JP3754338B2 - Optical head light emission output control method for optical disk recording apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical head light emission output control method for an optical disk recording apparatus that controls the light emission output of an optical head in an optical disk recording apparatus that records a data signal on a disk using a light beam from the optical head, and more particularly to a recording sensitivity on a disk. The present invention relates to an optical head light emission output control method for an optical disk recording apparatus in which the light emission output of the optical head is corrected and recorded in accordance with the variation of the optical head.
[0002]
[Prior art]
CD-R (Recordable) drives and CD-RW (ReWritable) drives of the CD (Compact Disc) family are well known as optical disk recording apparatuses that record digital data signals on a disk using a light beam from an optical head. ing.
[0003]
A disc recorded by such an optical disc recording apparatus has a recording sensitivity difference due to a manufacturer due to a difference in material, a recording sensitivity difference due to an individual difference due to variation, or unevenness within the same disc. Difference in recording sensitivity.
[0004]
By the way, in the optical disc recording apparatus, the light emission output emitted from the optical head at the time of recording is controlled to compensate for the difference in recording sensitivity, and the light emission output of the optical head is set to an optimum recording level optimum for recording on the disc. .
[0005]
The light emission output of the optical head is set by changing the light emission output step by step in a calibration area for light emission output setting provided separately from the program area for recording the actual data signal on the disc at the start of recording. The test signal is written by trial, and the β value (recording depth) is detected by using the peak value and the bottom value of the HF signal reproduced by reading the test signal with the optical head.
[0006]
During the disk recording operation, the reflection level of the recording pulse is detected and controlled to compensate for the light emission output according to the reflection level, and the light emission output in the state where the data signal is actually recorded on the disk is optimally recorded. Matching the level is also done.
[0007]
[Problems to be solved by the invention]
By the way, the control of the light emission output of the optical head during the above-described disk recording operation, so-called running OPC (Optimum Power Control), does not actually detect the recording state of the data signal recorded on the disk. There has been a problem that the light emission output of the set optical head does not match the actual optimum recording level.
[0008]
In addition, in the optical disk recording apparatus, the recording speed is increased. To increase the recording speed, the ZCLV method for changing the linear linear speed (CLV) for each zone of the disk or the constant angular speed (CLV) The data is recorded on the disc at a constant linear velocity by the CAV method in which the disc is rotated at (CAV).
[0009]
In this ZCLV method or CAV method, the recording speed changes depending on the disc diameter, and it is necessary to change the data for setting the light emission output of the optical head according to the recording speed. Therefore, when the ZCLV method or CAV method is adopted, running OPC There was a problem that could not get the data.
[0010]
[Means for Solving the Problems]
According to the first aspect of the present invention, a data signal is output using a light receiving output output from one of the two divided areas of the sub light receiving area for receiving the reflected light obtained from the sub beam located behind the main beam in time. Is read from the disk, and when the disk is recorded, the data signal read by the divided area is sampled during the period when the light emission output of the optical head becomes one of the recording level and the reproduction level. The recording state of the data signal recorded on the disk is detected, and the light emission output of the optical head is controlled according to this detection. As a result, when the light spot corresponding to the main beam is on-track and half of the light spot corresponding to the rear sub-beam is arranged on the adjacent signal track, a high-quality data signal is received from one of the sub-light-receiving areas. I try to get it.
According to the second aspect of the present invention, at the time of recording on the disk, the light output from the optical head is read from the disk by the sub beam temporally behind the main beam during a period when the light emission output of the optical head becomes one of the recording level and the reproduction level. The data signal is sampled, the sampled data signal is selected by a selection circuit, and the reproduced test signal is selected by the selection circuit when reproducing the test signal written on the calibration area of the disk. A data signal and the test signal are selectively supplied to a detection circuit for detecting a recording state, and the detection circuit detects the recording state of the data signal when recording on a disc, and the detection circuit when reproducing the test signal To detect the recording state of the test signal, and in response to this detection, the optical head To control the light output. As a result, the detection circuit is shared between the recording of the data signal on the disk and the reproduction of the calibration area.
[0011]
【Example】
FIG. 1 is a circuit block diagram showing an embodiment of a CD-R drive realizing an optical head light emission output control method of an optical disk recording apparatus according to the present invention.
