JP2001184652A - Information recording/reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent plural times of quantum efficiency of a light emitting element obtained before optimum recording power is decided from being dispersed. SOLUTION: Whether or not OPC is to be performed is judged in a step 1, and when to be performed is judged, a test area to test write is gained in the step 2, and a kind of an optical disk and reference power at a one-fold speed write-in time is read, and the reference power: Pref at the OPC time is calculated, and the power sufficiently higher than the reference power: Pref is calculated, and light emission for obtaining the quantum efficiency in a focal state based on the calculated power is performed and the quantum efficiency is obtained, and ACC light is emitted by using the quantum efficiency, and the OPC is performed, and the optimum recording power of the optical disk is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a write-once type (Wri
The present invention relates to an information recording / reproducing apparatus that records information by performing calibration of a recording laser power on a recording medium such as a te-once disk or a rewritable disk.

[0002]

2. Description of the Related Art An information recording / reproducing apparatus such as an optical disc apparatus uses a laser diode (hereinafter abbreviated as "LD") as a light source as a light source, and automatically emits light from the LD when recording and reproducing information. Light emission power control (Auto
(Omatic Power Control: APC)
Is controlled to have a constant power.

In the case of a general writable optical disk, first, a light to be emitted from the LD and APC is performed in a state where the optical disk is not present or in an out-of-focus state even when the optical disk is present, so that a current to be passed through the LD, that is, a quantum Efficiency (= LD emission power / LD drive current) is determined.

Here, as common sense when designing an optical disc,
It is known that the quantum efficiency differs between when there is return light due to reflection from the optical disk to the LD and when there is no return light. In other words, the state where there is no optical disk, or the state where the optical disk is out of focus even with the optical disk (that is, the state where there is no return light)
When the writing is started with the quantum efficiency determined or adjusted in the above, the difference between the set amount of light and the actual light emission power is caused by a large difference in the amount of return light, and the recording quality on the optical disc is deteriorated.

Conventionally, as a solution to the above-described problem, the actual light writing is started with a current slightly reduced from the current to be supplied to the LD obtained by performing light emission without return light, thereby starting the write operation. The difference between the set power at the time and the actual emission power is reduced, and
A method of controlling the set power and the actual light emission power to be equal after the start of the actual writing (for example,
29126) has been proposed.

Here, a write-once optical disc (Compac)
In t Disc Recorder (CD-R), in order to determine the recording power at the time of writing, an optimum recording power determination method by test writing before recording (Optimum Power).
r Control (OPC).

[0007] OPC is simply test writing. CD-R discs have 10
Zero test areas (partitions) are provided. Each partition, that is, one OPC is determined to be 15 frames (= 1/75 sec at 1 × speed).

As a method for obtaining the optimum recording power, one frame is allocated to one write power (LD emission power), recording is performed from a minimum to a maximum with a power of 15 steps, and then that portion is reproduced. The voltage of the peak: P and the bottom: B of the envelope of the RF signal that is the reproduction signal is detected.

Then, the laser power at which the value of β = (P + B) / (P−B) becomes a preset value (about 0.04 as a recommended value) is determined as the optimum recording power of the optical disk. I try to keep a record.

As described above, in the case of a CD-R, the recording time of one frame written with one write power is short. For example, at 1 × speed, it is only 1/75 second, and at 2 × speed, it becomes そ の, and at 4 × speed, it becomes 1/4, which becomes even shorter as the write speed increases. Therefore, even if OPC is performed by performing power control in the above-described manner, one frame ends before the emission power becomes equal to the set power.

If the set power is different from the actual LD light emission power, the actually written recording power is not known, so that an accurate optimum recording power cannot be obtained. The quality of the reproduced signal in the portion that has been deteriorated.

Therefore, in order to solve such a problem,
After writing to find the quantum efficiency at the time of focusing using a part of the test area, and then performing test writing to find the optimum recording power, the difference in the quantum efficiency between focused and unfocused can be obtained. It is possible to obtain a correct optimum recording power without depending, and to improve the write quality.

Here, a description will be given of the write power that changes when performing OPC. Orange Book Part 2 Version 3.0, which is a CD-R standard (Orange
According to Book Part II version 3.0), the variable range of the write power: Pw can be expressed by the following equation 1 when the reference value is Pref.

[0014]

## EQU1 ## Pref × 0.7 <Pw <Pref × 1.3

The reference value: Pref can be expressed by the following equation (2).

[0016]

Pref = Pind × [1 + 0.4 × (N−1)]

In the equation (2), Pind is information recorded in advance on an unrecorded optical disk, reference power at 1 × speed writing: N is a writing speed, and N at 4 × speed.
= 4.

