JP2005071473A - 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 a reproducing period sampling circuit 7 sampling an RF signal of a reproducing period in an 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 a reproducing 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.

  Among such optical disc recording / reproducing apparatuses, there is a so-called write-once type in which a signal recording operation to the disc can be performed only once, and a CD-R type recording / reproducing using a CD type recording disc. The device is widespread. In such a recordable optical disk recording / reproducing apparatus, a laser diode incorporated in an optical pickup is driven to light by a pulse signal composed of a recording level value VR and a reproducing level value VP shown in FIG. Is recorded on the disc.

In an optical disk recording / reproducing apparatus that records a signal on a disk by driving a laser diode to light with such a pulse signal, the recording level value VR and the reproduction level value VP are accurately controlled to perform a high-quality recording operation on the disk. The technique which performs is developed (for example, refer patent document 1).
JP 2002-230768 A

  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 in the optical pickup, 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. Recently, in order to solve such a problem, an optical disk recording / reproducing apparatus which performs a recording / reproducing operation using an optical pickup from which a monitoring diode is removed has been commercialized.

  When using an optical pickup that does not have a monitoring diode, the level control operation of the laser drive signal is performed using the level change of the laser light reflected from the disk, but it is reflected from the disk. The level of the laser beam is affected by the characteristics of the disk and the laser output characteristics change due to the temperature of the laser diode, so that 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 amplification circuit, reproduction period sampling circuit for sampling the RF signal in the reproduction period in the RF signal output from the RF signal amplification 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 a recording level value and a reproduction level value of a pulse signal supplied to the laser diode, a temperature detection circuit for detecting the temperature of the optical pickup, and a correction value in which a correction value for the temperature is stored It consists of a memory circuit and the playback level to make the signal level detected by the signal level detection circuit constant. It is configured to perform level correction operation for the circuit which outputs a reproduction level signal based on the correction value corresponding to the temperature performs servo operation for the circuit for outputting a degree.

  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 reproduction level controlled to control the laser output in accordance with the temperature is corrected. Can be performed accurately.

  In the present invention, since the recording level value is set based on the reproduction level value that is controlled to control the laser output, it is possible to generate a laser drive signal for accurately performing the recording operation. I can do it.

  The present invention reproduces 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. 2A shows the waveform of the laser drive signal supplied to the laser diode 1, and during the recording period in which the signal recording operation is performed, the drive signal having the recording level value VR is supplied to perform the recording operation. During the non-reproduction period, a drive signal having a reproduction level value VP is supplied.

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 a reproduction period sampling circuit whose operation is controlled by the control circuit 6. Is input, and the RF signal during the reproduction period is sampled and output. Reference numeral 8 denotes a signal level detection circuit that receives the signal sampled by the reproduction period sampling circuit 7 and detects the level of the signal, and is configured to output a detection signal to the control circuit 6.

  Reference numeral 9 denotes a recording level signal output circuit whose operation is controlled by the control circuit 6, which is set to output a signal for causing the laser driving circuit 2 to output a signal of a recording level value VR for recording a signal on the disc. . A reproduction level signal output circuit 10 whose operation is controlled by the control circuit 6 is set to output a signal for causing the laser driving circuit 2 to output a signal of the reproduction level value VP.

  A servo circuit 11 performs a servo operation on the reproduction level signal output circuit 10 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 reproduction period constant.

  Reference numeral 12 denotes an adder circuit to which the output signals of the recording level signal output circuit 9 and the reproduction level signal output circuit 10 are input, and performs a selective addition operation of signals input by the control operation by the control circuit 6, and the selective addition thereof The generated signal is supplied to the laser driving circuit 2.

  Reference numeral 13 denotes a temperature detection circuit incorporating a temperature detection element (not shown), which is connected so as to detect the temperature of the optical pickup and to output the detected output to the control circuit 6. A correction value memory circuit 14 stores a correction value for the reproduction signal output circuit 10 with respect to the temperature detected by the temperature detection circuit 13. The correction value stored in the correction value memory circuit 14 is set to a value for correcting the change because the output characteristics of the laser diode 1 change 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. 2A shows the pulse waveform of the drive current supplied to the laser diode 1, and FIG. 2B shows the output signal of the RF amplifier circuit 5 that amplifies the RF signal obtained from the photodetector 3. FIG. Yes, the waveform is shaped according to the signal level. As is apparent from the figure, the level of the RF signal obtained corresponding to the recording level value VR has the highest level at the rising portion and then gradually decreases. 2C is a sampling pulse output from the control circuit 6 to the reproduction period sampling circuit 7. The RF signal during the period when the drive signal of the reproduction level value VP is supplied to the laser diode 1 is shown. It is comprised so that it may be output at the timing which extracts.

  In the state where the signal recording operation to the disk 4 is being performed, the RF signal during the reproduction period is sampled by the reproduction period sampling circuit 7, so that the level of the RF signal during the reproduction period is monitored. A monitor signal, which is an RF signal sampled by the reproduction period sampling circuit 7, is input to the signal level detection circuit 8, and the level is detected, and then input to the control circuit 6. When such a monitor signal is input to the control circuit 6, the control circuit 6 controls the reproduction level so as to make the level of the signal detected by the signal level detection circuit 8 constant by the servo operation by the servo circuit 11. The level of the signal output from the signal output circuit 10, that is, the reproduction level value VP is controlled.

