JP2005135542A - Optical disk recording and reproducing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical disk recording and reproducing device which allows a signal to be recorded on a disk, by a laser light radiated from an optical pickup. <P>SOLUTION: By applying a pulse signal having a pulse width set in the range between a minimum pulse width and a maximum pulse width to a laser diode 5 incorporated in the optical pickup 4 as a driving signal, this optical disk recording and reproducing device is constituted so as to record the signal on the disk 1. When a reproduced pulse width of a signal recorded on the disk 1 is detected based on a reflected light obtained from a disk surface, and the pulse width of a minimum pulse deviates by more than a setting length with respect to a specified value, the pulse width of the minimum pulse applied to the laser diode 5 is varied and adjusted. <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.

Such an optical disc recording / reproducing apparatus is configured to form pits on the disc by laser light. However, if the laser output value is not optimal, the shape of the pits may be too large or too small. become. For this reason, such an optical disc recording / reproducing apparatus is configured to accurately perform the signal recording operation on the disc by controlling the level of the drive signal supplied to the laser diode (see, for example, Patent Document 1). ).
JP 2001-23173 A

  A disc called a write-once type is configured to perform signal recording operation by forming pits by irradiating a signal surface with laser light. Then, a laser signal necessary for the recording operation is irradiated by supplying a driving signal having a pulse width corresponding to the recording signal to the laser diode that irradiates the laser beam.

  The width of the pulse signal supplied to the laser diode is 3T to 11T or 3T to 14T (T is one period of the recording channel clock) according to the disc standard. The recording operation of the signal to the disk is performed by supplying the diode.

  FIG. 2 shows the relationship between a recording signal and a recording pulse signal. FIG. 2A shows a pulse signal generated corresponding to the recording signal, and FIG. A drive pulse signal having a single pulse shape corresponding to the recording signal. In the recording operation using a single pulse shape signal, the shape of the pit recorded by heat storage is distorted in a tear shape, so that correction such as increasing the laser output at the head portion of the recording pulse is performed as shown in the figure. .

  Further, in an optical disk recording / reproducing apparatus, in order to perform a signal recording operation on the disk in a short time, the recording operation is performed in a state where the rotational speed of the disk is set to a high speed such as 4 times or 8 times the specified speed. Has been. In order to perform the recording operation with the disc rotated at a high speed, it is necessary to increase the level of the laser output and to accurately perform the automatic level control operation of the laser output.

  When the recording operation is performed with a high laser output, there is a problem that the disk causes thermal interference and the recording quality deteriorates. Especially, the 3T signal having the minimum pulse width is greatly affected, and the signal recording operation is performed accurately. There is a problem that it cannot be done.

  The present invention is intended to provide an optical disc recording / reproducing apparatus that can solve such a problem.

  The present invention records a signal on a disk by supplying a pulse signal having a pulse width set between the minimum pulse width and the maximum pulse width to a laser diode incorporated in an optical pickup as a drive signal. In the optical disc recording / reproducing apparatus configured as described above, when the signal is recorded on the disc, the reproduction pulse width of the recorded signal is detected based on the reflected light obtained from the disc surface, and the pulse width of the minimum pulse is set to the specified value. On the other hand, the pulse width of the minimum pulse supplied to the laser diode is variably adjusted when the length differs by more than a set length.

  Further, the present invention adjusts the level of the drive signal supplied to the laser diode based on the signal obtained from the monitoring diode incorporated in the optical pickup so as to monitor the output of the laser beam output from the laser diode. An automatic level adjustment circuit is provided, and the pulse width of the minimum pulse is variably adjusted based on the level of the drive signal to the laser diode accompanying the automatic adjustment operation of the automatic adjustment circuit.

  And this invention is comprised so that the adjustment amount with respect to the minimum pulse width supplied to a laser diode may be changed according to the difference amount of the pulse width of a minimum pulse and a regulation value.

