JP2005085330A - Tracking control method, focus control method, and optical disk device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tracking control method and a focus control method for performing stable tracking servo and focus servo even if a tracking error signal and a focus error signal possibly vary in amplitude owing to influence of disturbance such as a temperature rise. <P>SOLUTION: The difference between a signal TR+ and a signal TR- is obtained to generate a TE signal. A Peak detecting circuit 11 detects the peak level of the TE signal and a Bottom detecting circuit 12 detects the bottom level of the TE signal; and a TE attenuator 9 adjusts the amplitude of the TE signal so that the difference between the peak level and bottom level has a constant value. An FE signal is also processed similarly and the amplitude of the FE signal is adjusted to generate an FE signal. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical disc apparatus for recording / reproducing information on an optical disc by an optical pickup.

  As optical disc devices, audio CDs, CD-ROMs, CD-R / RWs, DVDs, and the like have already been put into practical use, and application to various fields and development for high performance are being actively conducted. . Particularly recently, with the rapid market expansion of personal computers, the penetration rate of built-in optical disk devices in personal computers has increased.

  In an optical disc apparatus, in order to accurately record or reproduce information, it is necessary that the laser light applied to the optical disc accurately follows the track of the optical disc. This control is performed by generating a tracking error signal and controlling the tracking actuator based on the tracking error signal.

  In addition, it is necessary for the laser light applied to the optical disc to be properly focused on the reflecting surface of the optical disc, and for that purpose, means for controlling the distance between the objective lens that collects the laser light and the optical disc is important. It becomes. This control is performed by generating a focus error signal and controlling the focus actuator based on the focus error signal.

  Here, the focus error signal indicates a shift in the focal direction between the light beam spot emitted from the objective lens provided in the optical pickup and the recording surface of the optical disc. The tracking error signal indicates a deviation in the optical disc radial direction between the light spot and the information track of the optical disc.

  The configuration of the optical disc apparatus will be described with reference to FIG.

  In FIG. 1, an optical disc apparatus irradiates an optical disc 1 with laser light and receives light reflected by the optical disc 1, and converts the reflected light from the optical disc 1 obtained by the optical pickup 2 into a current. , A detector 3 for outputting a signal for reading data from the optical disc 1, an output signal for detecting a focus error, and an output signal for detecting a tracking error, and an output signal output from the detector 3, from which a tracking error signal (hereinafter referred to as an error signal) And a signal calculation unit 4 that generates a focus error signal (hereinafter sometimes abbreviated as “FE signal”).

  The TE signal and the FE signal are input from the signal calculation unit 4 to a digital servo processor (hereinafter abbreviated as “DSP”) 7. The DSP 7 controls the tracking actuator 6 that drives the optical pickup 2 so that the optical pickup 2 follows the track of the optical disc 1 on the basis of the TE signal, and between the objective lens provided in the optical pickup 2 and the optical disc 1. The focus actuator 5 is controlled so that the distance between them is appropriate.

  The above processing of the DSP 7 is executed under the control of the CPU 8.

  A means for generating a tracking error signal and a focus error signal from the output signal output from the detector 3 will be described with reference to FIGS.

  FIG. 10 shows tracking control by the push-pull method, and shows the operation of irradiating the pit 22 formed on the track center 21 of the optical disk with laser light and receiving the reflected light from the pit 22 by the detectors 24 and 25. Thus, half of the spot 23 of the laser light is received by the detector 24 and the other half of the spot 23 is received by the detector 25. The detector 24 obtains a signal TR +, and the detector 25 obtains a signal TR-.

  With respect to TR + and TR− obtained in this manner, a difference is obtained in the circuit shown in FIG. 11A, and the TE signal is generated by setting the amplitude of the TE signal to a predetermined amplitude by the TE attenuator 9.

  Further, the same processing is performed for the focus control. The difference between the FE + and the FE− obtained by the detectors 24 and 25 is determined in the circuit shown in FIG. 11B, and the amplitude of the FE signal is determined by the FE attenuator 10. The FE signal is generated with the amplitude set to.

