JP3755401B2 - Optical information recording / reproducing apparatus and optical information recording method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical information recording method, and more particularly to an optical information recording method in which strategy correction is performed in consideration of variations in the spot diameter of a laser beam.
[0002]
[Prior art]
In recent years, write-once optical disks such as CD-R (Compact Disk-Recordable) and CD-RW (Rewritable), phase change optical disks, and the like have attracted attention as large-capacity recording media. Recently, semiconductor lasers as laser light sources are used. DVD (Digital Versatile Disk) -ROM, DVD-R (Recordable), etc., which enabled further large-capacity recording by shortening the wavelength of light, reducing the spot diameter with a high NA objective lens, and adopting a thin substrate, etc. Optical discs such as DVD-RAM are also in practical use.
[0003]
In any of the optical discs, an optical information recording / reproducing apparatus including an optical pickup optical system using a semiconductor laser as a light source is used for recording information, and a general recording waveform for recording information on the optical disc is used. For example, a recording pulse waveform generated based on a recording modulation method such as EFM (Eight to Fourteen Modulation) modulation is used.
[0004]
However, simply controlling the laser beam based on the recording pulse waveform causes problems such as shape distortion and positional deviation in the recording mark due to residual heat, and jitter and distortion in the reproduced RF signal.
[0005]
Therefore, a pit is formed by irradiating a laser beam using a write pulse (this compensation means is called a strategy) appropriately compensated for a recording pulse waveform generated based on EFM modulation or the like, so as to obtain a good reproduction signal. I have to.
[0006]
For example, a method has been proposed in which one pulse in a recording pulse waveform is converted into a multi-pulse composed of a pulse train composed of a combination of a head pulse and a plurality of subsequent continuous pulses. At this time, it has also been proposed to change the pulse width of the leading pulse by a combination of the recording mark length and the space length immediately before the recording mark.
[0007]
Furthermore, a strategy for shortening the pulse width corresponding to at least the shortest recording mark in the recording pulse waveform has also been proposed.
[0008]
By the way, when recording on an optical disc, it is necessary to correctly control the recording power. Here, the optimum value of the recording power varies depending on the type of medium, linear velocity, ambient temperature, and the like. .
[0009]
Therefore, the optical information recording / reproducing apparatus is provided with a table storing setting conditions in which the optical disk type (manufacturer, model number, etc.) and linear velocity are associated with the optimum strategy, and reads the ID code of the mounted optical disk. By specifying the type of the optical disc by the above and specifying the recording speed magnification by the user designation, the optimum strategy for the inserted optical disc is read from the table and the optimum strategy is set.
[0010]
[Problems to be solved by the invention]
However, the table storing the conventional setting conditions cannot cope with the deterioration of the recording characteristics when the spot diameter variation factors such as the optical pickups, the mechanical accuracy, and the aging change overlap.
[0011]
Accordingly, an object of the present invention is to provide an optical information recording / reproducing apparatus and an optical information recording method capable of easily obtaining a recording strategy suitable for each optical information recording medium.
[0012]
[Means for Solving the Problems]
To achieve the above object, this invention relates to an optical laser beam is controlled based on a desired modulated based on the recording strategy is preset recording pulse signal corresponding to the information, recording pulse signal said modulated In an optical information recording / reproducing apparatus for recording information by irradiating an information recording medium, spot diameter measuring means for measuring the spot diameter of the laser beam formed by condensing the laser beam on the optical information recording medium; Strategy correction amount storage means for setting the correction amount of the recording strategy as a function of the recording mark length formed on the optical information recording medium corresponding to the spot diameter, and the spot diameter measured by the spot diameter measuring means correspondingly ingredients and recording strategy correction means for correcting the write strategy correction amount set in the strategy correction amount storage means Characterized in that it.
[0013]
Further, the present invention is modulated based on the recording strategy is preset recording pulse signal corresponding to the desired information, a laser beam is controlled to irradiate the optical information recording medium based on the recording pulse signal said modulated In the optical information recording method for recording information, the correction amount of the recording strategy as a function of the recording mark length formed on the optical information recording medium is stored in the strategy correction amount storage means corresponding to the spot diameter of the laser beam. set, the spot diameter of the laser beam of the laser beam is formed by focusing on the optical information recording medium was measured by the spot diameter measuring means, wherein in response to the measured spot size at the spot diameter measuring means the recording strategy correction means said recording strategy correction amount set in strategy correction amount storage means and said correcting That.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of an optical information recording method according to the present invention will be described below in detail with reference to the accompanying drawings.