Further, as a specific example of numerical values obtained by the above equations (1) and (2), the information written on the optical disk is Pin = 5.9 mW. 13 mW.

Therefore, Pref × 0.7 = 9.1 m
W and Pref × 1.3 = 16.9 mW, and can be varied with the write power of 15 steps within the range shown in the above equation 1, so that the 15 write powers are as follows.

9.1 mW, 9.7 mW, 10.2 m
W, 10.8 mW, 11.3 mW, 11.9 mW, 1
2.4mW, 13.0mW, 13.6mW, 14.1m
W, 14.7 mW, 15.2 mW, 15.8 mW, 1
6.3mW, 16.9mW

At each of these powers, one frame is written in order, that is, at 4 × speed, so that a total of 15 frames are written in 1/75/4 seconds, and are reproduced to obtain an optimum recording power which is the best write power. Perform the write.

[0022]

However, in the above-described method, since it is desired to calculate the quantum efficiency by writing close to the actual writing power, the quantum efficiency at the time of focusing using the power near the Pref is required. However, since the write power to be written when calculating the quantum efficiency at the time of focusing before OPC is not particularly taken into consideration, Pre
In the vicinity of f (Pin at 1 × speed), the reflectance greatly changes due to a slight change in the writing power.

Therefore, as described above, the quantum efficiency is affected by the return light (the reflectance and the amount of return light are proportional), so that the quantum efficiency greatly changes due to a slight difference in the degree of application. .

This means that if writing for obtaining the quantum efficiency is performed a plurality of times, the data will vary every time, and it was naturally required to perform OPC by ACC light emission using such varied quantum efficiency. There is also a problem that the optimum recording power varies and the recording quality deteriorates.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and has as its object to prevent the quantum efficiency of the light emitting element obtained a plurality of times before determining the optimum recording power from varying.

[0026]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention seeks the quantum efficiency of light emitted from a light emitting element when information is recorded on a recordable recording medium. On the basis of this, the optimum recording power is determined by performing test writing on a test writing area provided in advance for determining the optimum recording power on the recording medium, and information is recorded on the recording medium by the optimum recording power, and the recorded information is recorded. In the information recording / reproducing apparatus provided with means for reproducing, the light emission power of the light emitting element when the quantum efficiency is obtained is determined by the type of the recording medium and the information recording speed. A means for setting the value to a value sufficiently higher than the above is provided.

Further, the quantum efficiency of the irradiation light of the light emitting element when information is recorded on the recordable recording medium is obtained, and the recording medium is provided in advance for determining the optimum recording power on the recording medium based on the obtained quantum efficiency. In an information recording / reproducing apparatus having means for recording information on the recording medium and reproducing the recorded information with the optimal recording power by performing test writing on the trial write area, It is preferable to provide a means for setting the light emission power of the light emitting element at the time of obtaining the efficiency to a value sufficiently lower than a reference value uniquely determined by the type of the recording medium and the information recording speed.

Further, the quantum efficiency of the irradiation light of the light emitting element when information is recorded on the recordable recording medium is determined, and the recording medium is provided in advance for determining the optimum recording power on the recording medium based on the determined quantum efficiency. In an information recording / reproducing apparatus having means for recording information on the recording medium and reproducing the recorded information with the optimum recording power by performing test writing on the trial writing area, The light emission power at the time of light emission of the element is set to a sufficiently lower value and a sufficiently higher value than a reference value uniquely determined by the type of the recording medium and the information recording speed, and the quantum efficiency is obtained. It is preferable to provide a means for obtaining a quantum efficiency near the reference value based on the two quantum efficiencies and performing the test writing based on the quantum efficiency.

[0029]

Embodiments of the present invention will be specifically described below with reference to the drawings. First, an optical disc of a recording medium embodying the present invention, an information recording / reproducing apparatus for recording and reproducing information on and from the optical disc, and a defect related to a normal determination of a recording power in the information recording / reproducing apparatus will be described.

As a recordable high-density disc, a write-once (Writable) type of recording and reproduction using a laser beam is used.
e Once) and a rewritable type. Both optical discs have different recording surface materials for recording information signals,
The method of recording information is also different.

A write-once optical disk has a recording surface formed by using a material such as Te or Bi, and a pit is formed by irradiating the recording surface with a laser beam to melt the portion.
There are two methods: a method of forming a thin film of 2Se3, TeOx or an organic dye, and applying a laser beam to the recording surface thereof to change the light reflectance.

On the other hand, in the case of a rewritable optical disk, the material of the recording surface is a rare earth metal (Ga, Tb, Dr, Ho, etc.).
And a 3d transition metal (Fe, Co, Ni) is used, and a magneto-optical recording method (Magnet Optics) is used for signal recording.

