JP3782549B2 - Magneto-optical disk drive - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a drive device for a magneto-optical disk recording apparatus, and more particularly to a magneto-optical disk drive apparatus that determines a laser recording output level in a recording operation using a test pattern recorded on the magneto-optical disk.
[0002]
[Prior art]
In general, when recording information on a magneto-optical disk recording apparatus, a laser beam is scanned so as to follow the track direction of a recording track provided on a recording medium, and a light spot is irradiated onto the recording track. Information is being recorded.
[0003]
As a drive control method for performing recording of this magneto-optical disk recording device, a linear velocity constant control method for maintaining a constant linear velocity for scanning a recording track as used in audio recording and video recording, There is a constant rotation speed method used in computers and the like.
[0004]
Japanese Patent Application Laid-Open No. 5-189825 discloses test patterns recorded in advance on a recording medium at a plurality of recording levels, and the amplitudes of signals read from these test patterns are respectively measured. As a result, a recording control method for a magneto-optical disk reproducing apparatus has been proposed in which the recording level at which the read signal amplitude is maximized is set as the laser recording output level for recording on a recording medium.
[0005]
[Problems to be solved by the invention]
In the above-described conventional recording control method, information is recorded on a groove structure track formed of a groove and a land formed on a recording medium, and information is recorded only on one of the groove or land. It was.
[0006]
Therefore, even if the light spot of the recording laser beam protrudes to the adjacent groove that is not the recording track to be recorded, there is a groove or land other than the recording track between the recording track and the adjacent recording groove. The effect on the information recorded on the recording track was small.
[0007]
However, a high recording density is required so that a large amount of information can be recorded on a recording medium of the same size, and a so-called land / groove recording method has been proposed in which recording is performed on both the groove and land tracks. Yes. In this recording method, since there is no groove adjacent to the recording track and the track for recording information is adjacent as in the prior art, if the light spot protrudes, the recording information on the adjacent recording track is affected. .
[0008]
In particular, when erasing data, the effect of the light spot of the erasing laser beam on the information on the adjacent recording track is referred to as cross-erase characteristics. The influence on recorded information is called cross-write characteristics. If these characteristic values are large, fatal data loss will occur.
[0009]
The technique disclosed in Japanese Patent Laid-Open No. 5-189828 discloses a method for obtaining a recording output level capable of sufficiently ensuring a reproduction signal amplitude in a land / groove recording method while keeping a cross erase / cross write characteristic value small. However, judging from this description, there are the following problems.
[0010]
First, the reproduction signal amplitude characteristic obtained by changing the recording output level is difficult to find the peak in order to draw a broad curve even if the curve fitting technique is used. It is conceivable to apply a method in which the median value of two output levels indicating the same attenuation at both ends of the curve is the optimum value of the recording output, but the obtained optimum value indicates the maximum value of the reproduction signal amplitude. However, even if the maximum value is shown, the obtained recording output can sufficiently secure the reproduction signal amplitude with the cross erase / cross write characteristic value kept small in the land / groove recording method. It is not a thing.
[0011]
Second, in the prior art, the recording output level setting and the reading signal amplitude measurement are repeated, a function curve is obtained by a curve fitting technique for the relationship between the recording output and the reading signal amplitude, and further, this function shows a peak for which the function shows a peak. A series of processes for obtaining an output level and determining and determining an optimum output level at the time of recording requires a certain amount of time. During this time, the user is interrupted from accessing the magneto-optical disk drive.
[0012]
Therefore, the present invention utilizes the recording / reproduction characteristics peculiar to the land / groove recording method suitable for high-density recording, and the reproduction signal amplitude in a state where the cross erase / cross write characteristic value is kept small by a short time measurement and processing. It is an object of the present invention to provide a magneto-optical disk drive device that obtains a recording output level that can sufficiently ensure the above.