[0012]
In FIG. 1, reference numeral 1 denotes an optical head that emits a laser beam that traces a signal track of a disk and writes and reads a data signal to and from the disk.
[0013]
The optical head 1 diffracts a laser beam emitted from a laser light source (not shown) by a diffraction grating (not shown), in addition to the 0th-order beam of diffracted light that becomes a main beam for writing a data signal. , The disk is irradiated with a ± first-order beam of diffracted light as a sub-beam, and each beam, as shown in FIG. 2, has a light spot S1 formed by irradiating the main beam correctly placed on the signal track n of the disk. In this state, the light spots S2 and S3 formed by irradiating the sub-beams are adjacent signal tracks on the outer peripheral side and the inner peripheral side on the far side from the light spot S1 in the light spots S2 and S3, respectively. n + 1) and signal track (n-1).
[0014]
The optical head 1 includes a photodetector that receives each reflected light from which the main beam and each sub beam are reflected by a disk. The photodetector includes each of the main beam and each sub beam, as shown in FIG. A main light receiving area A and a pair of sub light receiving areas B and C each receiving reflected light are provided.
[0015]
The main light receiving area A and the pair of sub light receiving areas B and C are each divided into at least two by dividing lines in the direction corresponding to the signal track direction of the disk. Each divided region of the sub light receiving regions B and C generates a light receiving output corresponding to the amount of light received.
[0016]
2 generates a HF signal (high frequency signal) of a data signal recorded on the disk by using a light receiving output generated from a predetermined light receiving region of the photodetector of the optical head 1, and amplifies and binarizes the data signal. A head amplifier for generating a focus error signal between the main beam from the optical head 1 and the signal surface of the disk and a tracking error signal between the main beam from the optical head 1 and the signal track of the disk; Accordingly, the focus control for focusing the main beam on the signal surface of the disk and the tracking control for following the signal track of the disk according to the tracking error signal are performed, and the optical head 1 itself is moved in the radial direction of the disk. This is a head servo circuit that performs thread feeding control.
[0017]
A decoder 4 demodulates the binary data of the HF signal output from the head amplifier 2 in synchronization with the bit clock. The decoder 4 performs EFM demodulation according to EFM (Eight to Fourteen Modulation), which is a modulation code according to the CD standard, from the binarized data of the input HF signal, and demodulates various data according to the data structure.
[0018]
Reference numeral 5 denotes an interface for controlling data transfer with a host device such as a personal computer connected via the connection terminal 6, and 7 encodes input data input via the interface 5 into a data structure recorded on a disk. At the same time, the encoder modulates an EFM signal corresponding to a CD standard modulation code.
[0019]
8 is used to cache the input data input by the interface 5 and is used to modulate the recording data to be recorded on the disk by the encoder 7, caches the data read from the disk, and demodulates the data by the decoder 4. This is a buffer RAM used for processing.
[0020]
A head output control circuit 9 generates a control output for controlling a laser beam generated from the optical head 1 based on the EFM data output from the encoder 7, and 10 corresponds to a control output from the head output control circuit 9. It is a laser drive circuit that drives the laser light source of the optical head 1 to perform recording on a disk.
[0021]
Reference numeral 11 denotes a sample-and-hold circuit that samples and holds an HF signal (details will be described later) obtained by the rear sub-beam, and 12 denotes an HF signal obtained by the sample-and-held HF signal obtained through the sample-and-hold circuit 11 and the main beam. A selection circuit 13 that selectively supplies a signal to the subsequent stage, 13 detects a peak value Vmax and a bottom value Vmin of the HF signal selected by the selection circuit 12, and detects a β value from these values. Circuit. The β value detection circuit 13 controls the head output control circuit 9 based on the detected β value to set the light emission output by the optical head 1 during recording.
[0022]
The sample hold circuit 11 has a sample period and a hold period set according to the EFM recording signal output from the head output control circuit 9.
[0023]
14 is a switch for switching the selection circuit 12 in accordance with the setting of a reproduction mode for reproducing a test signal trial-written in the calibration area of the disc at the start of recording and a recording mode for performing actual recording in the program area of the disc. It is a control circuit.