With respect to tracking servo, Japanese Patent Application Laid-Open No. H10-228707 describes a technique for improving the tracking accuracy by detecting the sensitivity of a servo signal.
JP 9-147373 A

  Tracking servo and focus servo are performed based on the TE signal and FE signal generated by the above method, but the sensitivity of the detector varies due to the influence of disturbance such as a temperature rise, and the reflectance of the optical disk is tracked. The light reception level of the detector varies due to factors such as different positions. If there is such a fluctuation in the received light level, the TE signal and the FE signal vary in amplitude, and a TE amplitude drop and a FE amplitude drop occur. Since the tracking servo and the focus servo are performed based on the amplitude of the TE signal and the FE signal, respectively, when the TE amplitude decrease and the FE amplitude decrease occur, the feedback gain used for the servo decreases, and the recording characteristics and the reproduction characteristics deteriorate. Thus, in the worst case, there is a problem that tracking servo and focus servo are not applied.

  The present invention has been made to solve the above-described problems, and the amplitudes of the tracking error signal and the focus error signal due to factors such as the influence of disturbances such as a temperature rise and the reflectance of the optical disk differ depending on the track position. A tracking control method and a focus control method that can perform stable tracking servo and focus servo by correcting the amplitude of the tracking error signal and focus error signal to be constant even when fluctuations may occur. It is an object of the present invention to provide an optical disc apparatus having improved recording and reproduction quality using the tracking control method and the focus control method.

  The present invention has been made to solve the above-described problems, and measures the peak level and the bottom level of a tracking error signal when performing a track jump operation or a seek operation, and determines the difference between the peak level and the bottom level. Is a tracking control method characterized in that the amplitude of the tracking error signal is adjusted so that becomes a constant value, and a focus error signal is used when performing an interlayer jump in a multi-layer disc on which a plurality of recording surfaces are formed. The focus control method is characterized in that the peak level and the bottom level are measured, and the amplitude of the focus error signal is adjusted so that the difference between the peak level and the bottom level becomes a constant value.

According to the present invention, even if the tracking error signal and the focus error signal may fluctuate in amplitude due to the influence of a disturbance such as a temperature rise or the reflectivity of the optical disk varies depending on the track position, the tracking error signal Since the amplitude of the focus error signal is corrected to be constant, stable tracking servo and focus servo can be applied.

  According to the present invention, even if the tracking error signal and the focus error signal may fluctuate in amplitude due to the influence of disturbance such as a temperature rise or the reflectivity of the optical disk varies depending on the track position, the tracking error signal Since the amplitude of the focus error signal is corrected to be constant, stable tracking servo and focus servo can be applied.

  Therefore, by using this tracking control method and focus control method, an optical disc apparatus with improved recording / reproduction quality can be realized.

  According to the first aspect of the present invention, when the track jump operation is performed at an arbitrary position on the optical disc, the peak level and the bottom level of the tracking error signal are measured, and the difference between the peak level and the bottom level is a constant value. The tracking control method is characterized in that the amplitude of the tracking error signal is adjusted so that

  According to the present invention, the amplitude of the tracking error signal is constant even when the amplitude of the tracking error signal may fluctuate due to the influence of a disturbance such as a temperature rise or the reflectivity of the optical disc varies depending on the track position. Therefore, stable tracking servo can be applied when performing a track jump operation.

  The invention according to claim 2 of the present invention measures the peak level and the bottom level of the tracking error signal when performing a seek operation to access the target position of the optical disc, and determines the difference between the peak level and the bottom level. The tracking control method is characterized in that the amplitude of the tracking error signal is adjusted so that becomes a constant value.

  According to the present invention, the amplitude of the tracking error signal is constant even when the amplitude of the tracking error signal may fluctuate due to the influence of a disturbance such as a temperature rise or the reflectivity of the optical disc varies depending on the track position. Therefore, stable tracking servo can be applied when performing a seek operation.

