JP3089844B2 - Write-once optical disk recording device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art For example, a write-once 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. I have. In this write-once optical disc, basically, a test write area (PCA; Power Control Area) is provided on the innermost peripheral side.
a) is formed, and a data write area is formed outside the area a).

When writing data to such a write-once optical disc, test writing is performed in the test writing area so that the asymmetry of the reproduction signal is constant, and the resulting laser beam with which the asymmetry is constant is obtained. The light output is set to the optimum output, and data is written to the data write area while maintaining the optimum output.

[0004]

However, in the above-mentioned conventional write-once optical disc recording apparatus, an optimum output of the laser output is obtained in the test writing area, and the data is written in the data writing area by the optimum output. Even, the laser output which is optimal due to the temperature change of the light emission output of the laser element and the unevenness of sensitivity in the plane of the write-once optical disc, the laser output that is optimally changed due to warpage, etc., changes in the data writing area, and after all, is constant, in other words, There has been a problem that writing cannot be performed while maintaining optimal asymmetry.

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

[0006]

According to the present invention, for example, FIG.
As shown in FIG. 5, a laser drive means 7 for controlling the intensity of a writing light beam to a target value LP1 in order to form a pit on a write-once optical disc 5, and a reflected light intensity during formation of a pit by the writing light beam To pit level P1
And a second detecting means for detecting, as the land level L1, the reflected light intensity of the reading light beam applied to the land after the formation of the pits.
Sample-and-hold means 19, read output level forming means 14 for detecting the intensity of the reading light beam and outputting the detected intensity as a read output level, laser driving means 7, first and second sample-and-hold means 18 , 1
9 and a control unit 2 connected to the read output level forming unit 14. When writing data to the write-once optical disc 5, the control unit 2 firstly has a certain asymmetry in the test writing area 5a. Target value LP1, pit level P1, and land level L
1 and the read output level R1 are respectively set to the initial value LP.
i, Pi, Li, and Ri. Then, when data is written in the data writing area 5b, the current target value LP1, pit level P1, and land level L
1 and the read output level R1 are respectively set to the current value LP.
n, Pn, Ln, Rn, and initial values LPi,
Pi, Li, Ri and current values LPn, Pn, Ln, R
Based on n, control is performed so as to newly determine the current value LPn of the target value.

[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 when a constant asymmetry is obtained in the test writing area 5a. And the land level L1 and the read output level R1 are stored as initial values LPi, Pi, Li, and Ri, respectively. Next, when data is written in the data write area 5b,
The current target value LP1, pit level P1, land level L1, and read output level R1 are taken as current values LPn, Pn, Ln, and Rn, respectively, and the initial value L
Pi, Pi, Li, Ri and current values LPn, Pn, L
Based on n and Rn, control is performed so that the current value LPn of the target value is newly determined. Therefore, optimal recording of data on the write-once optical disc 5 can be continuously performed stably for a long time.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the write-once optical disc 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 Right)
Various EFM data signals D1 are supplied to the CPU 2 as control means from an input section 1 of a Fourteen Modulation (Fourteen Modulation) data signal. The data signal that is the basis of the EFM data signal D1 supplied to the input unit 1 is
The data is supplied from a host computer (not shown), and is converted into an EFM data signal D1 at the input unit 1.

The EFM data signal D1 output from the input unit 1 is a fixed EFM data signal D for test writing.
There is an EFM data signal Dv such as t and image data.

In order to form a pit on the write-once optical disc 5 during the high level period of the EFM data signal D1, the CPU 2 sets the current write output target value (hereinafter referred to as the target value) LPn of the write level to D. APC (Automatic) on the writing side through the / A conversion circuit 6
In addition to the supply 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 of the write-once optical disc 5 is assigned as a test writing area 5a, and the outer circumference is assigned as a data writing area 5.

[0014] switch 9, the switching control signals S1, write-once optical disc 5 during a write operation for forming pits on the (EFM period of the data signal D ₁ of the high level), the movable contact 9a is a write-side APC circuit The switch is switched to the fixed contact 9b connected to the switch 7. On the other hand, the formed pits and and low-level period of the EFM data signal D ₁ during the readout operation of the land, is switched to the fixed contact 9c side movable contact 9a is connected to the APC circuit 10 out side reading .

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 reading 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 enters the optical system 15. The optical system 15 includes 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. After the light beam is converted into parallel light through the collimator lens, the light beam is condensed through the beam splitter and the objective lens, and the converged light beam is applied to the write-once optical disc 5.

Here, a part of the light beam applied to the write-once optical disc 5 is output by the front monitor 14 as a front monitor output. The front monitor output is an output proportional to the intensity of the writing light beam and the intensity of the reading light beam. The APC circuit 7 supplies the front monitor output proportional to the intensity of the writing light beam to the comparison input. In this way, 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 read light beam intensity is taken into the CPU 2 as a read output level R1.

