JP2002183960A - Optical information recording and reproducing device and optical information recording method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent degradation in recording characteristics by the variation and fluctuation in the spot diameter of an optical pickup. SOLUTION: The spot diameter of a laser beam is measured and recording pulses are modulated by correcting a recording strategy according to the measured spot diameter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information recording method, and more particularly to an optical information recording method for performing a strategy correction in consideration of a variation in a spot diameter of a laser beam.

[0002]

2. Description of the Related Art In recent years, as a large-capacity recording medium, CD-R
(Compact Disk-Recordable), CD-RW (Rewritabl)
e) and other write-once optical discs and phase-change optical discs are attracting attention. Recently, shorter wavelength semiconductor lasers as laser light sources, smaller spot diameters using high NA objective lenses, and the use of thinner substrates have been adopted. DVD (Digital Versatile Dis
k) -ROM, DVD-R (Recordable), DVD-R
Optical disks such as AM are also in the stage of 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 to record information. As the recording waveform,
For example, a recording pulse waveform generated based on a recording modulation method such as EFM (Eight to Fourteen Modulation) modulation is used.

However, simply controlling the laser beam on the basis of the recording pulse waveform causes problems such as shape distortion and misalignment of the recording mark due to residual heat, causing jitter and distortion in the reproduced RF signal. appear.

[0005] Therefore, a pit is formed by irradiating a laser beam using a write pulse (this compensation means is called a strategy) which appropriately compensates a recording pulse waveform generated based on EFM modulation or the like, thereby forming a good reproduced signal. I'm trying to get

For example, there has been proposed a method in which one pulse in a recording pulse waveform is converted into a multi-pulse composed of a pulse train formed by a combination of a leading pulse and a plurality of successive pulses. At this time, it has 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.

Further, a strategy for shortening a pulse width corresponding to at least the shortest recording mark in a recording pulse waveform has been proposed.

When recording on an optical disk, it is necessary to properly control the recording power. Here, the optimum value of the recording power depends on the type of medium, linear velocity, ambient temperature, etc. It changes with.

Therefore, the optical information recording / reproducing apparatus is provided with a table storing setting conditions in which the type (manufacturer, model number, etc.) and the linear velocity of the optical disk correspond to the optimal strategy, and the ID code of the mounted optical disk. The optimal strategy for the inserted optical disk is read from the table by specifying the type of the optical disk by reading the data, and the recording speed magnification is identified by the user, and the optimal strategy is set.

[0010]

However, in the table storing the above-mentioned conventional setting conditions, the recording characteristics in the case where the spot diameter fluctuation factors such as spot diameter variation, mechanical accuracy, and aging change of each optical pickup overlap are overlapped. Can not cope with the deterioration of

It is an object of the present invention 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]

In order to achieve the above-mentioned object, the present invention modulates a recording pulse signal corresponding to desired information based on a recording strategy set in advance under various conditions. In an optical information recording / reproducing apparatus for recording information by irradiating an optical information recording medium with a beam light controlled based on the recorded recording pulse signal, the laser beam is formed by condensing the laser beam on the optical information recording medium. Spot diameter measuring means for measuring the spot diameter of the beam spot; strategy correction amount storage means set as a function of a recording mark length forming a correction amount of the recording strategy corresponding to the spot diameter; and strategy correction amount storage means Recording strategy correction means for making a correction corresponding to the spot diameter measured by the spot diameter measurement means to the recording strategy based on Characterized in that it has a.

According to the present invention, a beam pulse modulated based on a recording pulse signal which modulates a recording pulse signal corresponding to desired information based on a preset recording strategy under various conditions, and is controlled based on the modulated recording pulse signal. In the optical information recording method of recording information by irradiating the optical information recording medium with a laser beam, measuring the spot diameter of a beam spot formed by condensing the laser beam on the optical information recording medium, The recording strategy is modulated based on a correction amount of the recording strategy set in advance as a function of a length of a recording mark to be formed correspondingly.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the optical information recording method according to the present invention will be described below in detail with reference to the accompanying drawings.

In this embodiment, a case where the optical information recording medium is constituted by an optical disk will be described.

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 more the strategy correction amount. Is also getting bigger.

FIG. 1 is a diagram showing the schematic configuration of an optical disk recording / reproducing apparatus according to an embodiment of the present invention.

The optical disk recording / reproducing apparatus shown in FIG. 1 is configured such that when the optical disk 4 is inserted from a disk insertion opening (not shown),
The disk 4 is rotated at a constant linear speed by the spindle motor 11, and information is recorded and reproduced on the disk 4 by the optical pickup 13.

The rotation speed of the disk 4, that is, the rotation speed of the spindle motor 11, is detected by a frequency signal generator (FG) 12 and managed by the controller 10.

The input data is input to the recording signal generation circuit 16 by E.
The signal is FM-modulated, and further modulated by a recording signal correction unit 15 in accordance with an instruction from a controller 10 described later, to be a recording pulse signal.

This recording pulse signal is supplied to the LD driver 14
The LD driver 14 controls a laser diode (not shown) included in the optical pickup to irradiate the optical disc 4 with pulsed laser light synchronized with the input recording pulse signal.

The 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 the optical pickup 13 Used for focus control and tracking control.

Further, the read signal amplified by the head amplifier 17 is input to a read signal processing circuit 18, which reads absolute time information ATIP (AT) as recording position data from the input read signal. Is extracted, and various processes are applied to the read signal to output the read signal as a reproduced signal.

The absolute time information ATIP extracted by the read signal processing circuit 18 is a CLV (Constant Linear Velocit).
y) input to the control circuit 23, and the CLV control circuit 23
The rotation of the spindle motor 11 is controlled at a constant linear speed based on the input absolute time information ATIP.