  According to a third aspect of the present invention, in the tracking control method according to the first or second aspect, when a track jump is performed at a boundary between a recorded area and an unrecorded area of the optical disc, the tracking error signal A tracking error signal is generated without adjusting the amplitude.

  At the boundary between the recorded area and unrecorded area of the optical disc, the amount of reflected light is affected by the spread of the spot diameter of the laser beam irradiated to the position where the pit is formed, and the received light level of the detector fluctuates, resulting in a tracking error. Although the signal is distorted, according to the present invention, when performing a track jump at the boundary between the recorded area and the unrecorded area, which is a special area, the amplitude of the tracking error signal is not adjusted. Since the tracking error signal is generated, the tracking error signal can be generated without being affected by the boundary portion.

The invention according to claim 4 of the present invention measures a peak level and a bottom level of a focus error signal when performing an interlayer jump in a multi-layer disc in which a plurality of recording surfaces are formed,
In this focus control method, the amplitude of the focus error signal is adjusted so that the difference between the peak level and the bottom level becomes a constant value.

  According to the present invention, the amplitude of the focus error signal is constant even when the amplitude of the tracking error signal may fluctuate due to the influence of a disturbance such as a temperature rise or the reflectivity of the optical disc varies depending on the track position. Therefore, stable focus servo can be applied when performing an interlayer jump.

  According to a fifth aspect of the present invention, when a track jump operation is performed at an arbitrary position on an optical disc, a peak detection circuit that measures the peak level of the tracking error signal, and a bottom that measures the bottom level of the tracking error signal. An optical disc apparatus comprising a detection circuit and having a signal calculation unit for adjusting an amplitude of a tracking error signal so that a difference between a peak level and a bottom level becomes a constant value.

  According to the present invention, the amplitude of the tracking error signal is constant even when the amplitude of the tracking error signal may fluctuate due to the influence of a disturbance such as a temperature rise or the reflectivity of the optical disc varies depending on the track position. Therefore, it is possible to realize an optical disc apparatus capable of performing stable tracking servo when performing a track jump operation.

  According to a sixth aspect of the present invention, there is provided a peak detection circuit for measuring a peak level of the tracking error signal when performing a seek operation to access a target position of the optical disc, and a bottom level of the tracking error signal. An optical disc apparatus comprising a signal detection unit that adjusts the amplitude of the tracking error signal so that the difference between the peak level and the bottom level becomes a constant value.

  According to the present invention, the amplitude of the tracking error signal is constant even when the amplitude of the tracking error signal may fluctuate due to the influence of a disturbance such as a temperature rise or the reflectivity of the optical disc varies depending on the track position. Therefore, it is possible to realize an optical disc apparatus capable of performing stable tracking servo when performing a seek operation.

  According to a seventh aspect of the present invention, in the optical disk device according to the fifth or sixth aspect, when performing a track jump at a boundary between a recorded area and an unrecorded area of the optical disk, the signal calculation section The tracking error signal is generated without adjusting the amplitude of the tracking error signal.

  According to the present invention, when performing a track jump at the boundary between the recorded area and the unrecorded area, which is a special area, the tracking error signal is generated without adjusting the amplitude of the tracking error signal. A tracking error signal can be generated without being affected by the boundary.

  According to an eighth aspect of the present invention, there is provided a peak detection circuit for measuring a peak level of a focus error signal when performing an interlayer jump on a multi-layer disc having a plurality of recording surfaces, and a bottom level of the focus error signal. And a signal detector that adjusts the amplitude of the focus error signal so that the difference between the peak level and the bottom level becomes a constant value.

According to the present invention, the amplitude of the focus error signal is constant even when the amplitude of the tracking error signal may fluctuate due to the influence of disturbance such as a temperature rise and the reflectivity of the optical disc varies depending on the track position. Therefore, an optical disc apparatus capable of performing stable focus servo when performing an interlayer jump can be realized.

(Embodiment 1)
The configuration of the optical disc apparatus according to the embodiment of the present invention will be described with reference to FIG.

