JPH0676288A - Draw type optical disk recorder - Google Patents

Abstract

PURPOSE:To stably and properly record in a long time by fetching a target value, etc., at the time of performing so as to become a fixed asymmetry to a test write area and a data write area as an initial value and a present value, and deciding the present value of the target value from them. CONSTITUTION:When data is written in a DRAW type optical disk 5 by a control means 2, first of all, in the test write area 5a, the target values LP1, a pit level P1 and a land level L1, and read output level R1 at the time of performing so as to become the fixed asymmetry are stored as the initial values LPi, Pi, Li, Ri. Then, when the data is written in the data write area 5b, the present target value LP1, the pit level P1 and the land level L1, and the read output level R1 are fetched as the present values LPn, Pn, Ln, Rn. Then, this device is controlled so that the present value LPN of the target value is decided newly based on these initial values and present values.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a write-once type optical disc recording apparatus for writing data on a write-once type optical disc by a light beam.

[0002]

2. Description of the Related Art For example, a write-once type optical disk is known in which an organic recording material is applied to one surface of a disk having the same size as a compact disk (CD) and arbitrary data is written on the one surface by a light beam. There is. In this write-once optical disc, basically, a test writing area (PCA; Power Control Area) is provided on the innermost side.
a) is formed, and a data writing area is formed outside the area.

When writing data on such a write-once type optical disc, a trial writing is performed in the trial writing area so that the asymmetry of the reproduction signal becomes constant, and the resultant asymmetry laser becomes constant. The light output is set to the optimum output, and the data is written in the data writing area while maintaining the optimum output.

[0004]

However, in the above-mentioned conventional write-once type optical disk recording apparatus, even if the optimum output of the laser output is obtained in the trial writing area, the data is written in the data writing area by the optimum output. However, the optimum laser output changes in the data writing area due to the temperature change of the light emission output of the laser element and the unevenness of sensitivity in the surface of the write-once optical disc, warpage, etc. There is a problem that writing cannot be performed while maintaining the optimum asymmetry.

The present invention has been made in view of the above problems, and it is an object of the present invention to provide a write-once type optical disc recording apparatus capable of continuously and optimally recording data on a write-once type optical disc stably for a long time. To aim.

[0006]

The present invention is described in, for example, FIG.
As shown in, the laser driving means 7 for controlling the intensity of the writing light beam to the target value LP1 for forming the pits on the write-once optical disc 5, and the reflected light intensity during the formation of the pits by the writing light beam. To pit level P1
And a second sample and hold means 18 for detecting the reflected light intensity of the reading light beam irradiated on the land after the formation of the pit as the land level L1.
Sample hold means 19, a read output level forming means 14 for detecting the intensity of the reading light beam and outputting it as a read output level, a laser drive means 7, first and second sample hold means 18. , 1
9 and the control means 2 connected to the read output level forming means 14. When writing data to the write-once optical disc 5, the control means 2 first makes a constant asymmetry in the trial writing area 5a. Target value LP1, pit level P1 and land level L
1 and read output level R1 to the initial value LP
i, Pi, Li, Ri, and then, when writing data in the data writing area 5b, the present target value LP1, pit level P1, and land level L
1 and the read output level R1 are the current values LP.
Captured as n, Pn, Ln, and Rn, initial values LPi,
Pi, Li, Ri and current values LPn, Pn, Ln, R
Based on n, the current value LPn of the target value is controlled to be newly determined.

[0007]

According to the present invention, when data is written to the write-once optical disc 5 by the control means 2, first, the target value LP1 and the pit level P1 are set when the test writing area 5a has a certain asymmetry. The land level L1 and the read output level R1 are stored as initial values LPi, Pi, Li, Ri, respectively, and then, when data is written in the data writing area 5b,
The current target value LP1, pit level P1 and land level L1, and read output level R1 are taken in as current values LPn, Pn, Ln, and Rn, respectively, and the initial value L
Pi, Pi, Li, Ri and current values LPn, Pn, L
The current value LPn of the target value is controlled to be newly determined based on n and Rn. Therefore, optimum recording of data on the write-once type optical disc 5 can be continuously and stably performed for a long time.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the write-once type optical disk recording apparatus of the present invention will be described below with reference to the drawings.