In recording on such a rewritable optical disk of a material, a predetermined portion of a recording surface previously initialized by an external magnetic field is heated to a Curie temperature (about 150 ° C.) by irradiating a laser beam, and the external magnetic field is applied thereto. And perpendicularly magnetized.

The reading of information recorded on the recording surface is performed by using the Kerr effect phenomenon in which the polarization plane rotates very slightly when light is applied to the recording surface.

Incidentally, a pre-groove is formed on the recording surface of the CD-R disc which is the write-once type optical disc described above. The pregroove has a center frequency of 2
The wobbling is extremely slight in the radial direction at 2.05 kHz. Then, by using the wobble signal detected from the wobbling, it is possible to control the optical disk before recording information at a constant linear velocity.

The wobble signal has a maximum deviation of ± 1.
Since a signal multiplexed by FSK modulation at kHZ is included, ATIP (absolute time) can be determined by reading this signal, so that it is possible to search for an arbitrary position even before recording information.

FIG. 7 shows the format of a CD-R disc. The recording surface of the CD-R disc is arranged in the power calibration area (P
CA) 1, a program memory area (PMA) 2, a lead-in area 3, a program area 4, and a lead-out area 5.

PCA1 is an area for recording / measuring the optimum recording power of the disk before recording, and PMA2 is an area for temporarily recording recording information and skip information when a disk being additionally recorded is taken out.

In the information recording / reproducing apparatus, such a CD-
In order to determine the optimum recording power for recording on the R disk, a recording power calibration (OPC) operation is usually performed before recording.

Therefore, a CD-R disc contains 100
A test area (partition) for each test is provided. Each partition is 15 frames.

The determination of the optimum recording power at the time of recording as described above requires the optimum recording power for each disk because the recording characteristics of the optical disk differ from manufacturer to manufacturer. If the optimum recording power cannot be obtained for each optical disc, the error rate and jitter after recording, that is, the reproduction quality may suddenly deteriorate.

FIG. 8 is a diagram for explaining a process for obtaining the optimum recording power. For example, as shown in (a) of the figure, one frame is allocated to one recording level (laser power), recording is performed from the minimum value A to the maximum value B with a power of 15 steps, and then that portion is reproduced. And RF
The voltage of the peak: P and the bottom: B of the signal envelope is detected.

Next, as shown in FIG.
A recording power is obtained from a laser power or a linear approximation in which the value of (P + B) / (P−B) becomes a preset value (recommended value is about 0.04), and the recording power is determined as the optimum recording power of the optical disk. The subsequent recording is performed.

FIG. 9 shows an automatic light emission power control (Automatic Power Controller) of the information recording / reproducing apparatus.
ol: APC) is a diagram illustrating an example of a configuration of a circuit. A front PD (or rear PD) 10 in the figure is a light receiving element for monitoring laser power for performing APC.
An element that converts laser light into current by photoelectric conversion.

The I / V amplifier 11 converts the current output from the front PD (or the rear PD) 10 into a voltage and outputs it. The output is a laser emission waveform as shown in FIG. 10 and a square wave of a binary voltage of a read power level voltage: C and a write power level voltage: D. Must be sampled and held.

The first sample and hold circuit shown in FIG.
/ H circuit) 12 holds the output of the front PD (or rear PD) 10 at the time of read power, and the second sample / hold circuit (second S / H circuit) 13 holds the output of the front PD at the time of write power.
The output of D (or rear PD) 10 is held.

Laser driver (Laser Drive)
r) 20 is a laser diode (Laser Diode)
e: LD) 21 to drive a current proportional to the input voltage to the LD 21. Also, a function is provided for superimposing the current at the time of write power on the read power when the EFM signal is high (High: H).

Then, each output is converted into a digital value by the first A / D converter 14 and the second A / D converter 15 and sent to the CPU 16, and information indicating the relationship between each output and the light emission power is obtained in the manufacturing process or the like. Then, it is stored in the nonvolatile memory 17.

Then, the CPU 16 of the information recording / reproducing apparatus
Is a laser diode (L) such that the output is at the time of the emission power set based on the information in the nonvolatile memory 17.
Adjust the current flowing in D).

That is, the digital set value from the CPU 16 is transferred to the first D / A converter 18 and the second D / A converter 1.
The laser driver 20 converts the analog value into an analog value at 9 and supplies a current proportional to the voltage to the LD 21 so that the LD 2
1 emits light, and A
Perform PC.

As described above, the CPU 16 controls the current flowing to the LD 21 so that the output of the monitor becomes a desired value, thereby automatically controlling the recording power.

In the information recording / reproducing apparatus having the above-described APC circuit, usually, the focus servo is deliberately shifted prior to the start of writing to perform APC for read power emission and write power emission in an out-of-focus state, and then perform a setup operation. Are doing.