  In FIG. 1, the optical disk apparatus according to the present embodiment includes an optical pickup 2 that irradiates an optical disk 1 with laser light and receives light reflected by the optical disk 1, and a reflection from the optical disk 1 obtained by the optical pickup 2. A detector 3 that converts light into current and outputs a signal for reading data from the optical disc 1, an output signal for detecting a focus error, and an output signal for detecting a tracking error; and a tracking error signal output from the detector 3; The signal calculation unit 4 generates a focus error signal.

  The TE signal and the FE signal are input from the signal calculation unit 4 to the digital servo processor (DSP) 7. The DSP 7 controls the tracking actuator 6 that drives the optical pickup 2 so that the optical pickup 2 follows the track of the optical disc 1 on the basis of the TE signal, and between the objective lens provided in the optical pickup 2 and the optical disc 1. The focus actuator 5 is controlled so that the distance between them is appropriate.

  The above processing of the DSP 7 is executed under the control of the CPU 8.

  A means for generating a tracking error signal and a focus error signal from the output signal output from the detector 3 will be described with reference to FIGS.

  FIG. 2 shows a signal TR + and a signal TR− obtained by irradiating a pit 22 formed on the track center 21 of the optical disk shown in FIG. 10 with a laser beam and receiving reflected light from the pit 22 by detectors 24 and 25. The configuration of the circuit for generating the TE signal by adjusting the amplitude of the TE signal will be described.

  In FIG. 2, the difference between the signal TR + obtained by receiving half of the spot 23 of the laser beam by the detector 24 and the signal TR− obtained by receiving the other half of the spot 23 by the detector 25 is the difference. The TE attenuator 9 adjusts the amplitude of the TE signal to be constant and generates the TE signal.

  In addition, a Peak detection circuit 11 and a Bottom detection circuit 12 are provided. The Peak detection circuit 11 detects the peak level of the TE signal, and the Bottom detection circuit 12 detects the bottom level of the TE signal.

  3 generates an FE signal by adjusting the amplitude of the FE signal from the signal FE + and the signal FE− obtained by irradiating the pit 22 formed on the track center 21 of the optical disc shown in FIG. 10 with laser light. A circuit configuration is shown.

  In FIG. 3, the difference between the signal FE + obtained by receiving half of the spot 23 of the laser beam by the detector 24 and the signal FE− obtained by receiving the other half of the spot 23 by the detector 25 is the difference. Then, the FE attenuator 10 adjusts the amplitude of the FE signal to be constant and generates an FE signal.

In addition, a Peak detection circuit 13 and a Bottom detection circuit 14 are provided. The Peak detection circuit 13 detects the peak level of the FE signal, and the Bottom detection circuit 14 detects the bottom level of the FE signal.

  FIG. 4 shows an example of a waveform of the TE signal when the still operation is performed. The TE signal has a level difference up to the peak level based on the DC level and a level difference up to the bottom level due to factors such as variations in the sensitivity of the detector due to the influence of disturbance and the like.

  FIG. 5 shows an example of a waveform of the TE signal when the seek operation is performed. When the seek operation is performed, the waveform jumps greatly in the tracking direction, so that a waveform as shown in FIG. 5 is obtained. In this case as well, the TE signal is based on the DC level if there is an influence of disturbance or the like. The level difference up to the peak level is different from the level difference up to the bottom level.

  FIG. 6 shows an example of a waveform of an FE signal when an interlayer jump is performed on a two-layer disc as an example of a multi-layer disc on which a plurality of recording surfaces are formed. For the FE signal at the time of the interlayer jump, if there is an influence of disturbance or the like, the level difference up to the peak level based on the DC level and the level difference up to the bottom level due to factors such as variations in detector sensitivity. Have different waveforms.

  Hereinafter, a process for adjusting the amplitude so that the amplitudes of the TE signal and the FE signal become constant values will be described with reference to FIGS. 7, 8, and 9. Processing for adjusting the amplitudes of the TE signal and the FE signal described below is executed by the signal calculation unit 4.