[0024]
First, generation of a tracking error signal and an HF signal related to the gist of the present invention will be described in detail with reference to FIG. Note that when the astigmatism method is used for focus control, at least the main light receiving area A of the photodetector is divided into four crosses, but the description of the generation of the focus error signal is omitted, and the description is simplified. For this reason, it is shown as in FIG.
[0025]
Each divided region of the main light receiving region A of the photodetector generates light receiving outputs a1 and a2, respectively, each divided region of the sub light receiving region B generates light receiving outputs b1 and b2, and each divided region of the sub light receiving region C. Generate light reception outputs c1 and c2, respectively.
[0026]
The light receiving outputs a1 and a2 generated from the divided areas of the main light receiving area A are obtained by the differential amplifier 21 as the differential outputs of the received light outputs a1 and a2, and are generated from the divided areas of the sub light receiving area B. The respective light reception outputs b1 and b2 are obtained as differential outputs of the light reception outputs b1 and b2 by the differential amplifier 22, and the respective light reception outputs c1 and c2 generated from the respective divided regions of the sub light reception region C are the differential amplifier 23. Thus, a difference output between the light reception outputs c1 and c2 is obtained.
[0027]
The difference output between the light reception outputs b1 and b2 from the differential amplifier 22 and the difference output between the light reception outputs c1 and c2 from the differential amplifier 23 are set so that the output level of one differential amplifier 23 is adjusted by the amplifier 24 in order to match each other's output level. Adjust and then add. The added output obtained by adding the difference output between the light reception outputs b1 and b2 and the difference output between the light reception outputs c1 and c2 is adjusted with the output level by the amplifier 25 and the difference output between the light reception outputs a1 and a2 obtained from the differential amplifier 21. Are then input to the differential amplifier 26.
[0028]
Therefore, the differential amplifier 26 adds the difference output of the light reception outputs b1 and b2 and the difference output of the light reception outputs c1 and c2 adjusted in level by the amplifier 25 and the light reception output a1 obtained from the differential amplifier 21. And a difference output from the difference output of a2. The output signal from the differential amplifier 26 is a tracking error signal (corresponding to a tracking error whose output level and polarity change in accordance with the amount and direction of deviation between the main beam from the optical head 1 and the signal track of the disc, respectively). TE signal).
[0029]
Further, an addition output of the light reception outputs a1 and a2 of each divided area of the main light reception area A is obtained by the addition amplifier 27, and an HF signal of the disk read by the main beam is obtained from the addition amplifier 27. The HF signal is amplified by the HF amplifier 28 and supplied to the subsequent decoder 4.
[0030]
On the other hand, since the signal track adjacent to the inner peripheral side of the disc from the light spot S1 of the main beam is irradiated on the half of the light spot S3 far from the light spot S1, it is generated from one divided region of the sub light receiving region C. The light reception output c1 is an HF signal of the disc that is read by a sub beam that is temporally rearward, and this HF signal is amplified by the HF amplifier 29.
[0031]
By the way, as described above, in the on-track state where the light spot S1 of the main beam is correctly arranged on the signal track n of the disk, the light spot S3 of the rear sub-beam is the half of the disk far from the light spot S1. It is set to be arranged on the adjacent signal track (n-1) on the inner peripheral side. When this setting is performed, the amplitude of the light reception output c1 in one divided region of the sub light receiving region C, that is, the amplitude of the HF signal of the disc read by the rear sub beam is monitored, and the amplitude of the HF signal is maximized. Is set.
[0032]
Note that the light spot S3 shown in FIG. 2 is arranged on the adjacent signal track on the inner peripheral side on the far side from the light spot S1 when the light spot S1 is in an on-track state. Is changed so that the half side near the light spot S1 of the light spot S3 is arranged in the adjacent signal track on the inner peripheral side, and the divided region in the sub light receiving region C corresponding to the half side near the light spot S1 of the light spot S3 The HF signal of the disk may be read by the received light output c2 from the disk. In this case as well, a high quality HF signal having the maximum amplitude can be obtained by the received light output c2.
[0033]
With such an arrangement of the respective light spots shown in FIG. 2, the tracking error signal is about half of the maximum sensitivity of the tracking error signal obtained when the light spots S2 and S3 are arranged in the center between the signal tracks. The amplitude of the HF signal read by the rear sub-beam can be maximized.