  The present invention records a signal on a disk by supplying a pulse signal having a pulse width set between the minimum pulse width and the maximum pulse width to a laser diode incorporated in an optical pickup as a drive signal. In the optical disc recording / reproducing apparatus configured as described above, when the signal is recorded on the disc, the reproduction pulse width of the recorded signal is detected based on the reflected light obtained from the disc surface, and the pulse width of the minimum pulse is set to the specified value. On the other hand, when the difference is more than the set length, the pulse width of the minimum pulse supplied to the laser diode is variably adjusted, so even if it is affected by thermal interference, the effect can be corrected, so accurate recording The operation can be performed.

  Further, the present invention adjusts the level of the drive signal supplied to the laser diode based on the signal obtained from the monitoring diode incorporated in the optical pickup so as to monitor the output of the laser beam output from the laser diode. Since the automatic level adjustment circuit is provided and the pulse width of the minimum pulse is variably adjusted based on the level of the drive signal to the laser diode accompanying the automatic adjustment operation of the automatic adjustment circuit, more accurate recording operation is performed. I can do it.

  In the present invention, the adjustment amount for the minimum pulse width supplied to the laser diode is changed according to the difference between the pulse width of the minimum pulse and the specified value, so that the signal of the minimum pulse width is accurately recorded. I can do it.

  In the present invention, the width of the reproduction pulse is detected from the reflected light obtained from the disk surface during the recording operation, and the pulse width is controlled based on the detection result.

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 of a pulse signal. In FIG. 1, reference numeral 1 denotes a disk that is mounted on a turntable 3 that is rotationally driven by a spindle motor 2 and is rotationally driven. A groove called a pregroove is formed in a meandering manner on the recording disk.

  Reference numeral 4 denotes a laser diode 5 for irradiating the disk 1 with laser light, a monitoring diode 6 for monitoring the output of the laser light emitted from the laser diode 5, and a photodetector for receiving laser light reflected from the signal surface of the disk 1. 7 is an optical pickup incorporating a focusing coil (not shown) and a laser for focusing laser light on the signal surface by displacing an objective lens (not shown) in the direction of the signal surface of the disk 1. A tracking coil (not shown) for displacing the objective lens in the track direction in order to make the light follow the signal track is incorporated, and can be moved in the radial direction of the disk 1 by a pickup feed motor (not shown). It is configured.

  Reference numeral 8 denotes an RF signal amplifying circuit for amplifying the RF (high frequency) signal obtained from the photodetector 7 and a signal amplified by the RF signal amplifying circuit 8. The circuit is configured to shape the waveform of an input signal and output a binarized signal. Reference numeral 10 denotes a digital signal processing circuit to which a signal binarized by the binarizing circuit 9 is input, and is configured to perform demodulation operations of various signals.

  11 receives a signal demodulated by the digital signal processing circuit 10 and performs various control operations in response to a command signal output from a host device (not shown), and transmits signals to and from the host device. It is a system control circuit that controls input / output operations. Reference numeral 12 denotes a signal recording circuit whose operation is controlled by the system control circuit 11 and which performs an encoding process operation of a recording signal.

  Reference numeral 13 denotes a laser diode driving circuit to which a pulse signal corresponding to the recording signal output from the signal recording circuit 12, for example, a pulse signal having a pulse width of 3T to 11T is input, and the driving signal corresponding to the pulse width is The laser diode 5 incorporated in the optical pickup 4 is supplied. Reference numeral 14 denotes a laser output control circuit whose operation is controlled by the system control circuit 11, and provides a recording drive signal at a level corresponding to the rotational speed of the disk 1 and a reproduction drive signal at a level suitable for performing a reproduction operation. The laser diode drive circuit 13 is configured to output. 15 adjusts the level of the drive signal supplied from the laser diode drive circuit 13 based on the monitor signal obtained from the monitor diode 6 provided to monitor the output level of the laser light emitted from the laser diode 5. This is a laser output automatic adjustment circuit.