That is, the pickup is moved to the TOC area of the optical disk, the focus servo is turned on, and the spindle kick, the spindle CAV servo, and the tracking servo are turned on.

After the end of the setup operation, it is determined whether or not to execute OPC. In determining whether or not to perform the OPC, if the OPC has been performed after the currently set optical disk is powered on, the OPC is not performed.

Here, when executing OPC, PCA
The head of the count area is searched, then the PCA count area is reproduced, and the count value is determined from the address of the RF signal. After the determination of the count value is completed, the PCA test area corresponding to the count value is searched.

Thereafter, the OPC operation is performed. That is, P
After the test writing is performed in the CA test area, the test writing result is reproduced, and the optimum recording power (power of β value = 0.04) is determined based on the reproduction result. here,
The β value is a parameter indicating the recording power obtained by the reproduced signal after recording.

As described above, in general, the APC is performed without intentionally focusing on the optical disk by intentionally shifting the focus servo. However, if the laser drive current value obtained by APC when the laser light emission power is out of focus is driven as it is after focusing, there is a problem that the light is emitted with a stronger power than the unfocused emission power. is there.

In other words, when focus servo is performed to return light to the laser diode, the light emission power differs from the set power at the current value set without the optical disk.

FIG. 11 is a diagram showing an example of the relationship between the laser diode drive current and the light emission power. In the information recording / reproducing apparatus described above, actual writing is started with a current slightly reduced from the current to be supplied to the LD obtained by performing light emission without return light, and the difference between the set power at the start of writing and the actual light emission power is obtained. Will be described below, and power control is performed so that the set power and the actual light emission power become equal after the actual writing starts.

In the case of a CD-R disc, at the time of OPC, one frame to be written at one recording level has a short time. For example, it is only 1/75 second at 1 × speed, and furthermore, the writing speed is 2 × and 4 × speed. When the power increases, the power becomes shorter than 1/2 times and 1/4 of that at the time of 1 × speed. The frame ends. That is, when high-speed recording is performed, AP
C control is not in time.

The fact that the APC control cannot be performed in time means that the set power and the actual LD emission power are different. Since the actually written recording power is not known, an accurate optimum recording power cannot be obtained. A problem arises in that the reproduced signal quality of a portion recorded with an incorrect optimum power is degraded.

Therefore, in order to solve the above-mentioned problems, in the information recording / reproducing apparatus, the quantum efficiency is obtained in advance at the time of focusing in which the APC is performed in a part of the test writing area, and the quantum efficiency is used. A case will be described in which light emission during ACC is set to ACC.

FIG. 12 is a diagram showing a specific sequence of the test writing process in the information recording / reproducing apparatus, and FIG. 13 is a diagram showing the writing power of the optical disk written in the process of the sequence shown in FIG. .

As shown in FIG. 12, in this OPC process, it is determined in step (indicated by "S" in the figure) 31 whether or not OPC is to be executed. A test area to be written is obtained, and the process proceeds to step 33 to obtain a quantum efficiency by light emission in the PCA test area.
Information indicating that the OPC area has been used once is recorded in the count area.

Proceeding to step 35, the PCA count area is again counted in the PCA count area to obtain a test area for test writing, and proceeding to step 36, OPC is executed using the quantum efficiency obtained immediately before OPC in step 33, and the optimum The recording power is determined and determined, and the process proceeds to step S37, where information indicating that the OPC area has been used once is recorded in the PCA count area, and this processing ends.

Further, FIG. 13 shows the OP in the above processing.
The recording power around the center value that varies at the time of C is shown.

In the above-described processing, since the recording power for obtaining the in-focus quantum efficiency is not taken into consideration, the following problems are caused. This will be described below.

FIG. 14 is a diagram showing the relationship between the write power (the output power from the LD) and the amount of light returning to the LD due to reflection on the optical disk. When writing to the optical disk does not occur at all, the recording film does not melt. When the recording power is increased, the reflectivity of the optical disk is constant. Therefore, simply as indicated by the straight line L1 (dashed line in the figure), The amount of return light also monotonically increases.

However, in the case of a write-once (WO) disk such as a CD-R, the recording film melts out near the optimum recording power, so that as shown by a straight line L2 (solid line in the figure),
The return light amount of D greatly changes near the optimum recording power: Pref.

FIG. 15 is a diagram for explaining the cause of a change in the amount of return light described in the Orange Book, which is a CD-R standard. (A) of the figure shows the waveform of the emitted light emitted from the LD,
FIG. 3B is a diagram showing a waveform of the reflected light from the optical disk.