[0015]
In this embodiment, the case where the optical information recording medium is composed of an optical disk will be described.
[0016]
FIG. 3 is a graph showing the strategy correction amount corresponding to the spot diameter as a function of the recording mark length to be formed. The larger the spot diameter and the shorter the recording mark length, the larger the strategy correction amount. ing.
[0017]
FIG. 1 is a diagram showing the schematic configuration of an optical disc recording / reproducing apparatus according to an embodiment of the present invention.
[0018]
In the optical disk recording / reproducing apparatus of FIG. 1, when the optical disk 4 is inserted from a disk insertion port (not shown), the spindle motor 11 rotates the disk 4 at a constant linear velocity, and the optical pickup 13 records and reproduces information on the disk 4. .
[0019]
Here, the rotational speed of the disk 4, that is, the rotational speed of the spindle motor 11 is detected by the frequency signal generator (FG) 12 and managed by the controller 10.
[0020]
The input data is EFM modulated by the recording signal generation circuit 16 and further modulated by an instruction from the controller 10 (to be described later) by the recording signal correction unit 15 to become a recording pulse signal.
[0021]
The recording pulse signal is input to the LD driver 14, and the LD driver 14 controls a laser diode (not shown) included in the optical pickup so that a pulsed laser beam synchronized with the input recording pulse signal is applied to the optical disk 4. Irradiate.
[0022]
A signal read from the disk 4 is amplified by a head amplifier 17, and a focus error (FE) signal and a tracking error (TE) signal are input to a focus / tracking control circuit 20, and focus control and optical pickup 13 are controlled. Used for tracking control.
[0023]
Further, the read signal amplified by the head amplifier 17 is input to the read signal processing circuit 18, and the read signal processing circuit 18 extracts absolute time information ATIP (AT) as recording position data from the input read signal. Further, the read signal is subjected to various processes and output as a reproduction signal.
[0024]
The absolute time information ATIP extracted by the read signal processing circuit 18 is input to a CLV (Constant Linear Velocity) control circuit 23. The CLV control circuit 23 controls the spindle motor 11 to linear velocity based on the input absolute time information ATIP. The rotation is controlled at a constant level.
[0025]
The optical pickup 13 has a focus control function and a tracking control function, and the focus control function and the tracking control function are controlled by the focus / tracking control circuit 20.
[0026]
The optical pickup 13 is configured to be movable in the radial direction of the disk 4 by a feed motor 22, and the feed motor 22 is controlled by a feed control circuit 21.
[0027]
FIG. 2 is a control block of recording control by the controller 10 of FIG.
[0028]
In FIG. 2, a basic strategy storage unit 33 stores an optimal basic recording strategy (modulation amount, recording power, etc.) according to the combination of the disc type, linear velocity, and recording velocity magnification.
[0029]
Further, the basic strategy correction amount storage unit 34 stores the basic recording strategy correction amount according to the spot diameter as a function of the strategy correction amount with respect to the recording mark length for each spot diameter as shown in FIG. 3, for example. Yes.
[0030]
The strategy selection unit 31 reads out the corresponding basic recording strategy from the basic strategy storage unit 33 according to information such as the disc type, linear velocity, and recording velocity magnification of the input disc 4.
[0031]
The disc type can be determined using, for example, information indicating the disc type among the disc IDs recorded in advance on the optical disc 4, and the linear velocity is, for example, the lead-in portion of the disc 4 It is possible to determine the corresponding linear velocity by reading the recording time recorded in the.
[0032]
The recording speed magnification (× 1, × 2, × 4,...) Is set based on an instruction from the user or the like on the input device 26.
[0033]
The spot diameter measuring unit 32 measures, for example, a beam spot diameter formed on the disk 4 by the laser beam emitted from the optical pickup 13 by a method described in detail later.
[0034]
The strategy selection unit 31 reads the corresponding correction amount from the basic strategy correction amount storage unit 34 and corrects the recording strategy read from the basic strategy storage unit 33 according to the beam spot diameter measured by the spot system measurement unit 32. .
[0035]
Based on the recording strategy selected and corrected by the strategy selection unit 31, the laser control unit 33 controls the recording signal correction unit 15 to modulate the length of the recording mark formation portion and the space formation portion of the recording signal. At the same time, the laser power is controlled by controlling the LD driver 14.
[0036]
Next, the spot diameter measuring method will be described with an example.
[0037]
FIG. 4 is a flowchart showing an example of the flow of spot diameter measurement control in the optical information recording / reproducing apparatus of FIG.