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

The sample and hold circuits 18 and 19 receive the sample and hold pulse SP from the clock generation circuit 22.
1, SP2 are supplied. The clock generation circuit 22
A predetermined clock signal is supplied to the input unit 1 of the EFM data signal and the CPU 2 from the CPU.

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, respectively, are output from the A / D conversion circuit 2.
The signals are supplied to the CPU 2 as the pit level P1 and the land level L1 through the CPUs 3 and 24.

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

First, a trial write area 5 of the write-once optical disc
The fixed EFM data signal Dt for test writing is supplied from the EFM data signal input unit 1 to the CPU 2 from the input unit 1 of the EFM data signal in order to obtain a constant asymmetry at which the intensity of the light beam for writing is optimized using a.

The CPU 2 has a fixed EF for trial writing.
After taking in the M data signal Dt, a predetermined laser output target value LP1 is supplied to the D / A conversion circuit 6 in accordance with the M data signal Dt. 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 test writing area 5a of the write-once optical disc 5. And a pit having a predetermined length corresponding to the EFM data signal Dt is formed, and a portion where the pit is not formed becomes a land.

In this case, the fixed EFM for trial writing
The pits and lands formed based on the data signal Dt are 3T pits to 11T pits and 3T lands, respectively.
11T lands, and the number of pits and lands is the same. Therefore, the data is read out by the reading light beam,
The asymmetry of the reproduction signal So obtained at the output side of is constant. For example, when the constant value is a zero value, the center level of the amplitude value of the reproduction signal So matches the zero level of the direct current. In other words, when the amplitude of the reproduction signal So becomes equal to the amplitude above and below the zero level, it can be said that the asymmetry is the zero value. This asymmetry can be determined by observing the reproduced signal So with an oscilloscope.

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

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

Therefore, by changing the laser output target value LP1 by the CPU 2 while observing the tube waveform of the oscilloscope, it is possible to determine the laser output target value LP1 at which a constant asymmetry can be obtained in the test writing area 5a. it can. Note that the configuration can be changed so that the laser output target value LP1 at which a certain asymmetry is obtained is automatically obtained. It has been experimentally determined by the inventors that the constant asymmetry value is experimentally set to a value between -4% and -7% from the zero value so as to minimize data errors and the like. Has been confirmed.

Therefore, in the test writing area 5a, the CPU 2 sets the constant asymmetry value, in other words, the laser output target value LP1 when the optimum asymmetry value is obtained, as the initial laser output target value LPi (optimum value).
(Step S11 in the flowchart).

Next, the initial value LPi of the write laser output target value thus determined and the read laser output value at that time, that is, the front monitor 1
A / D conversion circuit 16 as front monitor output from
The read output level R1 supplied to the CPU 2 from is stored in the CPU 2 as an 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 used as the A / D conversion circuit 2
3 through the CPU 2 as the initial value Pi of the pit level.
(Step S12).

Further, 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 sampled and held value is A / D
The converted value is stored in the CPU 2 as the land level initial value Li via the conversion circuit 24 (step S12).

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

In FIG. 5, the interval between the 0T pit position and the 11T pit position is a write light beam output period TW.
The other section is an output period TR of the reading light beam. The reason that the reflected light intensity has a peak value immediately after the 0T pit position is that the write-once optical disk 5 has a mirror surface, and the reflected light intensity decreases due to the continuous irradiation of the light beam.

In this embodiment, the pit level is 4T
The pit level P1 at the pit position is sampled and held by the sample and hold circuit 18. It has been confirmed by the inventors and others that the pit level P1 can be detected stably by sampling and holding the pit level P1 at the 4T pit position. As the land level, the land level L1 at the time when the reflected light intensity is stabilized is sampled and held. The sample hold position (point in time) is determined by the sample hold pulse S supplied from the clock generation circuit 22.
Since it can be changed by controlling the point in time when P1 and SP2 occur, not only the 4T pit position but also 3T
The pit position or the 5T pit position can be appropriately changed.

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 each taken in about 75 times a minute, and Are the pit level initial value Pi, the land level initial value Li, and the read output level initial value Ri as CP.
It is stored in U2.

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

Next, a process of sequentially writing data optimally, that is, so as to have the above-mentioned constant asymmetry, from the inner peripheral side to the outer peripheral side of the data write area 5b of the write-once optical disc 5, a so-called running OPC ( Op
(time power control) operation will be described.

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

Therefore, when writing data to 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 and hold circuits 18 and 19 as the current pit level value Pn, the current land level Ln and the current read output level Rn, respectively. After holding, CPU2
(Step S13).