Here, when the light emission power (write power) from the LD is small, the reflected light has the same shape as the emitted light as it is, but since the head of the pulse cannot be written on the optical disk with the power at which the recording film melts, the reflected light is not emitted. However, the reflected light decreases as the optical disk melts and the reflectivity decreases as it goes toward the trailing edge of the pulse.

The trailing edge power of the reflected light gradually decreases as the emission power increases, because the melting is large and the reflectance is greatly reduced. However, since the melting of the recording film is completed with a certain power, when the power becomes higher than that power, the light returns monotonously again and the light increases.

Due to the above phenomenon, an inflection point is formed near the optimum recording power: Pref as shown in FIG. Here, the quantum efficiency differs depending on whether or not return light (due to reflection from the optical disk) is present in the LD.

On the other hand, when writing to an optical disc,
Even if the power emitted from the optical disk is constant, it is inevitable that the power itself applied to the optical disk surface fluctuates minutely due to a slight warp or a difference in thickness of the optical disk.

Therefore, when APC writing is performed in the vicinity of the power where the change of the return light is large, the quantum efficiency changes every moment. In other words, if APC writing for obtaining the quantum efficiency is performed a plurality of times, a different quantum efficiency will be required every time. If ACC writing is performed at the time of OPC using the different quantum efficiency, which is different every time, there arises a problem that the OPC result varies every time.

On the other hand, in the OPC, the power is increased by the power per inflection point near the optimum recording power: Pref shown in FIG. 14, so that the central value of the OPC-variable power (Pref in FIG. Calculating the quantum efficiency with power) causes the above-described problem.

Then, by adopting the function relating to the present invention in the above-mentioned information recording / reproducing apparatus, the ACC
Is performed, the same result as in the case where OPC is performed by APC is obtained, and the variation in OPC is suppressed.

Next, the function and processing when the means according to claim 1 of the present invention is applied to the information recording / reproducing apparatus will be described. In this case, the APC circuit shown in FIG. 3 obtains the quantum efficiency of irradiation light of the light emitting element when information is recorded on a recordable recording medium, and optimizes the recording medium based on the obtained quantum efficiency. Means for performing test writing in a test writing area provided in advance for determining recording power to determine an optimum recording power, recording information on the recording medium with the optimum recording power, and reproducing the recorded information; The light emitting element functions as a means for setting the light emission power of the light emitting element at the time of obtaining quantum efficiency to a value sufficiently higher than a reference value uniquely determined by the type of the recording medium and the information recording speed.

FIG. 1 is a flowchart showing the OPC process according to the first aspect of the present invention in the information recording / reproducing apparatus. In this OPC routine, it is first determined whether or not to execute OPC in step (indicated by "S" in the figure) 1, and if it is determined that OPC is to be executed, the processing of steps 2 to 6 is executed. In step 2, the information in the PCA count area is read and counted, and how many times OPC has already been performed is obtained, and a test area for trial writing is obtained.

Next, in step 3, the disk information embedded in the optical disk is read, and the type of the optical disk and the reference power at the time of 1 × speed writing are read (this corresponds to the Pind in the Orange Book of the CD-R standard). Equivalent to).

From the reference power and the writing speed, the OPC
Reference power at time: Pref (Power centered on OPC)
(In the case of a CD-R, Orange Book Pref = Pind × (1+ (N−1) × 0.
4) is used).

In step 4, if conventional, step 3
The quantum efficiency is obtained by performing light emission with the reference power: Pref determined in (1), but the function according to claim 1 of the present invention calculates a power sufficiently higher than the reference power: Pref. For example, a power that is increased by 30% (or more) of the reference power: Pref is calculated, and light emission for obtaining quantum efficiency in a focused state is performed based on the calculated power.

In step 5, ACC light emission is performed using the quantum efficiency obtained immediately before to perform OPC. First, the reference power: P
It is calculated from ref.

For example, in the case of a CD-R, the information Pind = 5.9 mW written on the optical disk, and in the case of quadruple-speed writing, Pref = 13 mW. Therefore, Pref
× 0.7 = 9.1 mW and Pref × 1.3 = 16.9 m
Since the write power varies in 15 steps within the range of W, the 15 write powers are as follows.

9.1 mW, 9.7 mW, 10.2 m
W, 10.8 mW, 11.3 mW, 11.9 mW, 1
2.4mW, 13.0mW, 13.6mW, 14.1m
W, 14.7 mW, 15.2 mW, 15.8 mW, 1
6.3mW, 16.9mW

The test writing is performed with each power. In the case of the constant current driving, the current to be supplied to the LD is calculated from the quantum efficiency calculated in step 4 and the power to emit light. Write to.