[0038]
When the optical disc 4 is inserted into the optical disc recording / reproducing apparatus, the feed control circuit 21 controls the feed motor 22 to move the optical pickup 13 to just below the spot measurement area 41 of the optical disc 4 (step 101).
[0039]
Next, the optical pickup 13 appropriately focuses the laser beam on the head portion of the spot measurement pit pattern recorded in the spot measurement area of the optical disc 4 under the control of the focus / tracking control circuit 20. Reading of the RF signal is started (step 102).
[0040]
The spot measurement pit pattern is a pit pattern in which recording marks longer than the predicted spot diameter are formed at intervals longer than the predicted spot diameter, and the spot measurement area is the spot measurement pit pattern. Is a region formed.
[0041]
The RF signal read from the spot measurement area is input to the head amplifier 17 and also directly input to the spot diameter specifying unit 32.
[0042]
First, the spot diameter specifying unit 32 differentiates the input RF signal to generate a differential waveform (step 103), and extracts a differential waveform of a portion corresponding to the edge waveform of the RF signal from the generated differential waveform (step 103). 104).
[0043]
Here, since two differential waveforms corresponding to the front edge and the rear edge are extracted from the RF signal corresponding to one pit, the differential waveform having twice the number of pits of the entire spot measurement pit pattern is obtained in step 605. Therefore, the extracted differential waveform is averaged and used for the next processing.
[0044]
The following three methods can be applied as a method of averaging the differential waveform.
[0045]
1) Only the differential waveform corresponding to the leading edge is averaged.
[0046]
2) Average only the differential waveform corresponding to the trailing edge.
[0047]
3) Averaging is performed using both the differential waveform corresponding to the front edge and the differential waveform corresponding to the rear edge.
[0048]
Since the differential waveform corresponding to the rear edge has the opposite polarity, the waveform of the absolute value is averaged.
[0049]
Next, the spot diameter specifying unit detects two points having a value of 1 / e2 of the peak value of the differential waveform extracted and averaged, and obtains a time between the two detected points. Based on the time and the rotational speed of the optical disk 4 obtained from the FG 12, the effective spot diameter of the laser beam emitted from the optical pickup 13 is calculated (step 105).
[0050]
【The invention's effect】
As described above, according to the present invention, the recording strategy is corrected in accordance with the measured spot diameter to modulate the recording pulse, so that the spot diameter variation, optical pickup accuracy, spot diameter change due to secular change, etc. Even when the spot diameter fluctuation factors are overlapped and the spot diameter is largely deviated, there is an effect that a highly accurate and stable reproduction signal can be obtained.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an example of the configuration of an optical disc recording / reproducing apparatus according to the present invention.
2 is a block diagram illustrating an example of a configuration of a recording control unit of the optical disc recording / reproducing apparatus of FIG. 1. FIG.
FIG. 3 is a graph showing an example of a function of a strategy correction amount with respect to a recording mark length corresponding to a spot diameter.
FIG. 4 is a flowchart showing a flow of spot diameter measurement.
[Explanation of symbols]

Claims (2)

A recording pulse signal corresponding to desired information is modulated based on a preset recording strategy, and information is recorded by irradiating the optical information recording medium with a laser beam controlled based on the modulated recording pulse signal. In an optical information recording / reproducing apparatus,
Spot diameter measuring means for measuring the spot diameter of the laser beam formed by condensing the laser beam on the optical information recording medium;
A strategy correction amount storage means for setting a correction amount of the recording strategy as a function of a recording mark length to be formed on the optical information recording medium, corresponding to the spot diameter ;
A recording strategy correction unit that corrects the recording strategy by a correction amount set in the strategy correction amount storage unit corresponding to the spot diameter measured by the spot diameter measurement unit. Recording / playback device. A recording pulse signal corresponding to desired information is modulated based on a preset recording strategy, and information is recorded by irradiating the optical information recording medium with a laser beam controlled based on the modulated recording pulse signal. In the optical information recording method,
The correction amount of the recording strategy as a function of the recording mark length formed on the optical information recording medium is set in the strategy correction amount storage means corresponding to the spot diameter of the laser beam,
The spot diameter of the laser beam formed by condensing the laser beam on the optical information recording medium is measured by a spot diameter measuring means ,
An optical information recording method , wherein the recording strategy is corrected by the recording strategy correction means with a correction amount set in the strategy correction amount storage means corresponding to the spot diameter measured by the spot diameter measuring means .

Images