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

[0043]

## EQU1 ## Current value of the normalized pit level Pnorm = Current value of the pit level Pn / (Target ratio of laser output × Reflectance ratio)

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

[0045]

## EQU2 ## Laser output target value ratio = current value of laser output target value / initial value of laser output target value = LPn / LPi

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

[0047]

## EQU3 ## Reflectance ratio = Current value of reflectance / Initial value of reflectance =
(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, Equation 1 is represented by the character formula shown in Equation 4.

[0049]

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

Next, the current value Pnorm of the normalized pit level obtained for the first track of the data write area 5b and the test write area 5a are determined as the optimum values for obtaining a certain asymmetry. The magnitude of the set pit level is compared with the initial value Pi (step S15).

If they have the same value, it is assumed that the first track has been optimally written with a certain 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 remaining, the current value Pn of the laser output target value is changed to the current value Pn. Without changing, steps S13 to S1 are performed again.
The processing up to 8 is performed.

In the determination of step S15, Pnor
When m> Pi, the reflected light intensity is larger than the optimum reflected light intensity, and therefore the current value L of the laser output target value is obtained.
Pn is increased by one unit (for example, when the full scale is 256 levels, for example, 1/256 level) so that the reflected light intensity is reduced (step S1).
6).

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

In this manner, 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. Write area 5b
Can be written uniformly 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 the current value LP of the laser output target value in the above equation (2).
By solving for n, the following equation 5 can be obtained.

[0056]

## EQU5 ## LPn = (Pn / Pnorm) × (Li / R
i) × (Rn / Ln) × Lpi = (Pn / Pi) × (L
i / Ri) × (Rn / Ln) × Lpi

As described above, according to the above-described embodiment, the CP
When data is written 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 are set when the test writing area 5a is set to have a constant asymmetry. Of the laser output target value, the current value Pn of the laser output target value, the current value Pn of the pit level, and the land value of the land level when writing data to the data write area 5b. The current value Ln and the current value Rn of the read output level are fetched, and the new laser output target value Pn is determined so as to satisfy Expression 5. For this reason, from the start of writing to the test writing area 5a to the end of writing to the entire surface of the write-once optical disc 5, the temperature change of the laser diode, which varies every moment, and the warpage and sensitivity of the write-once optical disc 5 The emission output intensity of the laser beam can be changed in accordance with a change factor such as unevenness, so that optimum recording of data on the write-once optical disc 5 can be continuously performed stably for a long time.

In the above embodiment, the read output level R1 is controlled while taking into consideration. However, if the read output level R1 does not change, R
Since n = Ri, there is no need to consider the read output level R1.

Further, it goes without saying that the present invention is not limited to the above-described embodiment, but can adopt various configurations 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, in the test writing area, the target value, pit level and land level, and read output level of the light beam for writing when a certain asymmetry is obtained. Each is stored as an initial value, and then, when data is written in the data write area, the current target value, the pit level and land level, and the read output level are respectively taken as current values, and the initial value and Based on the current value, control is performed so as to newly determine the current value of the target value.
Therefore, optimal recording of data on the write-once optical disc can be performed continuously and stably for a long time.

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

[Brief description of the 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 illustrating a write-once optical disc.

FIG. 3 is a flowchart for explaining the operation of the example in FIG. 1;

FIG. 4 is a diagram used for explaining asymmetry.

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

[Explanation of symbols]

 Reference Signs List 1 EFM data signal input section 5 Write-once optical disc 7, 10 APC circuit 8 Laser diode circuit 14 Front monitor 15 Optical system 18, 19 Sample hold circuit

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-61-239441 (JP, A) JP-A-2-292726 (JP, A) JP-A-60-83234 (JP, A) JP-A-3-3 250427 (JP, A) JP-A-61-16042 (JP, A) JP-A-6-44565 (JP, A) JP-A-3-78126 (JP, A) JP-A-6-44564 (JP, A) JP-A-4-10237 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G11B ^7/ 00-7/005 G11B 7/125 JOIS

Claims (3)

(57) [Claims] 1. A laser driving means for controlling the intensity of a writing light beam to a target value in order to form a pit on a write-once optical disc; First sample-and-hold means for detecting as a land level, second sample-and-hold means for detecting, as a land level, the reflected light intensity of the readout light beam applied to the land after the formation of the pits, and A read output level forming means for detecting the intensity and outputting the read output level 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 writing data on the write-once optical disc, the control means The target value, the pit level and the land level, and the read output level when a certain asymmetry is obtained are stored as initial values, respectively. The target value, the pit level and the land level, and the read output level are respectively taken as current values,
A write-once optical disc device that controls so as to newly determine a 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: initial value of 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 apparatus according to claim 1, wherein the value is determined as: (current value of read output level / current value of land level). 3. The write-once optical disc device according to claim 1, wherein the current value and the initial value of the pit level are a current value and an initial value of a 4T pit position in the EFM data.