JP2005050451A - Laser drive signal control method for optical disk recording/reproducing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser drive signal control method for an optical disk recording and reproducing device which performs recording/reproducing operation of signals to from a disk by an optical pickup. <P>SOLUTION: This device is composed of: an amplifier circuit 5 for optical detector which amplifies a signal obtained from an optical detector 3; a signal level detection circuit 10 which detects a level of a signal obtained from an erasing period sampling circuit 9 sampling a signal in an erasing period in a signal outputted from the amplifier circuit 5; and a control circuit 8 which sets a level of a drive signal supplied to a laser diode 1 and controls operation of a memory circuit 16 in which reflectance data corresponding to a property of a disk 4 is stored. Thus, the device detects kinds of the disk 4, sets gain of the amplifier circuit 5 based on reflectance data in accordance with a detected kind, and performs servo operation for a circuit to which an erasing level signal is outputted to keep a signal level detected by the signal level detection circuit 10 constant. <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 an optical pickup to read out the signals recorded on the disc have become widespread, but recently, in addition to the playback function, signals are recorded on the disc by laser light emitted from the optical pickup. An optical disk 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, the laser diode incorporated in the optical pickup is driven by 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. It is configured to drive the light and record the signal on the 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 signals on a disc by driving a laser diode with a pulse signal having a multi-pulse waveform, 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 beam 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.

  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 that converts laser light reflected from a disk into an electrical signal, an amplifying circuit for a photodetector that amplifies a signal obtained from the photodetector, An erasing period sampling circuit that samples a signal in the erasing period in a signal output from the amplification circuit for photodetectors, a signal level detection circuit that detects the level of the signal obtained from the erasing period sampling circuit, and a laser diode It consists of a control circuit that controls the operation of the memory circuit that sets the erase level value, peak level value and bottom level value of the pulse signal to be recorded and stores the reflectance data corresponding to the characteristics of the disk, and the disk is loaded The type of the disc is detected and the reflectance data according to the detected type is used. Set the gain of detector amplifier circuit is configured to perform a servo operation for the circuit which outputs an erase level signal to a constant signal level detected by said signal level detecting circuit.

  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.

  Further, according to the present invention, the gain of the photodetector amplifying circuit for amplifying the signal obtained from the photodetector is set based on the reflectance data of the disk, so that the signal level for performing the servo operation with respect to the erase level Can be accurately performed, and the control operation of the laser drive signal can be accurately performed.

  In the present invention, since the peak level value and the bottom level value are set based on the erase level servo controlled to control the laser output, the generation of the laser drive signal for accurately performing the recording operation The operation can be performed.

  In the present invention, the level of the erasing period in the signal reflected from the disk is controlled in order to control the laser output of an optical pickup that does not have a monitoring diode for monitoring the output level of laser light emitted from the laser diode. It is intended to be 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 electrical signal. Reference numeral 5 denotes a photodetector amplifying circuit that receives a signal converted into an electric signal by the photodetector 3 and amplifies the signal, and is configured such that the gain is controlled by the gain control circuit 6. .

Reference numeral 7 denotes an RF signal amplification circuit that receives the RF signal (high frequency signal) amplified by the photodetector amplification circuit 5 and amplifies the signal. FIG. 2 shows a waveform of a laser drive signal supplied to the laser diode 1, and a period R during which a pulse signal changing between the peak level value P and the bottom level value is supplied to the disk 4. The period S during which the signal of the erase level value E is supplied indicates the erase 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 8 denotes a control circuit that performs a control operation such as a laser drive signal control operation, which will be described later. Reference numeral 9 denotes an erasing period sampling circuit whose operation is controlled by the control circuit 8. Is input, and an RF signal obtained during the period S which is an erasing period is sampled and output. Reference numeral 10 denotes a signal level detection circuit that receives the signal sampled by the erase period sampling circuit 9 and detects the level of the signal, and is configured to output a detection signal to the control circuit 8.

  Reference numeral 11 denotes a peak level signal output circuit whose operation is controlled by the control circuit 8 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 4. Yes. A bottom level signal output circuit 12 whose operation is controlled by the control circuit 8 is set to output a signal for causing the laser drive circuit 2 to output a signal of the bottom level value B. An erasure level signal output circuit 13 whose operation is controlled by the control circuit 8 is set to output a signal for causing the laser drive circuit 2 to output a signal of the erasure level value E.

  A servo circuit 14 performs a servo operation on the erase level signal output circuit 13 so as to make the level of the signal obtained from the signal level detection circuit 10, that is, the level of the RF signal obtained in the erase period constant.

  Reference numeral 15 denotes an adder circuit to which the output signals of the peak level signal output circuit 11, bottom level signal output circuit 12 and erase level signal output circuit 13 are input. Selective addition of signals input by the control operation of the control circuit 8 An operation is performed, and the selectively added signal is supplied to the laser driving circuit 2.

  Reference numeral 16 denotes a memory circuit in which reflectivity data corresponding to the type of the disk 4 is stored as table data, and the data reading operation is controlled by the control circuit 8.

  In such a configuration, when the disc 4 is mounted on the disc mounting portion provided in the optical disc recording / reproducing apparatus, an operation of reading data indicating the type of the disc recorded on the inner peripheral portion of the disc 4 is performed. A control operation for reading the data of the corresponding reflectance from the memory circuit 16 is performed. When such a control operation is performed, a control operation for the gain control circuit 6 is performed based on the reflectance data, and a gain setting operation of the photodetector amplifying circuit 5 is performed. That is, when the reflectivity of the disk 4 is low, the gain of the photodetector amplifying circuit 5 is increased. On the contrary, when the reflectivity is high, the gain of the photodetector amplifying circuit 5 is decreased. Control action is performed.