FIG. 1 shows the configuration of one embodiment.

In FIG. 1, EFM (Eight to
The various EFM data signals D1 are supplied from the input unit 1 of the Fourteen Modulation) data signal to the CPU 2 as the control means. The data signal which is the basis of the EFM data signal D1 supplied to the input unit 1 is
It is supplied from a host computer (not shown), and is converted into an EFM data signal D1 at the input section 1.

As the EFM data signal D1 output from the input section 1, a fixed EFM data signal D for trial writing is used.
There are EFM data signals Dv such as t and image data.

Since the CPU 2 forms pits on the write-once optical disc 5 during the high level period of the EFM data signal D1, the current laser output target value LPn at the writing level (hereinafter referred to as the target value current value) LPn is D. The APC (Automatic) on the writing side through the A / A conversion circuit 6.
In addition to being supplied to the reference input side of the power control circuit 7, the switching control signal S1 of the switch 9 is supplied to the control terminal of the switch 9 arranged on the input side of the laser diode circuit 8 in synchronization with this.

FIG. 2 shows the basic structure of the recording surface of the write-once optical disc 5. As shown in FIG. 2, the inner circumference side of the write-once optical disc 5 is allocated as a trial writing area 5a, and the outer circumference side thereof is allocated as a data writing area 5.

In the writing operation for forming pits on the write-once type optical disc 5 by the switching control signal S1 (the high level period of the EFM data signal D ₁ ), the switch 9 has the movable contact 9a on the writing side of the APC circuit. It is switched to the fixed contact 9b side connected to the 7 side. On the other hand, during the read operation of the formed pits and lands and during the low level period of the EFM data signal D ₁ , the movable contact 9a is switched to the fixed contact 9c side connected to the read side APC circuit 10. .

A constant DC voltage E1 is supplied from a DC power supply 11 to the reference input side of the APC circuit 10 on the read side.

The output signal of the switch 9 is converted by the laser diode circuit 8 into a light beam having an intensity corresponding to the output signal, and the light beam is incident on the optical system 15. The optical system 15 has a front monitor 14 having a photodiode (not shown), a collimator lens (not shown), a beam splitter, an objective lens, a cylindrical lens, a focus actuator, a tracking actuator, and the like, and is incident from the laser diode circuit 8. After the light beam is collimated by the collimator lens, it is condensed through the beam splitter and the objective lens, and the condensed light beam is applied to the write-once optical disc 5.

Here, a part of the light beam with which the write-once type optical disc 5 is irradiated is output by the front monitor 14 as a front monitor output. This front monitor output is an output proportional to the intensity of the writing light beam and the intensity of the reading light beam, and the APC circuit 7 is supplied to the comparison input with the front monitor output proportional to the intensity of the writing light beam. The writing light beam AP
C control is performed. Further, the APC circuit 10 performs APC control of the reading light beam by supplying a front monitor output proportional to the reading light beam intensity to the comparison input.

The front monitor output is converted into a digital data signal by the A / D conversion circuit 16, and the front monitor output proportional to the reading light beam intensity is taken into the CPU 2 as the read output level R1.

The reflected light beam from the write-once type optical disc 5 is incident on the photodetection circuit 17 having, for example, a four-division photodiode through the optical system 15. The output signal of the photodetector circuit 17 is supplied to the sample-hold circuit 18 for detecting the pit level and the sample-hold circuit 19 for detecting the land level, and also to the reproducing circuit 20. Further, well-known focus servo and tracking servo are performed based on the output signal of the photodetector circuit 17. The output signal So of the reproducing circuit 20 is supplied to a waveform observing device, for example, an oscilloscope through an output terminal 21.

The sample and hold circuits 18 and 19 are connected to the sample and hold pulse SP from the clock generation circuit 22.
1, SP2 are supplied. In addition, the clock generation circuit 22
Supplies a predetermined clock signal to the EFM data signal input unit 1 and the CPU 2.

The pit level and the land level (the contents of which will be described later), which are the output signals of the sample and hold circuits 18 and 19, are respectively the A / D conversion circuit 2
It is supplied to the CPU 2 as the pit level P1 and the land level L1 through 3, 24.

Next, the operation of the above embodiment will be described with reference to the flowchart shown in FIG.