The written portion is reproduced to detect the peak: P and bottom: B voltages of the envelope of the RF signal that is the reproduction signal, and to use each value to obtain β = (P +
The laser power at which the value of (B) / (P−B) becomes a preset value (about 0.04 as a recommended value) is determined as the optimum recording power of the optical disc.

Then, the process proceeds to step S6, where the fact that the OPC area has been used for one time is recorded in the PCA count area, and the OPC process is completed.

FIG. 2 is a diagram showing specific power values written on the optical disk by the OPC process shown in FIG. The area shown in FIG. 7 is an area written by APC for calculating the quantum efficiency, the area is an area written by ACC using the power determined from the obtained quantum efficiency, and the area shown in FIG. This is the recording power that has been written.

As described above, the AP for calculating the quantum efficiency
At the time of writing C, by writing with a high write power with a small change in reflectivity, even if a small change in power occurs, the change in the amount of return light is small because the change in the reflectivity is small, and the calculation of the quantum efficiency of the LD performed a plurality of times varies. OP
The power emitted by the ACC at the time of C does not vary, so that the optimum recording power determined by the OPC does not vary, and as a result, it is possible to provide a system in which the variation in the writing quality is small.

Next, the function and processing when the means according to claim 2 of the present invention is applied to the information recording / reproducing apparatus will be described. In this case, the APC circuit shown in FIG. 3 obtains the quantum efficiency of irradiation light of the light emitting element when information is recorded on a recordable recording medium, and optimizes the recording medium based on the obtained quantum efficiency. Means for performing test writing in a test writing area provided in advance for determining recording power to determine an optimum recording power, recording information on the recording medium with the optimum recording power, and reproducing the recorded information; The light emitting element has a function of setting the emission power of the light emitting element at the time of obtaining the quantum efficiency to a value sufficiently lower than a reference value uniquely determined by the type of the recording medium and the information recording speed.

FIG. 3 is a flowchart showing the OPC process according to the second aspect of the present invention in the information recording / reproducing apparatus. In this OPC routine, it is first determined in step (indicated by "S" in the figure) 11 whether or not to execute OPC, and if it is determined to be performed, steps 12 to 1 are performed.
6 is executed. In step 12, the information in the PCA count area is read and counted.
Is executed, and a test area for trial writing is obtained.

Next, in step 13, the disc information embedded in the optical disc is read, and the type of the optical disc and the reference power at the time of 1 × speed writing are read (this is Pind in the Orange Book of the CD-R standard).
Equivalent).

The OPC based on the reference power and the writing speed
Reference power at time: Pref (Power centered on OPC)
(In the case of a CD-R, Orange Book Pref = Pind × (1+ (N−1) × 0.
4) is used).

In step 14, according to the function of the second aspect of the present invention, a power sufficiently lower than the reference power: Pref is calculated. For example, a power reduced by 30% (or more) of the reference power: Pref is calculated, and light emission for obtaining quantum efficiency in a focused state is performed based on the calculated power.

In step 15, ACC light emission is performed using the quantum efficiency obtained immediately before to perform OPC. First, the reference power is the multiple types of power to test-write in the test area:
It is calculated from Pref.

Then, the test writing is performed at each power. In the case of the constant current driving, the current to be supplied to the LD is calculated from the quantum efficiency calculated in step 14 and the power to emit light, and actual light emission is performed. Write to the test area.

The written portion is reproduced to detect the peak: P and bottom: B voltages of the envelope of the RF signal as the reproduction signal, and to use each value to obtain β = (P +
The laser power at which the value of (B) / (P−B) becomes a preset value (about 0.04 as a recommended value) is determined as the optimum recording power of the optical disc.

Then, the process proceeds to a step 16, wherein the fact that the OPC area has been used for one time is recorded in the PCA count area.
This OPC process ends.

FIG. 4 is a diagram showing specific power values written on an optical disk by the OPC process shown in FIG. The area shown in FIG. 7 is an area written by APC for calculating the quantum efficiency, the area is an area written by ACC using the power determined from the obtained quantum efficiency, and the area shown in FIG. This is the recording power that has been written.

As described above, the AP for calculating the quantum efficiency
By writing at a low write power with a small change in reflectivity at the time of writing C, the change in the amount of returned light is small because the change in the reflectivity is small even if a small change in power occurs, and the calculation of the quantum efficiency of the LD performed a plurality of times varies. Since the power is stable without being applied, the power emitted by the ACC during the OPC does not vary, so that the optimum recording power determined by the OPC does not vary, and as a result, it is possible to provide a system in which the variation in writing quality is small.