In such a configuration, the laser light emitted from the laser diode 1 during the recording operation is reflected from the disk 4 and received by the photodetector 3, and the gain for the photodetector is adjusted and set by the gain control circuit 6. An RF signal corresponding to the output is output from the circuit 5. The RF signal output from the photodetector amplifying circuit 5 is amplified by the RF signal amplifying circuit 7 and then input to the erasing period sampling circuit 9. As a result, a sampling control operation for the erasing period sampling circuit 9 by the control circuit 8 is performed,
The RF signal in the erase period is sampled. Therefore, in the recording operation state, the level of the RF signal during the erasing period is constantly monitored. A monitor signal, which is an RF signal sampled by the erasing period sampling circuit 9, is input to the signal level detection circuit 10, and the level is detected, and then input to the control circuit 8. When such a monitor signal is input, the control circuit 8 maintains the level of the signal output from the erase level signal output circuit 13 by the servo operation by the servo circuit 14, that is, the erase level value E at a constant level. It is configured to control as much as possible.

  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 characteristics corresponding to the type of the disk is extracted based on the ATIP signal obtained from the pregroove provided on the disk 4, and the preset erase level value B and peak are extracted from the extracted data information. The level value P and the bottom level value B are selected and set, the reflectance data stored in the memory circuit 16 is read, the gain control circuit 6 is controlled based on the data, and the gain setting for the photodetector amplifying circuit 5 is performed. Perform the action.

  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 11, the bottom level signal output circuit 12, and the erase level signal output circuit 13 by the control operation of the control circuit 8. A control operation for outputting a signal of value E from the laser driving circuit 2 is performed.

  Then, the control circuit 8 performs the selective addition control operation of the addition circuit 15 in accordance with the input recording signal, and the signal subjected to the selective addition control is supplied to the laser driving circuit 2. As a result, a drive signal having a waveform shown in FIG. 2 from the laser drive circuit 2, that is, a pulse waveform consisting of a peak level value P and a bottom level value B, is supplied to the laser diode 1 during the recording period R, and the erase level value B 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 generation operation of the laser drive pulse signal 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 photodetector amplification circuit 5 and the RF. The RF signal level in the erasing period S is made constant by the amplifying operation by the signal amplifying circuit 7, the sampling operation by the erasing period sampling circuit 9, the detecting operation of the erasing period signal by the signal level detecting circuit 10, and the servo operation by the servo circuit 14. Controlled. 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 value of the erasure level E is controlled by using the level of the signal obtained during the erasure period among the signals reflected from the disk 4, but the photodetector 3 that receives the reflected light from the disk 4. Since the gain of the photodetector amplifying circuit 5 for amplifying the signal obtained from the above is set based on the reflectivity of the disk 4, the control operation of the erasure level value E optimum for the characteristics of the disk 4 is accurately performed. I can do it.

As described above, the control operation of the erase level value E is performed, but the operation of controlling the peak level value P and the bottom level value B according to the change of the erase level value E with the erase level value E as a reference. Will be done. The adjustment operation of the peak level value P and the bottom level value B is performed based on the ε value set according to the characteristics of the disk 4. Therefore, when the erase level value E is changed to keep the RF signal level constant, the peak level value P and the bottom level value B are changed in accordance with the change, so that a recording operation suitable for the state is performed. I can do it.

  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 laser output for performing the reproduction operation set in advance is set to the level adjusted during the recording operation described above. If the laser output for this is changed, a laser output suitable for performing the reproducing operation can be obtained.

  In this embodiment, the gain of the photodetector amplifier circuit 5 is controlled based on the reflectance data of the disk 4, but the gain of the RF signal amplifier circuit 7 can also be controlled.

1 is a circuit diagram showing an embodiment of an optical disc recording / reproducing apparatus according to the present invention. It is a wave form diagram of a signal which drives a laser diode concerning the present invention.

Explanation of symbols

1 Laser diode
2 Laser drive circuit
3 Photodetector
5 Photodetector amplification circuit
6 Gain control circuit
8 Control circuit
DESCRIPTION OF SYMBOLS 9 Erase period sampling circuit 10 Signal level detection circuit 11 Peak level signal output circuit 12 Bottom level signal output circuit 13 Erase level signal output circuit 14 Servo circuit 15 Adder circuit 16 Memory circuit

Claims (4)

In an optical disk recording / reproducing apparatus configured to record a signal on a disk by driving a laser diode incorporated in an optical pickup with a pulse 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, an amplification circuit for a photodetector that amplifies a signal obtained from the photodetector, and amplification for the photodetector An erasing period sampling circuit that samples a signal of an erasing period among signals output from the circuit, a signal level detection circuit that detects a level of a signal obtained from the erasing period sampling circuit, and a pulse signal supplied to the laser diode Set the erase level value, peak level value, and bottom level value And a control circuit that controls the operation of the memory circuit that stores the reflectance data corresponding to the characteristics of the disc, and detects the disc type when the disc is loaded and the reflectivity according to the detected type. The gain of the photodetector amplifier circuit is set based on the data, and the servo operation is performed on the circuit that outputs the erase level signal so as to make the signal level detected by the signal level detection circuit constant. A method for controlling a laser drive signal of an optical disc 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. 2. The laser drive signal control method according to claim 1, wherein the disc type is detected by disc information data recorded on the disc.

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