First, the trial writing area 5 of the write-once type optical disk
Using a, a fixed EFM data signal Dt for trial writing is supplied from the EFM data signal input unit 1 to the CPU 2 in order to obtain a constant asymmetry in which the intensity of the writing light beam is optimum.

The CPU 2 uses the fixed EF for trial writing.
After fetching the M data signal Dt, a laser output target value LP1 predetermined in accordance therewith is supplied to the D / A conversion circuit 6. In this case, through the D / A conversion circuit 6, the APC circuit 7, the switch 9 and the laser diode circuit 8, a light beam having an intensity corresponding to the laser output target value LP1 is transmitted from the optical system 15 to the trial writing area 5a of the write-once optical disc 5. And pits of a predetermined length corresponding to the EFM data signal Dt are formed, and the portions where no pits are formed become lands.

In this case, a fixed EFM for trial writing is used.
The pits and lands formed based on the data signal Dt are 3T pits to 11T pits and 3T lands, respectively.
It is an 11T land, and the number of pits and lands is the same. Therefore, it is read by the reading light beam, and the reproducing circuit 20 is read through the photodetector circuit 17.
The asymmetry of the reproduction signal So obtained at the output side of the is a constant value. For example, when the constant value is zero, the center level of the amplitude value of the reproduction signal So coincides with the DC zero level. In other words, it can be said that the asymmetry has a zero value when the amplitude of the reproduction signal So has the same amplitude above and below the zero level. This asymmetry can be found by observing the reproduction signal So with an oscilloscope.

FIG. 4 schematically shows the waveform of the reproduction signal So observed by an oscilloscope. From the values of the amplitude A and the amplitude B above and below the zero level, the asymmetry can be calculated by the following equation.

Asymmetry = (1/2) · {(B-A)
/ (B + A)} × 100 [%]

Therefore, by varying the laser output target value LP1 by the CPU 2 while observing the screen waveform of the oscilloscope, it is possible to determine the laser output target value LP1 at which a constant asymmetry is obtained in the trial writing area 5a. it can. The laser output target value LP1 with which a certain asymmetry is obtained can be changed in configuration so as to be automatically obtained. Further, as a constant asymmetry value, it has been experimentally found by the inventors that a value between -4% and -7% rather than a zero value is an asymmetry value that minimizes data errors. It has been confirmed.

Therefore, in the trial writing area 5a, the laser output target value LP1 when the constant asymmetry value, in other words, the optimum asymmetry value is obtained, is set as the initial value LPi (optimum value) of the laser output target value to the CPU2.
(Step S11 in the flowchart).

Next, the initial value LPi of the writing laser output target value thus determined and the reading laser output value at that time, that is, the front monitor 1
As the front monitor output from the A / D conversion circuit 16
The read output level R1 supplied from the CPU 2 to the CPU 2 is stored in the CPU 2 as the initial value Ri of the read output level (step S12).

Further, the writing laser output target value LP
While the pit is formed by i, the reflected light intensity at the 4T pit position is sampled and held by the sample and hold circuit 18 based on the sample and hold pulse SP1, and the sampled and held value is the A / D conversion circuit 2
CPU3 as the initial value Pi of the pit level via 3
(Step S12).

Furthermore, when the initial value Ri of the read output level is stored, the reflected light intensity of the reading light beam applied to the land is sampled and held by the sample and hold circuit 19 based on the sample and hold pulse SP2, The sample-held value is A / D
The initial value Li of the land level is stored in the CPU 2 via the conversion circuit 24 (step S12).

FIG. 5 shows sample hold circuits 18 and 19
2 schematically shows the waveform of the above-described reflected light intensity supplied to the.

In FIG. 5, the period from the 0T pit position to the 11T pit position is the output period TW of the writing light beam,
The other section is the output period TR of the reading light beam. The reflected light intensity reaches the peak value immediately after the 0T pit position because the write-once optical disc 5 has a mirror surface, and the continuous irradiation of the light beam reduces the reflected light intensity.