[0013]
[Means for Solving the Problems]
In order to achieve the above object, the present invention follows a focus error detection optical system and focus servo means for focusing a light spot on a recording surface of a magneto-optical disk, and a light spot following an information track in the magneto-optical disk. In a magneto-optical disk drive apparatus having a tracking error detection optical system and tracking servo means for recording and recording a land and a groove of a magneto-optical disk, the recording of the optical spot with a signal in which a sine wave is superimposed on a sawtooth wave and amplitude modulating means for the use output is amplitude modulated, and means for continuously level variation the recording output of modulated light spots, to the designated target track on the recording medium surface by recording the output of level variations Recording means for recording an arbitrary test pattern, and amplitude of a reproduction signal obtained by reproducing the test pattern on the recording medium surface Detection means for detecting the Envelope, and detecting a minimum value in the amplitude-ene base rope value of the reproduced signal, said recording means from the detection time positions of the outermost minimum value to detect the recording power level written in recorded test pattern A recording output level detection unit; and a recording unit based on the average value by calculating an average value of the plurality of recording output levels obtained by detecting the target track a plurality of times by the detection unit. and recording the output level setting means for setting as a use output level, a to provide a magneto-optical disk drive that immediately Started.
[0014]
The magneto-optical disk drive having the above-described configuration allows writing by selecting a recording output level that can sufficiently secure the reproduction signal amplitude while keeping the cross erase / cross write characteristic value at an arbitrarily small value. It is possible to write data in a state in which sufficient C / N is ensured without damaging the already recorded data without protruding the recording light spot other than that to be recorded.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
First, the outline of the magneto-optical disk drive of the present invention will be described.
FIG. 4 is a diagram showing the relationship between the recording output level and the reproduced read signal amplitude value in the land / groove recording system suitable for the high-density recording system used in the magneto-optical disk drive of the present invention. Here, the horizontal axis represents the recording output level, and the vertical axis represents the read signal amplitude.
[0016]
When the recording output level is relatively small, the reproduced read signal amplitude value tends to increase almost in proportion to the recording output level, but the light spot of the laser beam irradiated on the recording medium that contributes to recording In a state where the diameter is increased and the groove width or land width of the recording track is approached, the tendency of increase in the read signal amplitude reproduced with respect to the recording output level becomes dull and becomes insensitive.
[0017]
This is presumably because there is an optical spot diameter region that does not contribute to the read signal amplitude in the disk radial direction because an inclined structure exists between the groove and the land.
[0018]
In the land / groove recording method, the difference in level between the land and the groove is larger than that of the conventional recording method in order to reduce the influence of the crosstalk characteristic and the cross race / cross write characteristic.
[0019]
The insensitive characteristic region shown in FIG. 4 is a region where the reproduction signal amplitude does not increase even though the recording output is increased. This insensitive characteristic region is considered to be generated due to a large step in the structure between the land and the groove.
Obtaining the recording output level exhibiting this insensitive characteristic results in obtaining the optimum recording output level that is less affected by the cross erase / cross write characteristic and can sufficiently secure the reproduction signal amplitude.
[0020]
Therefore, in the present invention, a component that amplitude-modulates the recording output level, a component that varies the average value of the modulated recording output level, and a component that detects the amplitude envelope of the reproduction signal are provided. Thus, test writing is performed on the tracks on the recording medium continuously with different recording output levels, that is, a test pattern is formed, and the reproduction signal amplitude from the test pattern is measured. The insensitive area shown can be found.
[0021]
In this trial writing, the recording output level may be different between the land area and the group area.
Since the recording output level in this area is a recording output level that can sufficiently secure the reproduction signal amplitude with the cross erase / cross write characteristic value kept small, the data already recorded on the adjacent recording track is damaged. It is possible to write data without giving it and with sufficient C / N secured.
[0022]
Also, as a test writing method in which the recording output level continuously fluctuates on the track on the recording medium surface, the recording output is modulated by a signal in which a sine wave is superimposed in a sawtooth shape, so that recording is performed each time. Thus, the process of measuring the re-signal amplitude by changing the output level for recording can be performed only once, and as a result, the optimum recording output level can be obtained in a short time.
[0023]
Also, a component for detecting the recording output level that minimizes the amplitude envelope value of the reproduction signal is provided, and an increase function is obtained by obtaining a so-called differential gain characteristic in the recording output level versus the read signal amplitude characteristic. In order to make the portion where the inclination has decreased, the recording signal amplitude can be sufficiently secured with a simple configuration and with a short processing time and a small cross erase / cross write characteristic value. Output level can be set.
[0024]
Next, FIG. 1 shows a configuration example of an embodiment of a magneto-optical disk drive device according to the present invention. In FIG. 1, only the characteristic configuration (internal structure of the optical pickup) is shown for easy understanding of the present invention, and the accompanying magneto-optical disk and mechanical structure are omitted.