[0034]
Next, the recording operation of the disk recording apparatus configured as shown in FIG. 1 will be described.
[0035]
When data requesting recording is transmitted from a host device connected to the connection terminal 6, the data is received by the interface 5 and written in the buffer RAM 8.
[0036]
When the amount of data stored in the buffer RAM 8 reaches the data capacity for starting the encoding process by the encoder 7, the data is read from the buffer RAM 8, and the encoder 7 records an EFM signal to be recorded on the disk in units of EFM frames. Is modulated.
[0037]
The head output control circuit 9 generates an EFM recording signal obtained by converting the EFM signal output from the encoder 7 so that disk recording can be performed at an optimum recording level according to the β value detected by the β value detection circuit 13. This EFM recording signal is composed of a recording level “H” signal for forming a recording mark on the disc and a reproduction level “L” signal for forming no recording mark, and the laser drive circuit 10 optically responds to this EFM recording signal. The laser light source of the head 1 is driven, whereby a recording mark is formed according to the EFM recording signal and recording on the disk is performed.
[0038]
Incidentally, the light emission output emitted from the optical head 1 is set to an optimum recording level optimum for recording on the disk by the head output control circuit 9, and the setting is performed based on the β value detected by the β value detection circuit 13. .
[0039]
The β value detection circuit 13 detects the β value using the HF signal selected by the selection circuit 12 among the HF signal read from the main beam and the HF signal read from the rear sub beam.
[0040]
When the test signal recorded by trial writing to the calibration area of the disc at the start of disc recording is reproduced, the selection circuit 12 is switched to select the HF signal read from the main beam, and the β value detection circuit 13 is selected. Detects the β value using the HF signal.
[0041]
On the other hand, during actual recording in the program area of the disc, the selection circuit 12 is switched to select the HF signal read from the rear sub-beam, and the β value detection circuit 13 detects the β value using the HF signal. .
[0042]
By the way, at the time of actual recording, in order to change the light emission output of the optical head 1 in accordance with the EFM recording signal to be recorded on the disc, the laser light quantity of the rear sub-beam also changes in accordance with the EFM recording signal. Therefore, the HF signal cannot be correctly obtained from the adjacent track on the inner circumference side of the disk simply by extracting the reflected light amount of the rear sub beam from the light receiving area corresponding to the sub beam.
[0043]
In this state, in order to correctly obtain the HF signal from the adjacent track on the inner circumference side of the disc with the rear sub-beam, in the present invention, the light emission output of the optical head 1 at the time of disc recording is a predetermined one of the recording level and the reproduction level. The HF signal read by the sub beam is sampled during the period when the level is reached.
[0044]
In order to sample the HF signal, a sample hold circuit 11 is provided in FIG. The sample hold circuit 11 has a sample period and a hold period set in accordance with the EFM recording signal generated from the head output control circuit 9, samples the HF signal at the recording level of the EFM recording signal, and outputs the HF signal at the reproduction level. Operates to hold.
[0045]
That is, as shown in FIG. 3, the received light output c1 from the divided region in the sub light receiving region C corresponding to the half of the light spot S3 far from the light spot S1, that is, the HF signal read from the rear sub beam is shown in FIG. ) And the EFM recording signal generated from the head output control circuit 9 has the pulse waveform shown in (b) of FIG. 3, the HF signal is converted to (c) of FIG. Converted into the waveform shown. This converted HF signal is a waveform in which the waveform information of the hold period is missing, but since the EFM recording signal and the recording mark of the adjacent track (n-1) are not related, the peak level Vmax of the HF signal is not related. Further, the bottom level Vmin can be detected, and the β value is detected by the β value detection circuit 13 using the HF signal reflecting the EFM recording signal actually recorded on the disc.
[0046]
Therefore, when recording in the program area of the disc, the light output output emitted from the optical head 1 by the head output control circuit 9 according to the β value based on the HF signal read from the EFM recording signal actually recorded one track before. Is set, and the setting is the optimum recording level optimum for recording on the disc.
[0047]
Further, although the light amount of the sub beam is about 1/10 of the light amount of the main beam, for example, the HF signal is sampled at the recording level of the EFM recording signal, so that the rear sub beam in the period during which the sampled HF signal is read. Can be performed at a large level advantageous for signal reading from the disk, and the S / N of the read HF signal becomes good.
