JP2005071472A - Laser drive signal control method of optical disk recording and reproducing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser drive signal control method of an optical disk recording and reproducing device performing recording and reproducing operation of a signal for a disk from an optical pickup. <P>SOLUTION: This device comprises an erasing period sampling circuit 7 sampling a RF signal of an erasing period in a RF signal obtained from an optical detector 3, a signal level detecting circuit 8 detecting a level of the RF signal obtained by the sampling circuit 7, a control circuit 6 setting a level of a drive signal supplied to a laser diode 1, a temperature detecting circuit 14 detecting temperature of an optical pickup, and a compensation value memory circuit 15 in which a compensation value for temperature is stored. servo operation is performed for a circuit outputting an erasure level signal to keep a signal level detected by the signal level detecting circuit 8 constant, while level compensation operation for a circuit outputting an erasure level signal based on a compensation value corresponding to temperature is performed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical disk recording / reproducing apparatus configured to record a signal on a disk with a laser beam irradiated from an optical pickup and perform a reproducing operation of the signal recorded on the disk with the laser beam.

  Disc players that use optical pickups to read signals recorded on discs have become widespread, but recently, in addition to playback functions, signals are recorded on discs using laser light emitted from optical pickups. An optical disc recording / reproducing apparatus configured so as to be able to be used has been commercialized.

  As such an optical disk recording / reproducing apparatus, a method called “overwrite” which can be rewritten by overwriting the disk is generally used, and a CD-RW type recording / reproducing apparatus using a CD type recording disk is widely spread. Yes. In such an overwrite type optical disk recording / reproducing apparatus, a laser diode incorporated in an optical pickup is converted into a drive signal called a multi-pulse consisting of an erase level value E, a peak level value P and a bottom level value B shown in FIG. And is lit to record a signal on a disk.

In an optical disk recording / reproducing apparatus that records a signal on a disk by driving a laser diode to light with such a multi-pulse waveform drive signal, the erase level value E, the peak level value P, and the bottom level value B are accurately controlled. A technique for performing a high-quality recording operation on a disc has been developed (see, for example, Patent Document 1).
JP 2001-34987 A

  In an optical disc recording / reproducing apparatus that records a signal on a disc by driving a laser diode with a multi-pulse waveform drive signal, a value BP from a bottom level value B to a peak level value P and a bottom level value B It is necessary to adjust the ε value, which is the ratio (BE / BP) to the value BE up to the erasure level E, and this ε value is unique to the disc and is determined according to the recording speed.

  In the case of a CD-RW device, the ε value is usually determined before adjusting the laser output of the disc, but this value is set by extracting data information representing the disc characteristics recorded on the disc.

  In order to accurately record the signal on the disc, it is necessary to control the output of the laser beam emitted from the laser diode. Conventionally, the monitor is used to monitor the level of the laser beam emitted from the laser diode. A diode is provided, and the output of the laser beam is adjusted using a monitor signal obtained from the monitor diode.

  According to such a configuration, although it is possible to accurately perform the laser light output control operation, it is necessary to provide a monitoring diode in the optical pickup, and thus there is a problem that the price of the optical pickup becomes expensive. In order to reduce the price of the optical pickup, the monitoring diode has been removed.

  Also, when using an optical pickup that does not have a monitor diode, the laser drive signal level control operation is performed using the level change of the laser light reflected from the disk. The laser beam level is affected by the characteristics of the disk and the laser output changes due to the temperature of the laser diode. Therefore, the laser drive signal cannot be controlled accurately.

  The present invention is intended to provide a method for controlling a laser drive signal that can solve such a problem.

  The present invention includes a photodetector that is incorporated in an optical pickup and converts laser light reflected from a disk into an electrical signal, and an RF signal obtained from the photodetector is input and amplifies the signal. RF signal amplifying circuit, erasing period sampling circuit for sampling the RF signal in the erasing period in the RF signal output from the RF signal amplifying circuit, and signal level detection for detecting the level of the RF signal obtained from the sampling circuit A circuit, a control circuit for setting an erase level value, a peak level value and a bottom level value of a drive signal supplied to the laser diode, a temperature detection circuit for detecting the temperature of the optical pickup, and a correction value for the temperature are stored. The signal level detected by the signal level detection circuit is made constant. It is configured to based on the correction value corresponding to the temperature performing level correction operation for the circuit which outputs an erase level signal performs servo operation for the circuit which outputs an erase level signal to.

  According to the laser drive signal control method of the present invention, since the monitoring diode for monitoring the light emission output of the laser diode is not required for the optical pickup, the price of the optical pickup can be reduced.

  In the present invention, the temperature detection circuit for detecting the temperature of the optical pickup is provided, and the erase level controlled to control the laser output in accordance with the temperature is corrected. Can be performed accurately.

  In the present invention, since the peak level value and the bottom level value are set based on the erase level controlled to control the laser output, the laser drive signal for accurately performing the recording operation is generated. Can be done.