  Reference numeral 16 denotes a pulse width detection circuit for detecting the pulse width of the pulse signal output from the binarization circuit 9, which detects the minimum width pulse used for the recording operation, that is, the pulse width of the 3T pulse, and detects it. A signal is output to the system control circuit 11. Reference numeral 17 denotes a pulse width adjusting circuit whose operation is controlled by the system control circuit 11, and a signal recording circuit when the 3T pulse width detected by the pulse width detecting circuit 16 is different from a predetermined value by a set value or more. The pulse width of the 3T pulse in the pulse signal output from 12 is adjusted. Further, the level of the laser output obtained from the laser output automatic adjustment circuit 15 is detected, and when the level reaches a predetermined level, that is, a level affected by thermal interference, an adjustment operation by the pulse width adjustment circuit 17 is performed. It is configured.

  A spindle motor drive circuit 18 controls the spindle motor 2 to rotate and is configured to rotate the disk 1 at a predetermined recording speed by the control operation of the system control circuit 11.

Although the present invention is configured as described above, the operation will be described next. When a command signal for performing a recording operation is output from the host device, the control operation for the recording operation by the system control circuit 11 is started. In such a recording operation, first, a test signal is recorded in a test writing area provided on the inner peripheral side of the disk 1 while changing the laser output, and the recorded signal is reproduced to reproduce a laser suitable for the recording operation. It starts from the output setting operation. Such a laser output setting operation may be performed by using a well-known technique, and a description thereof will be omitted.

  When the setting operation of the laser output is completed, a control operation for starting the recording operation of the data signal output from the host device is performed. The disk 1 is rotationally driven at a desired rotational speed by the rotational driving operation of the spindle motor 2 by the spindle motor driving circuit 18. Such a rotational drive operation is performed, for example, so that the linear velocity is constant. Such a control operation is performed by using a wobble signal obtained from a pregroove formed on the disk 1.

  Further, the level setting operation of the drive signal supplied from the laser diode drive circuit 13 to the laser diode 5 is performed by the control operation for the laser output control circuit 14 by the system control circuit 11. The laser output level set in this way is the level set by the laser output setting operation using the test writing area.

  In such a state, the recording operation is started by moving the optical pickup 4 to a position for starting the recording operation. The search operation for the recording start position is performed by using the digital signal processing circuit to obtain the position information data obtained from the wobble signal. This is done by extracting at 10. Such a search operation can be performed by a known technique.

  When the optical pickup 4 moves to the recording start position, the recording signal transmitted from the host device and stored in the buffer memory (not shown) is input to the signal recording circuit 12. The recording signal input to the signal recording circuit 12 is encoded and then converted into a pulse signal corresponding to the recording signal, that is, a pulse signal composed of 3T to 11T, and applied to the laser diode driving circuit 13. Such a pulse signal is as shown in FIG.

  When a pulsed signal corresponding to the recording signal is applied to the laser diode driving circuit 13 in this way, a driving signal corresponding to the width of the pulse signal is sent from the laser diode driving circuit 13 to the laser diode 5. Is output. Such a drive signal is as shown in FIG. 2B, and is corrected so that the laser output at the head portion of the recording pulse is increased.

  When the pulse signal shown in FIG. 2B is supplied to the laser diode 5, the laser light emitted from the laser diode 5 is applied to the signal surface on the disk 1, and pits are formed on the signal surface of the disk 1. Then, a signal recording operation is performed. With this operation, the recording operation of the recording signal onto the disk 1 is started, but the monitor signal obtained from the monitoring diode 6 is in the state of being input to the laser output automatic adjustment circuit 15 in the recording state. As a result, since the laser output level automatic adjustment operation for the laser diode drive circuit 13 by the laser output automatic adjustment circuit 15 is performed, the drive signal level supplied to the laser diode 5 is held at a value suitable for the recording operation. I can do it.

The recording signal is recorded on the disk 1 by the above-described operation. When such a recording operation is performed, the laser reflected from the disk 1 by the photodetector 7 incorporated in the optical pickup 4. A light detection operation is performed. The signal obtained from the photodetector 7 is input to the RF signal amplifier circuit 8 and amplified and then input to the binarization circuit 9. The signal input to the binarization circuit 9 is binarized and output to the digital signal processing circuit 10. The pulse width of the binarized pulse signal is detected by the pulse width detection circuit 16. Will be.