[0025]
Here, it is assumed that the pickup mechanism of the magneto-optical disk drive apparatus according to the present invention has the following functions.
(1) Output a servo PD (Photo Diode) output necessary to generate a focus error signal and a tracking error signal.
(2) A focus actuator and a tracking actuator are provided for causing the light spot to accurately follow the recording track on the recording medium surface.
(3) A feed mechanism is provided for positioning the optical pickup on the recording track on the medium surface with rough accuracy.
(4) For a front monitor for taking out a part of light emitted from an LD (Laser Diode) and detecting the output level in order to set the output level of the light spot irradiated on the recording medium surface to a target value. Output PD output.
(5) A control power supply for generating an LD current input for current-driving an LD serving as a light source is provided.
(6) An RF signal detection PD for detecting the recorded magneto-optical signal and sending it to the RF head amplifier at the next stage is provided.
[0026]
Next, the configuration of the pickup mechanism portion of the magneto-optical disk drive device of this embodiment shown in FIG. 1 will be described.
This pickup mechanism unit optically reads information from a storage medium, inputs an optical pickup unit 1 that outputs an electrical signal, and a servo PD output signal 2 from the optical pickup unit 1 to input a focus and tracking actuator. A focus / tracking / feed servo circuit 3 for driving the servo circuit 3, an arithmetic processing and control circuit 4 for controlling all of the servo circuit 3, and an amplifying PD output signal 5 for RF signal detection from the optical pickup unit 1. An RF head amplifier 6, an envelope detection circuit 7 that measures the amplitude value of the RF signal output from the RF head amplifier 6 by an envelope detection circuit configuration, an arithmetic processing and control circuit 4 that performs arithmetic processing described later, The front monitor PD output signal 8 output from the pickup unit 1 is converted from current to voltage, and the optical signal is picked up. A forward monitor I / V circuit 9 that generates a reference signal for calculating a target value of a drive current supplied to an LD (not shown) in the up unit 1, an LD driver 10 that is driven and controlled by an arithmetic processing and control circuit 4, The data signal instructed from the arithmetic processing and control circuit 4 is converted into a light emission pattern suitable for recording, and sent to the LD driver 10, and the light output of the light spot is amplitude-modulated to produce an LD. An amplitude modulation signal generator 13 to be sent to the driver 10 and a sawtooth shape for modulating the average value level of the amplitude-modulated signal in a sawtooth shape and sending it to the LD driver 10 under the control of the arithmetic processing and control circuit 4. And a wave generator 14.
[0027]
In the optical pickup mechanism unit configured as described above, the servo PD output signal 2 output from the optical pickup unit 1 is input to the focus / tracking / feed servo circuit 3 controlled by the arithmetic processing and control circuit 4, A focus and tracking actuator (not shown) in the optical pickup unit 1 is driven.
[0028]
Then, the RF signal detection PD output signal 5 from the optical pickup unit 1 is amplified by current-voltage conversion by an RF head amplifier 6 and input to the envelope detection circuit 7 in the next stage, and the amplitude value of the RF signal is subjected to envelope detection. After the measurement with the one-path configuration, the arithmetic processing and control circuit 4 is manually operated to perform the arithmetic processing described later.
[0029]
The front monitor PD output signal 8 output from the optical pickup unit 1 is converted into a current / voltage by the front monitor I / V circuit 9 and is output to an LD (not shown) in the optical pickup unit 1 by the arithmetic processing and control circuit 4. This is used as a reference signal for calculating the target value of the drive current to be supplied.
[0030]
The LD driver 10 receives a target value signal 11 as a reference value necessary for determining the light output level of the laser beam emitted from the optical pickup unit 1 from the arithmetic processing and control circuit 4. In addition, when writing data, it is necessary to cause the LD to emit light with a pulse waveform corresponding to the data to be written. Therefore, the data signal instructed from the arithmetic processing and control circuit 4 is emitted by the write pulse generator 12 so as to be suitable for recording. It is converted into a pattern and sent to the LD driver 10.
[0031]
Data modulation methods used in this embodiment include general pit position modulation (PPM) and pulse width modulation (PWM). Among these, the PPM can demodulate data if the specific position (for example, peak position of the waveform) of the pulse signal in the reproduction signal is accurately detected, so that the pit mark formed on the surface of the recording medium The shape does not have to be precisely arranged. However, in PWM, since the rising position and falling position of the pulse signal in the reproduction signal become data information, the information on the rising position and the falling position of the reproduction signal is required to be accurate. The shape of the pit mark formed on the top must be in order.