In this embodiment, the pit level is 4T.
The pit level P1 at the pit position is sample-held by the sample-hold circuit 18. The inventors have confirmed that the pit level P1 at the 4T pit position can be stably detected by sample-holding. As for the land level, the land level L1 when the reflected light intensity becomes stable is sampled and held. The sample hold position (time point) is the sample hold pulse S supplied from the clock generation circuit 22.
Since it can be changed by controlling the time points of occurrence of P1 and SP2, it is not limited to the 4T pit position and 3T
The pit position or the 5T pit position can be changed appropriately.

In this embodiment, in step S12, the initial value Pi of the pit level, the initial value Li of the land level and the initial value Ri of the read output level are taken in about 75 times per minute, respectively. Of the pit level as the initial value Pi, the land level as the initial value Li, and the read output level as the initial value Ri.
It is stored in U2.

In this way, as a result of steps S11 and S12, a certain asymmetry can be obtained in the CPU 2 by performing the trial writing in the trial writing area 5a, that is, the laser output target value at which the optimum writing is performed. The initial value LPi, the average pit level initial value Pi, the land level initial value Li, and the read output level initial value Ri are stored.

Next, the process of writing data in order from the inner circumference side to the outer circumference side of the data writing area 5b of the write-once optical disc 5 in an optimum manner, that is, the above-mentioned constant asymmetry, so-called running OPC ( Op
The operation of the time power control will be described.

The running OPC operation described below may be performed for each track or a plurality of tracks.

Therefore, when writing data on the first track, the initial value LPi of the laser output target value obtained as described above is referred to as the current laser output target value (hereinafter referred to as the current value of the laser output target value). ) It is supplied from the CPU 2 to the D / A conversion circuit 6 as LPn.

The pit level P1, the land level L1 and the read output level R1 at that time are sampled by the sample hold circuits 18 and 19 as the current value Pn of the pit level, the current value Ln of the land level and the current value Rn of the read output level, respectively. After holding, CPU2
Is stored in the memory (step S13).

Next, the current value of the pit level (hereinafter referred to as the current value of the normalized pit level) Pnorm normalized based on the equation 1 is obtained (step S14).

[0043]

[Formula 1] Current value of normalized pit level Pnorm = Current value of pit level Pn / (laser output target value ratio × reflectance ratio)

In Expression 1, the laser output target value ratio is defined as in Expression 2.

[0045]

## EQU00002 ## Laser output target value ratio = current value of laser output target value / initial value of laser output target value = LPn / LPi

In Expression 1, the reflectance ratio is defined as in Expression 3.

[0047]

## EQU00003 ## Reflectance ratio = current reflectance value / initial reflectance value =
(Current value of land level / Current value of read output level)
/ (Initial value of land level / initial value of read output level) = (Ln / Rn) / (Li / Ri)

Therefore, the expression 1 is represented by the character expression shown in the expression 4.

[0049]

(4) Pnorm = Pn / [(LPn / LPi) ×
{(Ln / Rn) / (Li / Ri)}]

Next, by using the current value Pnorm of the normalized pit level obtained for the first track of the data writing area 5b in this manner and the trial writing area 5a as an optimum value for obtaining a certain asymmetry, The size of the pit level is compared with the initial value Pi (step S15).

If they have the same value, it is assumed that the first track is optimally written with a constant asymmetry. In that case, it is next determined whether or not the writing operation to all the tracks has been completed (step S18). If there are still unwritten tracks, the current value Pn of the laser output target value is set. Without any change, the steps S13 to S1 are performed again.
Perform processing up to 8.

In the determination of step S15, Pnor
In the case of m> Pi, the reflected light intensity is larger than the optimum reflected light intensity. Therefore, the present value L of the laser output target value is L.
Pn is increased by one unit (for example, 1/256 level when the full scale is at 256 level) to reduce the reflected light intensity (step S1).
6).

Further, in the determination of step S15, P
When norm <Pi, the reflected light intensity is smaller than the optimum reflected light intensity. Therefore, the current value LPn of the laser output target value is decreased by one unit (similarly, 1/256 level), and the reflected light intensity is decreased. The strength is increased (step S17).

In this way, the output intensity of the light beam applied to the next writing area (track) is determined so as to obtain an optimum value, that is, a constant asymmetry, and the data of the write-once optical disc 5 is thus obtained. Writing area 5b
It becomes possible to write evenly over the entire surface.