  FIG. 7 shows a flowchart of a process for correcting the amplitude of the TE signal to be constant when performing the still operation.

After the detection circuit is initialized (S1), the track jump is performed (S2), and the peak level and the bottom level of the TE signal are measured (S3). Based on the measured peak level and bottom level, the TE signal amplitude (TEpp) is obtained by calculating TE signal amplitude (TEpp) = peak level−bottom level (S4).

Next, for the target level that is the target value of the amplitude of the TE signal,
TEATT = target level / TEpp
The attenuation value TEATT of the TE signal is obtained by performing the above calculation (S5).

  With the above processing, even when the TE signal amplitude fluctuation may occur when performing the still operation, the TE signal amplitude is corrected to be constant, so that stable tracking servo can be applied. It becomes possible.

  Note that by replacing step S2 in the flowchart shown in FIG. 7 with a track seek, correction can be made so that the amplitude of the TE signal when performing a seek operation is constant. As a result, even when the amplitude fluctuation of the TE signal may occur during the seek operation, the TE signal amplitude is corrected to be constant, so that stable tracking servo can be applied. Become.

  FIG. 8 shows a flowchart of processing for correcting the amplitude of the TE signal to be constant in consideration of the track jump at the boundary between the recorded area and the unrecorded area of the optical disc.

At the boundary between the recorded area and the unrecorded area of the optical disc, the amount of reflected light is affected by the spread of the spot diameter of the laser beam irradiated to the position where the pits 22 are formed, and the light receiving levels of the detectors 24 and 25 are changed. It fluctuates and the TE signal is distorted.

  In this way, at the boundary between the recorded area and the unrecorded area of the optical disc, in addition to factors such as the influence of disturbance such as temperature rise and the reflectivity of the optical disc differing depending on the track position, different special The TE signal amplitude is affected by various factors. Therefore, an additional means for adjusting the TE signal by controlling the focus direction is necessary at the boundary between the recorded area and the unrecorded area of the optical disc, and it is not preferable to apply the process shown in FIG. 7 as it is. . The processing method shown in FIG. 8 takes this into consideration.

After the detection circuit is initialized (S11), the track jump is performed (S12), and it is determined whether or not the track jump position is a boundary between the recorded area and the unrecorded area of the optical disc (S13). . When the track jump position is not the boundary between the recorded area and the unrecorded area of the optical disc, the peak level and the bottom level of the TE signal are measured (S14). Based on the measured peak level and bottom level,
The TE signal amplitude (TEpp) = peak level-bottom level is calculated to obtain the TE signal amplitude (TEpp) (S15).

Next, for the target level that is the target value of the amplitude of the TE signal,
TEATT = target level / TEpp
The attenuation value TEATT is obtained by performing the above calculation (S16).

  On the other hand, if the track jump position is the boundary between the recorded area and the unrecorded area of the optical disc, the process ends without adjusting the amplitude of the TE signal shown in S14 to S16.

  By the above processing, the track jump in a special area called the boundary between the recorded area and the unrecorded area is excluded, and correction is made so that the amplitude of the TE signal becomes constant. It is possible to apply a stable tracking servo without receiving.

  FIG. 9 shows a flowchart of processing for correcting the amplitude of the FE signal to be constant when performing an interlayer jump in a multi-layer disc formed with a plurality of recording surfaces.

After initializing the detection circuit (S21), jump between layers (S22), and measure the peak level and bottom level of the FE signal (S23). Based on the measured peak level and bottom level,
The FE signal amplitude (FEpp) = peak level−bottom level is calculated to obtain the FE signal amplitude (FEpp) (S24).

Next, for the target level that is the target value of the amplitude of the FE signal,
FEATT = target level / FEpp
The attenuation value FEATT is obtained by performing the above calculation (S25).