[0048]
In the above-described embodiments, the diffracted light is the ± first-order beam as the sub-beam for reading the HF signal. However, the beam quantity is reduced, but it may be the ± second-order beam of the diffracted light. The beam can be arranged with priority given to tracking control, and a high-quality tracking error signal can be obtained.
[0051]
【The invention's effect】
As described above, according to the present invention, data is recorded using a sub beam positioned behind the main beam in a period when the light emission output of the optical head becomes a predetermined level of one of a recording level and a reproducing level. Since the signal is sampled, the recording state of the data signal can be detected correctly, and the light output of the optical head can be set to the optimum recording level that is optimal for recording on the disc. In the optical detector of the head, the sub light receiving area is divided into two in the signal track direction, and in consideration of this, the light spot corresponding to the main beam from one of the sub light receiving areas is rearward in the on-track state. High quality data signals are achieved by placing half of the light spots corresponding to the sub-beams on adjacent signal tracks. Can be obtained, the detection of the recording state is ensured.
[0052]
The present invention also provides a data signal and a test signal supplied from different signal paths between a data signal obtained by sampling a data signal read from a disk and a test signal reproduced after trial writing in the calibration area of the disk. The detection circuit is selected and supplied to a detection circuit that detects the recording state, and the detection circuit can be shared between the calibration area test signal reproduction and the data signal recording on the disk, A rational circuit configuration can be obtained.
[Brief description of the drawings]
FIG. 1 is a circuit block diagram showing an embodiment of a CD-R drive realizing an optical head light emission output control method of an optical disk recording apparatus according to the present invention.
FIG. 2 is a circuit diagram showing details of a part for extracting various signals from each beam of the optical head 1;
FIG. 3 is a waveform diagram for explaining a waveform obtained by the sample hold circuit 11;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Optical head 2 Head amplifier 4 Decoder 7 Encoder 9 Head output control circuit 11 Sample hold circuit 12 Selection circuit 13 β value detection circuit

Claims (2)

Using an optical head that employs a differential push-pull method for tracking control using a main beam that writes data signals to the disk and sub-beams formed before and after the main beam by diffraction, light from this optical head An optical head light emission output control method for an optical disk recording apparatus for controlling light emission output of an optical head in an optical disk recording apparatus for recording a data signal on a disk using a beam, wherein each reflection of a main beam and each sub beam reflected by the disk A signal track in which light is received by the main light receiving region and each sub light receiving region of the photodetector, and the light spot corresponding to the main beam is on-track, and half of the light spot corresponding to the sub beam behind is temporally adjacent. and related disposed, from the rear of the sub-beams The data signal is read from the disk using the light receiving output that is output from one of the two divided areas of the sub light receiving area that receives the reflected light. When the disk is recorded, the light emission output of the optical head is recorded and reproduced. A data signal read by the divided area is sampled during a period when one of the levels reaches a predetermined level, and a recording state of the data signal recorded on the disc is detected using the sampled data signal, and according to this detection An optical head light emission output control method for an optical disk recording apparatus, wherein the light emission output of the optical head is controlled.   An optical head light emission output control method for an optical disk recording apparatus for controlling a light emission output of an optical head in an optical disk recording apparatus for recording a data signal on a disk using a light beam from the optical head, which is emitted from a light source of the optical head A sub beam positioned behind the main beam for diffracting the light beam and writing the data signal is formed on the disc. When recording on the disc, the light output of the optical head is one of the recording level and the reproducing level. When a data signal read from the disk by the sub-beam is sampled during the period of the predetermined level, and the sampled data signal is selected by a selection circuit, and a test signal written on the calibration area of the disk is reproduced. The reproduced test signal is sent to the selection circuit by the selection circuit. The data signal and the test signal are selectively supplied to a detection circuit that detects a recording state, and the recording state of the data signal is detected by the detection circuit during recording on a disc, and the test signal is reproduced. An optical head light emission output control method for an optical disk recording apparatus, wherein the detection state of the test signal is sometimes detected by the detection circuit, and the light emission output of the optical head is controlled according to the detection.

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