitude becomes maximum, and the RF amplitude decreases as the FS offset shifts. Assuming that the RF amplitudes when the FS offset is FSW, FSWL, and FSLPP are α, β, and γ, respectively, α>β> γ decreases as illustrated. Therefore, the controller 20 re-adjusts the optimum recording power Po with the shift of the FS offset, and suppresses the deterioration of the recording quality. The increase amount of the recording power Po is set according to the shift amount of the FSWL from the FSW. For example, the shift amount is increased by 5% for 0.1 μm. The increase ratio per unit shift amount is appropriately adjusted. This compensates for a decrease in laser light power on the groove surface due to defocus.
[0035]
It is also preferable to increase and adjust the recording power Po while monitoring the change in the LPP address error rate, instead of simply adjusting the recording power Po in accordance with the deviation of the FS offset from the optimum recording position. That is, although the FSWL is set to be the optimum FS offset in the test area of the optical disk 10, the optimum FS offset may change due to characteristic variations in the optical disk surface. In such a case, while setting FSWL as an initial value, the LPP error rate is appropriately monitored during actual data recording, and the FS offset is sequentially changed so that the address error rate becomes a predetermined value or less. At this time, the recording power is also sequentially adjusted according to the change of the FS offset.
[0036]
FIG. 6 shows a processing flowchart of the laser light power adjustment. First, data recording is started with the FSWL set in S107, and the LPP error rate during recording is measured constantly or periodically (S109). If the number of errors is within the predetermined allowable range (NO in S110), the FS offset is maintained at FSWL, and the data recording is continued. On the other hand, if the number of errors exceeds the allowable value (YES in S110), the FS offset is further shifted from FSWL to the FSLPP side by a certain amount (S111). By shifting to the FSLPP side, the LPP address error rate is improved to be equal to or less than the allowable value. However, if the FS offset is shifted to the FSLPP side too much, the spot shape of the laser beam changes, resulting in a remarkable deterioration of the recording quality and cannot be compensated for by increasing the laser beam power. Therefore, it is desirable to provide a fixed limit value for the shift amount of the FS offset, that is, the shift amount from the FSW to the FSLPP, and determine whether the limit value has been reached (S112). If the limit value has not yet been reached, the controller 20 supplies a control signal to the LD drive unit 16 to increase the laser light power in accordance with the shift amount of the FS offset (S113). On the other hand, when the laser beam power reaches the limit value, predetermined abnormal processing is performed because the laser beam power cannot cope with the limit value (S114). The abnormal processing is, for example, interruption of recording. The increase of the laser beam power in S113 is adjusted, for example, so as to increase by 5% per 0.1 μm of the shift amount as described above.
[0037]
Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications can be made.
[0038]
For example, in the present embodiment, the laser light power is increased from the initial Po in accordance with the deviation of the FS offset from the optimum recording offset, that is, Δ = (FSWL−FSW), thereby suppressing the deterioration of the recording quality. May be set again, the OPC may be performed again, and the laser light power at which the reproduced signal quality is the best may be reset. In this case, the reset laser light power is higher than the initial Po.
[0039]
【The invention's effect】
As described above, according to the present invention, it is possible to maintain the recording quality of data while reliably reproducing address information.
[Brief description of the drawings]
FIG. 1 is a configuration block diagram of an optical disk device.
FIG. 2 is a basic processing flowchart of the embodiment.
FIG. 3 is a detailed processing flowchart (part 1) of the embodiment.
FIG. 4 is a graph showing a relationship between an FS offset, a recording jitter, and an LPP address error.
FIG. 5 is a graph showing a relationship between FS offset and RF amplitude.
FIG. 6 is a flowchart (part 2) of a detailed process according to the embodiment;
FIG. 7 is an explanatory diagram showing a relationship between an LPP and synchronization information.
FIG. 8 is an explanatory diagram showing a relationship between an LPP, synchronization information, and a frame.
FIG. 9 is a graph showing the relationship between FS offset, recording jitter, and LPP address error.
[Explanation of symbols]
10 optical disk, 12 spindle motor, 14 optical pickup, 16 LD drive unit, 18 encoder, 20 controller, 22 RF signal processing unit, 24 decoder, 26 pre-pit detection unit, 28 focus error generation unit, 30 adder, 32 focus servo.

Claims (6)

An optical disc device for recording data on an optical disc on which address information is formed in advance, comprising:
Focus adjustment means for adjusting the focus position between an optimum recording focus position for recording data and an optimum address reproduction focus position for reproducing the address information,
An optical disc device, comprising: a power adjusting unit that adjusts a recording laser beam power in conjunction with the adjustment of the focus position. The device of claim 1,
The optical disc apparatus according to claim 1, wherein the focus adjustment means adjusts the focus position so that an error rate of the address information is equal to or less than a predetermined value. The device according to claim 2,
The optical disk device, wherein the power adjusting unit increases the recording laser beam power in accordance with a difference between the focus position adjusted by the focus adjusting unit and the optimum recording focus position. The device of claim 1,
An optical disk device, wherein the power adjustment unit records test data at a focus position obtained by the adjustment by the focus adjustment unit, and adjusts the recording laser light power based on a reproduction signal quality of the test data. . The device of claim 1,
The focus adjustment means adjusts the focus position prior to actual data recording, and
Means for detecting an error rate of the address information during actual data recording at the adjusted focus position,
The focus adjustment unit re-adjusts the adjusted focus position to a focus position at which an error rate of the address information during actual data recording is equal to or less than a predetermined value,
The optical disk device, wherein the power adjusting unit increases the recording laser beam power in accordance with the readjusted focus position. An optical disc device for recording data in a groove of an optical disc in which address information is formed in advance on a land,
Means for detecting an optimum address reproduction focus offset for reproducing the address information during data recording;
Means for detecting an optimum recording focus offset for recording data with the best recording quality during data recording;
Means for recording data while reproducing the address information at a focus offset between the optimal address reproduction focus offset and the optimal recording focus offset,
An optical disc device comprising: means for adjusting recording laser beam power based on a difference between a focus offset during data recording and the optimum recording focus offset.

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