[0032]
Therefore, in PWM, for the purpose of adjusting the shape of the pit mark, it is widely used to realize this by making a multi-pulse for one recording mark and making the heat diffusion effect constant. Therefore, the write pulse generator 12 at the time of PWM generates a pulse train in which one pulse is a multi-pulse.
[0033]
Next, FIGS. 2A to 2C show characteristics of the peak value of the output level of the light spot emitted from the optical pickup unit 1 described above. Here, the fine sine wave-like undulation is generated because the peak value of the recording pulse is modulated by the amplitude modulation signal generator 13. Specifically, it is obtained by detecting the received light signal of the light spot with an envelope (envelope).
[0034]
In addition, the signal waveform of the light spot shown in FIG. 2A is actually a signal having a density of about 10 light pulses per cycle as shown in FIG. In this way, it is superimposed on a certain level of assist output (about the output level of the reading light spot). Here, the assist output is a value at a certain level set in order to shorten the rise time to the peak on the write power. Further, the recording by this light spot is recorded on the information track from point A to point B as shown in FIG. 6B, for example.
[0035]
Since the output level of the recording light spot changes depending on the waveform of the recording pulse, the output level of one recording pulse takes a value from zero or a low output level close to zero to a peak value, but envelope detection is required. Thus, the characteristics shown in FIG. 2A are obtained. FIG. 2B shows characteristics obtained from the RF signal detection PD output signal 5 output from the optical pickup unit 1 by the same method as shown in FIG. Here, for easy comparison between the RF signal detection PD output signal 5 and the recording output level, the horizontal axis of FIG. 2B is shown on the same scale as FIG. 2A.
[0036]
In FIG. 4, the relationship between the recording output and the reproduction signal amplitude has been described. When the light spot diameter on the recording medium contributing to recording approaches the groove width or land width as a recording track, the recording output level Since the read signal amplitude of the reproduced signal has a slow increasing tendency and exhibits insensitive area characteristics, as shown in FIG.
[0037]
FIG. 2C is a diagram in which the envelope in FIG. 2B is extracted and rewritten.
The concave portion m shown in FIG. 2C indicates a state in which the light spot diameter on the recording medium contributing to recording approaches a groove width or a land width which is a recording track. This indicates that this area has been recorded at the optimum recording output level, so that subsequent recording may be performed using the recording output level in this area.
[0038]
Next, with reference to the flowchart shown in FIG. 3, the operation of the pickup mechanism unit of the magneto-optical disk drive apparatus of this embodiment will be described. Here, the operation part related to the gist of the present invention will be described, and the other operations before and after that will be omitted.
[0039]
First, the medium area and track for which the recording output level is to be obtained are instructed, a seek operation is performed, and the target track is accessed (step S1). Since it is necessary to erase already written data before performing the trial writing operation, a data track erasing operation is instructed (step S2). However, in the case of a DOW (Diret Over Write) type medium, it is possible to directly write without an erasing operation, so an erasing operation is not necessary.
[0040]
Next, in order to determine the waveform of the recording output level to be emitted, signal generation conditions as shown in FIG. 5 are provided in each block of the write pulse generation unit 12, the amplitude modulation signal generation unit 13 and the sawtooth wave generation unit 14. And the generation timing is instructed (step S3). In FIG. 5, the signal output from the write pulse generation circuit 12 is write data corresponding to a pit, which is greatly described in the illustrated relationship, but is actually a high-frequency signal.
Thereafter, trial writing on a predetermined track, that is, formation of a test pattern is instructed and executed (step S4). Next, the reproduction operation is started, and the reproduction signal from the track test pattern is read into the envelope detection circuit 7 (step S5).
[0041]
Then, the envelope detection circuit 7 finds a temporal position at which the envelope characteristic is minimum from the read data (step S6), and then obtains a recording output level when writing from this temporal position (step S7). . When calculating the output level for recording, if the averaging process is necessary for the purpose of absorbing the variation in the measured value, it is necessary to repeat the process from step S2 to step S7 several times. (Step S8), and the recording output level based on the average value is determined (step S9).
[0042]
Further, it is determined whether or not it is necessary to set a recording output level in another medium area (step S10). If the same processing is necessary (YES), after seeking to the designated track (another track), Returning to step S2, the same processing is repeated, the optimum recording output level in the instructed medium area is obtained, and the process proceeds to the subsequent conventional recording operation (not shown).