  The present invention eliminates an RF signal that is a signal reflected from a disk in order to control the laser output of an optical pickup that does not include a monitoring diode that monitors the output level of laser light emitted from the laser diode. The level of the period is used.

  FIG. 1 is a circuit diagram showing an embodiment of an optical disk recording / reproducing apparatus according to the present invention, and FIG. 2 is a waveform diagram for explaining the operation of the present invention.

In FIG. 1, reference numeral 1 denotes a laser diode that is incorporated in an optical pickup and emits laser light, and is connected to be driven by a current supplied from a laser driving circuit 2. Reference numeral 3 denotes a photodetector that receives the laser light irradiated from the laser diode 1 and reflected from the disk 4, and has a function of converting the laser light into an electric signal.

  Reference numeral 5 denotes an RF signal amplification circuit that receives an RF signal (high frequency signal) converted into an electrical signal by the photodetector 3 and amplifies the signal. FIG. 2 shows the waveform of the laser drive signal supplied to the laser diode 1, and the period R during which the drive signal changing between the peak level value P and the bottom level value B is supplied to the disk 4. A recording period in which a signal is recorded is shown, and a period S in which a signal having an erasing level value E is supplied shows an erasing period. That is, a signal recording operation to the disk 4 is performed in the period R, and a signal erasing operation is performed in the period S.

  Reference numeral 6 denotes a control circuit that performs a control operation such as a laser drive signal control operation, which will be described later. Reference numeral 7 denotes an erasing period sampling circuit whose operation is controlled by the control circuit 6, and an RF signal output from the RF signal amplification circuit 5 Is input, and an RF signal obtained during the period S which is an erasing period is sampled and output. A signal level detection circuit 8 receives a signal sampled by the erasing period sampling circuit 7 and detects the level of the signal. The signal level detection circuit 8 is configured to output a detection signal to the control circuit 6.

  Reference numeral 9 denotes a peak level signal output circuit whose operation is controlled by the control circuit 6, and is set to output a signal for causing the laser drive circuit 2 to output a signal having a peak level value P for recording a signal on the disk. . Reference numeral 10 denotes a bottom level signal output circuit whose operation is controlled by the control circuit 6 and is set to output a signal for causing the laser drive circuit 2 to output a signal having a bottom level value B. An erasure level signal output circuit 11 whose operation is controlled by the control circuit 6 is set so as to output a signal for causing the laser drive circuit 2 to output a signal of the erasure level value E.

  A servo circuit 12 performs a servo operation on the erase level signal output circuit 11 so as to make the level of the signal obtained from the signal level detection circuit 8, that is, the level of the RF signal obtained in the erase period constant.

  Reference numeral 13 denotes an adder circuit to which the output signals of the peak level signal output circuit 9, the bottom level signal output circuit 10 and the erase level signal output circuit 11 are input. Selective addition of signals input by the control operation of the control circuit 6 An operation is performed, and the selectively added signal is supplied to the laser driving circuit 2.

  Reference numeral 14 denotes a temperature detection circuit incorporating a temperature detection element (not shown), which is connected to detect the temperature of the optical pickup and to output the detection output to the control circuit 6. A correction value memory circuit 15 stores a correction value for the erasure level signal output circuit 11 corresponding to the temperature detected by the temperature detection circuit 14. The correction value stored in the correction value memory circuit 15 is set to a value for correcting the change because the output characteristic of the laser diode 1 changes according to the temperature.

In such a configuration, the laser light emitted from the laser diode 1 is reflected from the disk 4 and received by the photodetector 3, and an RF signal corresponding to the output is output. Since the erasing period RF signal is sampled by the erasing period sampling circuit 7, the level of the erasing period RF signal is monitored. A monitor signal, which is an RF signal obtained by sampling by the erasing period sampling circuit 7, is input to the signal level detection circuit 8, the level of which is detected, and then input to the control circuit 6. When such a monitor signal is input, the control circuit 6 causes the erase level signal output circuit 11 to make the level of the signal detected by the signal level detection circuit 8 constant by the servo operation by the servo circuit 12. The level of the output signal, that is, the erase level value E is controlled.

  Also, the temperature detection operation of the optical pickup by the temperature detection circuit 14 is performed, and a correction value corresponding to the detected temperature is read from the correction value memory circuit 15 and an erase level signal output circuit is read based on the read correction value. 11 is configured to correct the level value output from the control unit 11.

  As described above, the optical disk recording / reproducing apparatus according to the present invention is configured. Next, the operation will be described. Data information representing the characteristics of the disk is extracted based on the ATIP signal obtained from the pre-groove provided on the disk, and the erase level value E, peak level value P, and bottom level value B are selected from the extracted data information. Set. Each of these values is selected and set based on data stored in advance in a ROM or the like incorporated in the control circuit 6 as is generally done.