  The pulse width detection operation by the pulse width detection circuit 16 is performed on a 3T pulse signal which is a minimum pulse width signal. The pulse width detected by the pulse width detection circuit 16 is input to the system control circuit 11. The system control circuit 11 compares the input 3T pulse width with a specified 3T pulse width stored in a memory circuit (not shown). When the influence of thermal interference on the disk 1 is small, the difference between the pulse width detected by the pulse width detection circuit 16 and the specified pulse width is small, so that the adjustment operation by the pulse width adjustment circuit 17 is not performed.

  As the laser output increases, the influence of thermal interference on the disk increases, and the pulse width of the 3T pulse signal detected by the pulse width detection circuit 16 changes. When the detected pulse width of the 3T pulse signal changes and the difference from the specified pulse width exceeds a predetermined length, the pulse width of the 3T pulse signal output from the signal recording circuit 12 is changed corresponding to the difference length. A control operation for this purpose is performed by the pulse width adjustment circuit 17.

  FIG. 2C shows the waveform of the drive pulse output from the laser diode drive circuit 13 in response to the recording pulse subjected to such pulse width adjustment and change operation, and corresponds to the 3T pulse signal. The width of the drive pulse to be narrowed. When the drive pulse signal adjusted in this way is supplied to the laser diode 5, the shape of the pit recorded on the disk 1 is reduced, that is, the shape of the pit that has been enlarged due to thermal interference can be reduced. As a result, the laser output irradiated from the laser diode 5 is increased, and it is possible to prevent the shape of the pit recorded on the signal surface of the disk 1 from being outside the specified value due to thermal interference.

  As described above, when the pulse width of the 3T pulse signal detected by the pulse width detection circuit 16 is different from the specified value by a predetermined length or more, the pulse width adjustment circuit 17 performs the variable adjustment operation of the pulse width. It is also possible to control based on the laser output detected by the laser output automatic adjustment circuit 15. That is, it is determined whether or not the laser output detected by the laser output automatic adjustment circuit 15 has reached a level affected by the thermal interference in the recording operation of the disk 1, and the level has reached the level affected. At this time, it is also possible to perform a pulse width change adjustment operation accompanying the detection operation of the pulse width detection circuit 16.

  According to such a configuration, it can be recognized that the reason why the pulse width of the 3T pulse signal detected by the pulse width detection circuit 16 is different from the specified pulse width is that the laser output level is high. The variable width adjustment operation can be performed accurately.

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 of a pulse signal concerning the present invention.

Explanation of symbols

1 disc
2 Spindle motor
4 Optical pickup
5 Laser diode
6 Diode for monitoring
7 Photodetector
9 Binarization circuit 10 Digital signal processing circuit 11 System control circuit 12 Signal recording circuit 13 Laser diode drive circuit 14 Laser output control circuit 15 Laser output automatic adjustment circuit 16 Pulse width detection circuit 17 Pulse width adjustment circuit

Claims (3)

It is configured to record a signal on a disk by supplying a pulse signal having a pulse width set between the minimum pulse width and the maximum pulse width as a drive signal to a laser diode incorporated in the optical pickup. In an optical disc recording / reproducing device, when a signal is recorded on the disc, the reproduction pulse width of the signal recorded based on the reflected light obtained from the disc surface is detected, and the pulse width of the minimum pulse is a set length with respect to the specified value. An optical disc recording / reproducing apparatus characterized by variably adjusting the pulse width of the minimum pulse supplied to the laser diode when different from the above. An automatic level adjustment circuit that adjusts the level of the drive signal supplied to the laser diode based on the signal obtained from the monitoring diode built into the optical pickup to monitor the output of the laser light output from the laser diode 2. The optical disc recording / reproducing apparatus according to claim 1, wherein the pulse width of the minimum pulse is variably adjusted based on the level of the drive signal to the laser diode accompanying the automatic adjustment operation of the automatic adjustment circuit. . 2. The optical disc recording / reproducing apparatus according to claim 1, wherein the adjustment amount for the minimum pulse width supplied to the laser diode is changed according to the difference between the pulse width of the minimum pulse and the specified value.

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