The optical pickup 13 has a focus control function and a tracking control function. The focus control function and the tracking control function are controlled by a focus / tracking control circuit 20.

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.

FIG. 2 is a control block of the recording control by the controller 10 of FIG.

In FIG. 2, the basic strategy storage unit 33
Stores the optimum basic recording strategy (modulation amount, recording power, etc.) according to the combination of the disc type, linear velocity, and recording speed magnification.

The basic strategy correction amount storage unit 34
Stores the correction amount of the basic recording strategy corresponding to the spot diameter as a function of the strategy correction amount for the recording mark length for each spot diameter, for example, as shown in FIG.

The strategy selection section 31 reads out a corresponding basic recording strategy from the basic strategy storage section 33 in accordance with information such as the disc type, the linear velocity, and the recording speed magnification of the disc 4 to be inputted.

The disc type can be determined by using, for example, information indicating the disc type among the disc IDs recorded in advance on the optical disc 4. The linear velocity of the disc 4 can be determined, for example. By reading the recording time recorded in the lead-in section, the corresponding linear velocity can be determined.

Further, the recording speed magnification (× 1, × 2, × 4,
..) Are set based on an instruction from the input device 26 by a user or the like.

The spot diameter measuring unit 32 measures the beam spot diameter formed on the disk 4 by the laser light emitted from the optical pickup 13 by, for example, a method described later in detail.

The strategy selection section 31 reads the corresponding correction amount from the basic strategy correction amount storage section 34 in accordance with the beam spot diameter measured by the spot system measurement section 32, and the recording strategy read from the basic strategy storage section 33. Is corrected.

The laser control means 33 controls the recording signal correction section 15 based on the recording strategy selected and corrected by the strategy selection section 31 to adjust the length of the recording mark forming portion or space forming portion of the recording signal. The modulation is performed, and the laser power is controlled by controlling the LD driver 14.

Next, the spot diameter measuring method will be described by way of an example.

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.

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).

Next, under the control of the focus / tracking control circuit 20, the optical pickup 13 appropriately focuses the laser beam on the head of the spot measurement pit pattern recorded in the spot measurement area of the optical disk 4. Then, reading of the RF signal is started (step 102).

The pit pattern for spot measurement 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 area. This is an area where a pit pattern is formed.

The RF signal read from the spot measurement area is input to the head amplifier 17 and also directly to the spot diameter specifying unit 32.

The spot diameter specifying section 32 first differentiates the input RF signal to generate a differentiated waveform (step 10).
3) Extract a differential waveform corresponding to the edge waveform of the RF signal from the generated differential waveform (step 104).

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 number of differential waveforms is twice the number of pits of the entire spot measurement pit pattern. Are extracted in step 605, and therefore, the extracted differential waveform is averaged and used for the next processing.

As a method of averaging the differential waveform,
The following three methods are applicable.

1) Only the differential waveform corresponding to the leading edge is averaged.

2) Only the differential waveform corresponding to the trailing edge is averaged.

3) Averaging is performed using both the differentiated waveform corresponding to the leading edge and the differentiated waveform corresponding to the trailing edge.

Since the polarity of the differential waveform corresponding to the trailing edge is reversed, the waveform of the absolute value is averaged.

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 detected two points. The effective spot diameter of the laser beam emitted from the optical pickup 13 is calculated based on the time between points and the rotation speed of the optical disk 4 obtained from the FG 12 (step 105).

[0050]

As described above, according to the present invention, a recording strategy is corrected in accordance with a measured spot diameter to modulate a recording pulse, so that spot diameter variation, optical pickup accuracy, and spot change due to aging change. Even when spot diameter fluctuation factors such as a change in diameter overlap and the spot diameter largely shifts, 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 a configuration of an optical disc recording / reproducing apparatus according to the present invention.

FIG. 2 is a block diagram showing an example of a configuration of a recording control unit of the optical disc recording / reproducing apparatus of 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]

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Isao Matsuda 6-16-20 Ueno, Taito-ku, Tokyo Taiyo Denki Co., Ltd. (72) Inventor Shino Sekiguchi 6-16-20 Ueno, Taito-ku, Tokyo Taiyo Denki Co., Ltd. F-term (reference) 5D090 AA01 BB03 BB05 CC01 EE03 KK20

Claims (2)

[Claims] 1. A recording pulse signal corresponding to desired information is modulated based on a preset recording strategy, and a light beam controlled based on the modulated recording pulse signal is irradiated on an optical information recording medium to produce information. An optical information recording / reproducing apparatus for recording the laser beam; a spot diameter measuring means for measuring a spot diameter of a beam spot formed by condensing the laser beam on the optical information recording medium; and forming the spot on the optical information recording medium. A strategy correction amount storage unit in which a correction amount of the recording strategy corresponding to the spot diameter is set as a function of a recording mark length; and the recording strategy is measured by the spot diameter measurement unit based on the strategy correction amount storage unit. An optical information recording / reproducing apparatus comprising: a recording strategy correction unit for performing correction according to a spot diameter. 2. A method for modulating a recording pulse signal corresponding to desired information based on a preset recording strategy, and irradiating a light beam controlled based on the modulated recording pulse signal onto an optical information recording medium to obtain information. In the optical information recording method for performing the recording, the spot diameter of a beam spot formed by condensing the laser beam on the optical information recording medium is measured, and the spot diameter is formed on the optical information recording medium in accordance with the spot diameter. An optical information recording method, wherein the recording strategy is modulated based on a correction amount of the recording strategy preset as a function of a recording mark length to be recorded.