  When such a setting operation is performed, the peak level value P, the bottom level value B, and the erase level are respectively output from the peak level signal output circuit 9, the bottom level signal output circuit 10, and the erase level signal output circuit 11 by the control operation of the control circuit 6. A control operation for outputting a signal of value E from the laser driving circuit 2 is performed.

  Then, the control circuit 6 performs the selective addition control operation of the adder circuit 13 in accordance with the input recording signal, and the signal subjected to the selective addition control is supplied to the laser drive circuit 2. As a result, the drive signal having the waveform shown in FIG. 2 from the laser drive circuit 2, that is, the drive waveform having the peak level value P and the bottom level value B is supplied to the laser diode 1 in the recording period R, and the erase level value E Is supplied to the laser diode 1 during the period S, which is the erasing period. Then, the period R and the period S in which the laser driving signal having such a pulse waveform is output are changed according to the length of the recording signal.

  As described above, the laser drive signal generation operation in the recording operation state is performed. During the recording operation, the erase level value E is determined by the reflected signal detection operation by the photodetector 3, the amplification operation by the RF signal amplification circuit 5, The RF signal level in the erase period S is controlled to be constant by the sampling operation by the erase period sampling circuit 7, the detection operation of the erase period signal by the signal level detection circuit 8, and the servo operation by the servo circuit 12. Accordingly, an operation for controlling the erase level value E is performed so that a desired laser output can be obtained even if the level of the laser light irradiated from the laser diode 1 changes due to a temperature change or the like in the recording operation state. It will be.

  As described above, the normal servo operation by the servo circuit 12 is performed. When such an operation is performed, the temperature detection operation of the optical pickup by the temperature detection circuit 14 is performed. Then, a correction value corresponding to the temperature detected by the temperature detection circuit 14 is read from the correction value memory circuit 15, and an operation for correcting the output level of the erasure level signal output circuit 11 based on the correction value is performed. Is called. Such a correction operation or the like can be performed by digital signal processing by the control circuit 6.

As described above, various control operations are performed on the erase level value E. The peak level value P and the bottom level value B are controlled according to the change of the erase level value E with the erase level value E as a reference. Operation will be performed. The adjustment operation of the peak level value P and the bottom level value B is performed based on the ε value set by the characteristics of the disk 4. Accordingly, when the erase level value E is changed to keep the level of the erase period in the RF signal constant, the peak level value P and the bottom level value B are changed in accordance with the change, so that the recording operation is performed. Therefore, it is possible to perform a drive signal generation operation suitable for this.

  As described above, the control operation of the laser drive signal in the recording operation state is performed. However, when the switching operation from the recording state to the reproduction state is performed, the level of the drive signal supplied to the laser diode 1 is set. The signal level is changed to the signal level for the reproduction operation. In such a case, the reproduction is performed in accordance with the level change adjusted during the recording operation described above with respect to the laser output for performing the reproduction operation set in advance. If the laser output for this is changed, a laser output suitable for performing the reproducing operation can be obtained.

It is a circuit diagram which shows one Example of the optical disk recording / reproducing apparatus based on this invention. It is a wave form diagram for demonstrating operation | movement of this invention.

Explanation of symbols

1 Laser diode
2 Laser drive circuit
3 Photodetector
5 RF signal amplification circuit
6 Control circuit
7 Erase period sampling circuit
8 Signal level detection circuit
9 Peak level signal output circuit 10 Bottom level signal output circuit 11 Erase level signal output circuit 12 Servo circuit 13 Adder circuit 14 Temperature detection circuit 15 Correction value memory circuit

Claims (3)

In an optical disk recording / reproducing apparatus configured to record a signal on a disk by lighting a laser diode incorporated in an optical pickup with a driving signal composed of an erase level value, a peak level value, and a bottom level value, A photodetector that is incorporated in an optical pickup and converts laser light reflected from a disk into an electrical signal, and an RF signal amplification circuit that receives an RF signal obtained from the photodetector and amplifies the signal An erasing period sampling circuit that samples an RF signal in an erasing period in the RF signal output from the RF signal amplification circuit, a signal level detection circuit that detects the level of the RF signal obtained from the sampling circuit, and a laser Erase level value and peak level of the drive signal supplied to the diode And a control circuit that sets the bottom level value, a temperature detection circuit that detects the temperature of the optical pickup, and a correction value memory circuit that stores a correction value for the temperature, and is detected by the signal level detection circuit. Servo operation is performed on a circuit that outputs an erasure level signal to make the signal level constant, and level correction operation is performed on a circuit that outputs an erasure level signal based on a correction value corresponding to temperature. A laser drive signal control method for an optical disk recording / reproducing apparatus. 2. The laser drive signal control method according to claim 1, wherein the peak level value and the bottom level value are set based on the erase level. 3. The laser drive signal control method according to claim 2, wherein the peak level value and the bottom level value are set based on an ε value.

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