In addition, the temperature detection operation of the optical pickup is performed by the temperature detection circuit 13, and a correction value corresponding to the detected temperature is read from the correction value memory circuit 14, and the reproduction level signal output circuit is read based on the read correction value. The level value output from 10 is corrected.

  As described above, the optical disk recording / reproducing apparatus according to the present invention is configured. Next, the operation will be described. In an optical disc recording / reproducing apparatus, a test signal is recorded while changing the laser output in a stepwise manner in a test writing area provided on the inner circumference side of the disc, and the reproduction quality of the recorded test signal is measured. It is configured to set a suitable laser output. The laser output set by such setting operation is set not only for the recording level value VR and the reproduction level value VP but also the relationship between the recording level value VR and the reproduction level value VP according to the recording characteristics of the disc 4. Will be.

  When such a setting operation is performed, signals of the recording level value VR and the reproduction level value VP are output from the laser driving circuit 2 from the recording level signal output circuit 9 and the reproduction level signal output circuit 10, respectively, by the control operation of the control circuit 6. A control operation is performed.

  The control circuit 6 performs the selective addition control operation of the adder circuit 12 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, a drive signal having a waveform shown in FIG. 2A, that is, a pulse waveform composed of the recording level value VR and the reproduction level value VP is supplied from the laser driving circuit 2 to the laser diode 1. The period in which the recording level value VR in which the laser drive signal having such a pulse waveform is output and the period in which the reproduction level VP 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 reproduction level value VP is determined by the reflected signal detection operation by the photodetector 3, the amplification operation by the RF signal amplification circuit 5, The level of the RF signal during the reproduction period is controlled to be constant by the sampling operation by the reproduction period sampling circuit 7, the level detection operation of the reproduction period signal by the signal level detection circuit 8, and the servo operation by the servo circuit 11. Accordingly, an operation for controlling the reproduction level value VP is performed so that a desired laser output can be obtained even if the level of the laser beam 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 11 is performed. When such an operation is performed, the temperature detection operation of the optical pickup by the temperature detection circuit 13 is performed. Then, a correction value corresponding to the temperature detected by the temperature detection circuit 13 is read from the correction value memory circuit 14, and an operation for correcting the output level of the reproduction level signal output circuit 10 based on the correction value is performed. Is called. Such an output level correction operation or the like can be performed by digital signal processing by the control circuit 6.

  As described above, the control operation of the playback level value VP is performed, but the operation of controlling the value of the recording level value VR according to the change of the playback level value VP is performed using the playback level value VP as a reference. . Then, the adjustment operation of the recording level value VR is performed based on the relationship set by the adjustment operation of the laser output. Accordingly, when the reproduction level value VP is changed to keep the RF signal level constant, the recording level value VR is changed in accordance with the change, so that a recording operation suitable for the state can be performed.

As described above, the control operation of the laser drive signal in the recording operation state is performed, but 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 The level value set for performing the reproduction operation is controlled so that the laser output for performing the reproduction operation set in advance is adjusted in the recording operation described above. If the laser output for reproduction is changed in accordance with the level change, a laser output suitable for performing the reproduction operation can be obtained.

  In the present embodiment, the signals output from the recording level signal output circuit 9 and the reproduction level signal output circuit 10 are added and controlled by the adder circuit 12, so that the drive signal is supplied to the laser drive circuit 2. The signals output from the recording level signal output circuit 9 and the reproduction level signal output circuit 10 can be selectively switched and supplied to the laser driving circuit 2.

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 Reproduction period sampling circuit
8 Signal level detection circuit
9 Recording level signal output circuit 10 Playback level signal output circuit 11 Servo circuit 12 Adder circuit 13 Temperature detection circuit 14 Correction value memory circuit

Claims (2)

An optical disk recording / reproducing apparatus configured to record a signal on a disk by driving a laser diode incorporated in the optical pickup with a pulse signal composed of a recording level value and a reproduction level value. A photodetector that converts laser light that is incorporated and reflected from the disk into an electrical signal, an RF signal amplification circuit that receives an RF signal obtained from the photodetector and amplifies the signal, and the RF A reproduction period sampling circuit that samples an RF signal in the reproduction period in the RF signal output from the signal amplification circuit, a signal level detection circuit that detects the level of the RF signal obtained from the sampling circuit, and a laser diode System to set the recording level value and playback level value of the pulse signal. It consists of a circuit, 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 reproduces the signal level detected by the signal level detection circuit to be constant. A laser of an optical disk recording / reproducing apparatus characterized in that a servo operation is performed on a circuit that outputs a level signal and a level correction operation is performed on a circuit that outputs a reproduction level signal based on a correction value corresponding to temperature. Drive signal control method. 2. The laser drive signal control method according to claim 1, wherein the recording level value is set based on the reproduction level value.

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