Next, the function and processing when the means according to claim 3 of the present invention is applied to the information recording / reproducing apparatus will be described. In the function according to claim 1 or 2, the variation of the quantum efficiency due to the degree of application of the optical disk can be suppressed, but there is a difference between the reference recording power quantum efficiency and the quantum efficiency required before OPC. , Drive the LD ACC from the calculated quantum efficiency
The case where PC is performed and the case where OPC is performed by driving the LD by APC (although this should be done originally, in high-speed writing, the light emission time of one light emission power at the time of OPC is short, and APC cannot be performed in time, so There is a possibility that the power determined in the above (necessary) may deviate.

Therefore, the function according to claim 3 of the present invention prevents the recording power determined by OPC from being determined where it is not the original optimum power, and realizes a further improvement in write quality.

In this case, the APC circuit shown in FIG. 3 determines the quantum efficiency of the light emitted from the light emitting element when information is recorded on the recordable recording medium, and based on the determined quantum efficiency, Means for performing test writing in a test writing area provided in advance for determining an optimum recording power on a medium to determine an optimum recording power, recording information on the recording medium with the optimum recording power, and reproducing the recorded information And setting the light emission power of the light emitting element at the time of light emission to a value sufficiently lower and a value sufficiently higher than a reference value uniquely determined by the type of the recording medium and the recording speed of information, thereby obtaining a quantum efficiency. Based on the two quantum efficiencies thus obtained, a function of means for obtaining a quantum efficiency near the reference value and performing the test writing based on the quantum efficiency is obtained.

FIG. 5 is a flowchart showing an OPC process according to the third aspect of the present invention in the information recording / reproducing apparatus. In this OPC routine, first, in step (indicated by “S” in the figure) 21, it is determined whether or not OPC should be performed.
7 is executed. In step 22, the information in the PCA count area is read and counted, and
Is executed, and a test area for trial writing is obtained.

Next, in step 23, the disc information embedded in the optical disc is read, and the type of the optical disc and the reference power at the time of 1 × speed writing are read (this is referred to as Pind in the Orange Book of the CD-R standard).
Equivalent).

From the reference power and the writing speed, the OPC
Reference power at time: Pref (Power centered on OPC)
(In the case of a CD-R, Orange Book Pref = Pind × (1+ (N−1) × 0.
4) is used).

In step 24, the quantum efficiency is determined by light emission with the reference power: Pref determined in step 23 in the related art. However, according to the function of claim 3 of the present invention, the power is sufficiently lower than the reference power: Pref. And a sufficiently high power is calculated, and light emission for obtaining quantum efficiency is performed in the focused state based on each power.

For example, when a power that is 30% (or more) of the reference power: Pref is calculated, light emission for obtaining quantum efficiency in a focused state is performed based on the calculated power.

Then, the quantum efficiency η1 when the light emission is performed at a power sufficiently lower than the reference power Pref and the quantum efficiency η2 when the light emission is performed at a power higher than the reference power Pref are determined.

In step 25, the quantum efficiency η near the reference power: Pref is obtained by calculation based on the quantum efficiencies η1 and η2. The simplest example is
Is determined by a process based on the operation formula shown in FIG.

[0112]

Η = (η1 + η2) / 2

However, since the temperature of the LD is actually different depending on the light emission power, the efficiency of the LD also depends on the temperature of the LD.
In the case of c, a more realistic value is obtained by processing based on the following equation (4). Note that a, b, and c differ depending on the device type.

[0114]

Η = a × η1 + b × η2 + c

In step 26, OPC is performed by emitting ACC light using the quantum efficiency obtained in the previous step 25. First, a plurality of powers for test writing in the test area are calculated from the reference power: Pref.

Then, the test writing is performed at each power. In the case of the constant current driving, the current to be supplied to the LD is calculated from the quantum efficiency calculated in step 24 and the power to emit light, and actual light emission is performed. Write to the test area.

The written portion is reproduced to detect the peak: P and bottom: B voltages of the envelope of the RF signal that is the reproduced signal, and to use the values to obtain β = (P +
The laser power at which the value of (B) / (P−B) becomes a preset value (about 0.04 as a recommended value) is determined as the optimum recording power of the optical disc.

Then, the process proceeds to a step 27, wherein the fact that the OPC area has been used once is recorded in the PCA count area.
This OPC process ends.

FIG. 6 is a diagram showing specific power values written on the optical disk by the OPC processing shown in FIG. The area shown in FIG. 7 is an area written by APC for calculating the quantum efficiency, the area is an area written by ACC using the power determined from the obtained quantum efficiency, and the area shown in FIG. This is the recording power that has been written.