  Through the above processing, when performing an interlayer jump in a multi-layer disc on which a plurality of recording surfaces are formed, the amplitude of the FE signal is corrected so as to be constant even when the amplitude fluctuation of the FE signal may occur. Therefore, stable tracking servo can be applied. The above processing is not limited to a dual-layer disc, and can be applied to a case where an FE signal is generated by performing an interlayer jump between a plurality of recording surfaces in a multilayer disc on which an arbitrary number of recording surfaces are formed. .

  INDUSTRIAL APPLICABILITY The present invention can be used as an optical disk device that records and reproduces information on an optical disk with an optical pickup, and can realize an optical disk device with improved recording and reproduction quality.

The figure which shows the constitution of the optical disk device Diagram showing means for generating tracking error signal Diagram showing means for generating a focus error signal The figure which shows an example of the waveform of TE signal in still operation The figure which shows an example of the waveform of TE signal in seek operation The figure which shows an example of the waveform of the FE signal at the time of an interlayer jump Flow chart of processing for correcting the TE signal amplitude to be constant Flowchart of processing for correcting the amplitude of the TE signal to be constant in consideration of the track jump at the boundary between the recorded area and the unrecorded area of the optical disc Flow chart of processing for correcting the amplitude of the FE signal to be constant The figure which shows the operation which irradiates the laser beam to the pit formed on the track center of the optical disk and receives the reflected light by the pit with the detector A diagram showing a conventional means for generating a tracking error signal and a means for generating a focus error signal

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical disk 2 Optical pick-up 3 Detector 4 Signal calculating part 5 Focus actuator 6 Tracking actuator 7 DSP
8 CPU
9 TE attenuator 10 FE attenuator 11 Peak detector circuit 12 Bottom detector circuit 13 Peak detector circuit 14 Bottom detector circuit 21 Track center 22 Pit 23 Spot 24 Detector 25 Detector 25

Claims (8)

When performing a track jump operation at an arbitrary position on the optical disc, the peak level and bottom level of the tracking error signal are measured, and the amplitude of the tracking error signal is adjusted so that the difference between the peak level and the bottom level becomes a constant value. The tracking control method characterized by performing. When performing a seek operation to access the target position on the optical disc, the peak level and bottom level of the tracking error signal are measured, and the tracking error signal is set so that the difference between the peak level and the bottom level is a constant value. A tracking control method characterized in that the amplitude adjustment is performed. 3. The tracking error signal is generated without adjusting the amplitude of the tracking error signal when performing a track jump at the boundary between the recorded area and the unrecorded area of the optical disk. Tracking control method. When performing an interlayer jump on a multi-layer disc with multiple recording surfaces, measure the peak level and bottom level of the focus error signal so that the difference between the peak level and bottom level is a constant value. A focus control method characterized in that the amplitude adjustment is performed. When performing a track jump operation at an arbitrary position on the optical disc, the optical disc has a peak detection circuit for measuring the peak level of the tracking error signal and a bottom detection circuit for measuring the bottom level of the tracking error signal. An optical disc apparatus comprising a signal calculation unit that adjusts an amplitude of a tracking error signal so that a difference between a level and a constant value is constant. A peak detection circuit for measuring the peak level of the tracking error signal and a bottom detection circuit for measuring the bottom level of the tracking error signal when performing a seek operation to access a target position of the optical disc; An optical disc apparatus comprising a signal calculation unit that adjusts an amplitude of a tracking error signal so that a difference between a peak level and a bottom level becomes a constant value. When performing a track jump at a boundary portion between a recorded area and an unrecorded area of an optical disc, the signal calculation section generates a tracking error signal without adjusting the amplitude of the tracking error signal. Item 7. The optical disk device according to Item 5 or 6. When performing an interlayer jump in a multi-layer disc formed with a plurality of recording surfaces, a peak detection circuit that measures the peak level of the focus error signal, and a bottom detection circuit that measures the bottom level of the focus error signal, An optical disc apparatus comprising a signal calculation unit for adjusting an amplitude of a focus error signal so that a difference between a peak level and a bottom level becomes a constant value.

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