[0043]
As described above, according to the present embodiment, it is a recording output level that can sufficiently secure the reproduction signal amplitude in a state where the cross erase / cross write characteristic value is kept below a level that satisfies the desired error rate. Therefore, data can be written to adjacent recording tracks without damaging already recorded data and with sufficient C / N secured.
[0044]
In addition, as a method of trial writing on the recording medium surface with continuously different recording output levels, the recording output is modulated each time by modulating the recording output with a signal in which a positive wave is superimposed on a sawtooth wave. The process of measuring the reproduction signal amplitude by changing the output level can be performed in a single process, and as a result, the optimum recording output level can be obtained in a short time.
[0045]
Further, by obtaining a so-called differential gain characteristic in the recording output level versus the read signal amplitude characteristic, it is possible to make the slope of the increasing function noticeable, so that the configuration is simple and short. In a state where the cross erase / cross write characteristic value is kept small in the time processing time, it is possible to set a recording output level that can sufficiently secure the reproduction signal amplitude.
[0046]
Data erasure is basically the same as the recording timing and calculation method described in this embodiment, and no pits are generated for the purpose of erasing by continuously emitting laser light or reducing cross erase. A method of erasing with a high-frequency pulse of about the degree can be applied, and the cross erase can be further reduced.
[0047]
【The invention's effect】
As described above in detail, according to the present invention, the cross-erase / cross-write characteristic value can be reduced by measuring and processing in a short time by utilizing the recording / reproducing characteristic peculiar to the land / groove recording method suitable for high-density recording. It is possible to provide a magneto-optical disk drive apparatus that accurately obtains a recording output level capable of sufficiently ensuring a reproduction signal amplitude in a maintained state.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration example of an embodiment of a magneto-optical disk drive device according to the present invention.
FIG. 2 (a) is a diagram showing the characteristics of a recording output level of a light spot, FIG. 2 (b) is a diagram showing a read signal amplitude, and FIG. It is a figure which shows signal envelope.
FIG. 3 is a flowchart for explaining an operation of a pickup mechanism section of the magneto-optical disk drive device according to the present embodiment.
FIG. 4 is a diagram showing a relationship between a recording output level and a reproduced read signal amplitude value in a land / groove recording system suitable for a high-density recording system used in the magneto-optical disk drive device of the present invention.
FIG. 5 is a timing chart showing the generation timing of each signal input to the LD driver.
FIG. 6A is a diagram illustrating an actual detailed signal waveform of a light spot, and FIG. 6B is a diagram illustrating an example of an information track on which a test pattern is recorded.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Optical pick-up part 2 ... Servo PD output signal 3 ... Focus / tracking / feed servo circuit 4 ... Arithmetic processing and control circuit 5 ... RF signal detection PD output signal 6 ... RF head amplifier 7 ... Envelope detection circuit 8 ... Forward PD output signal for monitoring 9 ... forward monitor I / V circuit 10 ... LD driver 11 ... target value signal 12 ... write pulse generator 13 ... amplitude modulation signal generator 14 ... sawtooth wave generator

Claims (1)

A focus error detection optical system and a focus servo means for focusing the light spot on the recording surface of the magneto-optical disk;
In a magneto-optical disk drive device that has a tracking error detection optical system and tracking servo means for following a light spot on an information track in a magneto-optical disk, and records the land and groove of the magneto-optical disk
Amplitude modulation means for amplitude-modulating the recording output of the light spot with a signal in which a sine wave is superimposed on a sawtooth wave ;
A level variation means for the recording output of the modulated light spot is varied continuously level,
Recording means for recording an arbitrary test pattern on a specified target track on the surface of the recording medium with the recording output level fluctuating;
Detecting means for detecting an amplitude envelope of a reproduction signal obtained by reproducing a test pattern on the recording medium surface;
A recording output level detecting means for detecting a minimum value in an amplitude envelope value of the reproduction signal and detecting a recording output level written in a test pattern recorded by the recording means from a detection time position of the minimum value;
A recording output in which the detection means detects the target track a plurality of times, calculates an average value of the plurality of recording output levels obtained, and sets the average value as a recording output level Level setting means;
Magneto-optical disk drive apparatus according to claim ingredients Bei to Rukoto a.

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