As described above, in addition to the effects of the functions according to the first and second aspects of the present invention, the type and apparatus of the optical disk determine the quantum efficiency obtained at a high power and the quantum efficiency obtained at a low power. By calculating the quantum efficiency in the vicinity of the recording power serving as the reference to be estimated by estimation, and performing ACC light emission at the time of OPC based on the calculated quantum efficiency, the optimum recording power substantially equal to the case of performing the APC at the time of OPC is determined. It is possible to do
Write quality to optical disc is OPC A
The recording quality level can be set to the level of PC emission.

[0121]

As described above, according to the information recording / reproducing apparatus of the present invention, the quantum efficiency of the light emitting element which is obtained a plurality of times before determining the optimum recording power does not vary. The optimum recording power can be determined correctly, and the recording quality can be improved.

[Brief description of the drawings]

FIG. 1 is a flowchart showing an OPC process according to claim 1 of the present invention in an information recording / reproducing apparatus embodying the present invention.

FIG. 2 is a diagram showing specific power values written on an optical disc by the OPC process shown in FIG. 1;

FIG. 3 is a flowchart showing OPC processing according to claim 2 of the present invention in the information recording / reproducing apparatus embodying the present invention;

FIG. 4 is a diagram showing specific power values written on an optical disc by the OPC process shown in FIG. 4;

FIG. 5 is a flowchart showing an OPC process according to claim 3 of the present invention in the information recording / reproducing apparatus embodying the present invention.

FIG. 6 is a diagram showing specific power values written on an optical disc by the OPC process shown in FIG. 5;

FIG. 7 is a diagram showing a format of a CD-R disc.

FIG. 8 is a diagram for describing a process for obtaining an optimum recording power.

FIG. 9 is a diagram showing an example of a configuration of an automatic light emission power control (APC) circuit of the information recording / reproducing apparatus embodying the present invention.

10 is a waveform chart showing an example of laser emission power in the APC circuit shown in FIG.

11 is a diagram showing an example of a relationship between a laser diode drive current and a light emission power in the APC circuit shown in FIG.

FIG. 12 is a diagram showing a specific sequence of a trial writing process in the information recording / reproducing apparatus embodying the present invention.

FIG. 13 is a diagram showing the writing power of the optical disk written in the processing of the sequence shown in FIG.

FIG. 14 shows L due to write power and reflection from an optical disk.
FIG. 4 is a diagram illustrating a relationship between light returning to D;

FIG. 15 is a diagram for explaining the cause of a change in the amount of return light described in the Orange Book, which is a CD-R standard.

[Explanation of symbols]

 1: Power calibration area (PCA) 2: Program memory area (PMA) 3: Lead-in area 4: Program area 5: Lead-out area 10: Front PD (or rear PD) 11: I / V amplifier 12: First Sample hold (first S / H) circuit 13: second sample hold (second S / H) circuit 14: first A / D converter 15: second A / D converter 16: CPU 17: nonvolatile memory 18: first D / A Converter 19: 2nd D / A converter 20: Laser driver 21: Laser diode

Claims (3)

[Claims] 1. A quantum efficiency of irradiation light of a light emitting element when information is recorded on a recordable recording medium is determined, and the recording medium is provided in advance on the recording medium for determining an optimum recording power based on the determined quantum efficiency. An information recording / reproducing apparatus having means for recording information on the recording medium and reproducing the recorded information with the optimal recording power by performing test writing on the trial write area. A means is provided for setting the light emission power of the light emitting element at the time of obtaining the efficiency to a value sufficiently higher than a reference value uniquely determined by the type of the recording medium and the information recording speed. Information recording and reproducing apparatus. 2. A method for determining a quantum efficiency of light emitted from a light emitting element when information is recorded on a recordable recording medium, and based on the determined quantum efficiency, provided in advance in the recording medium for determining an optimum recording power. An information recording / reproducing apparatus having means for recording information on the recording medium and reproducing the recorded information with the optimal recording power by performing test writing on the trial write area. Means are provided for setting the light emission power of the light emitting element at the time of light emission when obtaining efficiency to a value sufficiently lower than a reference value uniquely determined by the type of the recording medium and the recording speed of information. Information recording and reproducing apparatus. 3. A quantum efficiency of irradiation light of a light emitting element when information is recorded on a recordable recording medium, and the recording medium is provided in advance for determining an optimum recording power on the recording medium based on the determined quantum efficiency. An information recording / reproducing apparatus having means for recording information on the recording medium and reproducing the recorded information with the optimal recording power by performing test writing on the test writing area. The light emission power at the time of light emission of the element is set to a sufficiently lower value and a sufficiently higher value than a reference value uniquely determined by the type of the recording medium and the information recording speed, and the quantum efficiency is obtained, respectively. An information recording / reproducing apparatus, further comprising: means for obtaining a quantum efficiency near the reference value based on the two quantum efficiencies and performing the test writing based on the quantum efficiency.