After all, the light beam output intensity to be determined, in other words, the current value LPn of the laser output target value is determined.
Is the current value LP of the laser output target value in Equation 2 above.
By solving for n, it can be expressed as in the following Expression 5.

[0056]

[Formula 5] LPn = (Pn / Pnorm) × (Li / R
i) × (Rn / Ln) × Lpi = (Pn / Pi) × (L
i / Ri) × (Rn / Ln) × Lpi

Thus, according to the above-mentioned embodiment, the CP
When writing data to the write-once optical disc 5 by U2, first, the initial value LPi of the laser output target value, the initial value Pi of the pit level, and the land level when the asymmetry is set to be constant in the trial writing area 5a The initial value Li and the initial value Ri of the read output level are stored respectively. Next, when writing the data in the data writing area 5b, the current value Pn of the laser output target value, the current value Pn of the pit level, and the current value Pn of the land level are written. The current value Ln and the current value Rn of the read output level are respectively taken in, and the new laser output target value Pn is determined so as to satisfy the expression 5. Therefore, from the start of writing in the trial write area 5a to the end of writing on the entire surface of the write-once optical disc 5, the temperature change of the laser diode changes every moment, and the warp / sensitivity of the write-once optical disc 5 changes. The emission output intensity of the laser light can be changed by following a change factor such as unevenness, and the optimum recording of data on the write-once optical disc 5 can be continuously and stably performed for a long time.

In the above embodiment, the read output level R1 is also taken into consideration for control. However, when the read output level R1 does not change, R in the above equation 5 is used.
Since n = Ri, it is not necessary to consider the read output level R1.

Furthermore, it is needless to say that the present invention is not limited to the above-mentioned embodiments, and various configurations can be adopted without departing from the gist of the present invention.

[0060]

As described above, according to the present invention,
When writing data to the write-once optical disc by the control means, first, the target value of the writing light beam, the pit level and the land level, and the read output level when a certain asymmetry is set in the trial writing area are set. Each of them is stored as an initial value, and next, when writing data in the data writing area, the current target value, the pit level and the land level, and the read output level are respectively taken in as current values, and the initial value and The current value of the target value is controlled to be newly determined based on the current value.
Therefore, the optimum recording of data on the write-once optical disc can be continuously and stably performed for a long time.

Therefore, the written optical disk produced by using the present invention has a high quality with little error.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of a write-once optical disc recording apparatus according to the present invention.

FIG. 2 is a diagram for explaining a write-once optical disc.

FIG. 3 is a flowchart provided for explaining the operation of the example in FIG.

FIG. 4 is a diagram used for explaining asymmetry.

FIG. 5 is a diagram used for explaining a relationship between reflected light intensity of laser light and a pit level and the like.

[Explanation of symbols]

 1 EFM data signal input section 5 write-once type optical disk 7, 10 APC circuit 8 laser diode circuit 14 front monitor 15 optical system 18, 19 sample hold circuit

Claims (3)

[Claims] 1. A laser driving means for controlling the intensity of a writing light beam to a target value for forming a pit on a write-once optical disc, and a reflected light intensity of the reflected light intensity while the pit is formed by the writing light beam. Of the reading light beam, and second sample and hold means for detecting the reflected light intensity of the reading light beam irradiated on the land after the pit formation as the land level. A read output level forming means for detecting the intensity and outputting it as a read output level; and a control means connected to the laser driving means, the first and second sample and hold means, and the read output level forming means. When the data is written to the write-once optical disc, the control means first puts the data in the trial writing area. , The target value, the pit level and the land level, and the read output level when the asymmetry is set to a constant value are respectively stored as initial values, and next, when writing data in the data writing area, Of the target value, the pit level and the land level, and the read output level of
A write-once optical disc device that controls so as to newly determine the current value of the target value based on the initial value and the current value. 2. The current value of the target value in the control means is an initial value of the target value × (current value of pit level / initial value of pit level) ×× (initial value of land level / initial value of read output level) 2. The write-once optical disc device according to claim 1, wherein the write output type optical disc device is determined as: (current value of read output level / current value of land level). 3. The write-once optical disc apparatus according to claim 1, wherein the current value and the initial value of the pit level are the current value and the initial value of the 4T pit position in the EFM data.