JP2005158206A - Tilt control method of optical disk recording or reproducing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tilt control method of an optical disk recording or reproducing apparatus which can record a signal on a disk with an optical pickup. <P>SOLUTION: While changing a level of a drive signal for offset sensing to be supplied to a coil for conditioning a tilt in a test writing area and a signal recording area set up in an inner periphery side of a disk, the optical disk recording or reproducing apparatus records signals for offset conditioning and then performs reproducing operation of the signals for offset conditioning recorded; detects βvalues from RF signals reproduced; sets levels of the drive signals supplied to the coil for tilt conditioning as an inner periphery side offset value and a periphery side offset value, when signals with which the βvalues detected serve as maximum are recorded; and performs tilt control by adding an offset value according to a record position calculated from the inner periphery side offset value and the periphery side offset value to a tilt conditioning signal which performs tilt control. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a tilt control method for an optical disc recording / reproducing apparatus configured to record a signal on a disc by a laser beam irradiated from an optical pickup and perform a reproducing operation of the signal recorded on the disc by the laser beam. .

  Disc players that use an optical pickup to read signals recorded on a disc are widely used. In addition to the playback function, a signal can be recorded on the disc by a laser beam emitted from the optical pickup. An optical disc recording / reproducing apparatus configured so as to be able to be made has been commercialized.

  In the optical disc recording / reproducing apparatus, since it is necessary to accurately irradiate the signal track of the disc with the laser beam emitted from the optical pickup, the focus control operation and the tracking control operation are performed. Such a focus control operation is performed by supplying a drive current to a focusing coil that displaces the objective lens in the disk surface direction, and a tracking control operation is performed by applying a drive current to the tracking coil that displaces the objective lens in the radial direction of the disk. This is done by supplying.

  Recently, the recording density has been increased in order to record many signals on the disk. In order to perform a high-density recording operation, it is necessary to irradiate the disk surface with laser light in an optimum state. In order to perform such an operation, not only the above-described focus control operation and tracking control operation are accurately performed, but also an operation for correcting a relative angular deviation between the disc and the objective lens, that is, a tilt control operation is performed. An optical pickup configured to be able to be developed has been developed (for example, see Patent Document 1).

  A technique for detecting the inclination of the optical pickup with respect to the disk and adjusting the inclination has been developed (see, for example, Patent Document 2).

  In addition, when recording a signal on the disc, it is necessary to set the laser beam output to a level suitable for the recording characteristics of the disc, so a test signal is applied to the test writing area provided on the inner circumference side of the disc. There is a technique for adjusting the laser output by recording while changing the laser output and reproducing the recorded signal (see, for example, Patent Document 3).

Some optical disc recording / reproducing apparatuses use a rewritable disc that can perform a recording / erasing operation not only once but also a recording / erasing operation.
JP 2002-197698 A JP 2001-52362 A JP-A-8-45099

The technology described in Patent Document 2 is configured to provide a tilt sensor that detects the tilt of the optical pickup with respect to the disk, and to perform a tilt adjustment operation based on a signal obtained from the tilt sensor. According to such a technique, although an accurate tilt adjustment control operation can be performed, the tilt sensor is expensive, and there is a problem that the optical disc recording / reproducing apparatus is expensive.

  In addition, the tilt adjustment coil incorporated in the optical pickup is fixed to a support member that supports the objective lens. Since there is a change over time, the tilt angle is not constant when the drive voltage is not supplied to the tilt adjustment coil. Therefore, there is a problem that accurate tilt adjustment is not performed when the tilt adjustment operation is performed in such a state.

  The present invention is intended to provide a tilt control method for an optical disc recording / reproducing apparatus capable of solving such a problem.

  The present invention records the offset adjustment after recording the offset adjustment signal while changing the level of the drive signal for offset detection supplied to the tilt adjustment coil in the test writing area provided on the inner circumference side of the disc. Signal is reproduced, the β value is detected from the reproduced RF signal, and the level of the drive signal supplied to the tilt adjustment coil is recorded when the signal with the maximum detected β value is recorded. The offset recorded after the offset adjustment signal was recorded while changing the level of the drive signal for offset detection supplied to the tilt adjustment coil in the signal recording area provided on the disc and set as the circumferential offset value When the adjustment signal is reproduced, the β value is detected from the reproduced RF signal, and the signal with the maximum detected β value is recorded. The level of the drive signal supplied to the adjustment coil is set as the outer offset value, and the tilt adjustment signal for tilt control is offset according to the recording position calculated from the inner offset value and the outer offset value. Tilt control is performed by adding the values.

  The present invention records the offset adjustment after recording the offset adjustment signal while changing the level of the drive signal for offset detection supplied to the tilt adjustment coil in the test writing area provided on the inner circumference side of the disc. Signal is reproduced, the β value is detected from the reproduced RF signal, and the level of the drive signal supplied to the tilt adjustment coil is recorded when the signal with the maximum detected β value is recorded. The offset recorded after the offset adjustment signal was recorded while changing the level of the drive signal for offset detection supplied to the tilt adjustment coil in the signal recording area provided on the disc and set as the circumferential offset value When the adjustment signal is reproduced, the β value is detected from the reproduced RF signal, and the signal with the maximum detected β value is recorded. The level of the drive signal supplied to the adjustment coil is set as the outer offset value, and the tilt adjustment signal for tilt control is offset according to the recording position calculated from the inner offset value and the outer offset value. Since the tilt control is performed by adding the values, accurate tilt adjustment can be performed without being affected by the displacement of the attachment position of the tilt adjustment coil, the temperature change, and the change with time.

  In particular, the present invention uses the offset values set on the inner and outer peripheral sides of the disc to calculate and set the offset value according to the recording position, so that it is suitable for the disc. Adjustment operation can be performed accurately.

  The present invention has the advantage that the offset value in all signal recording areas can be calculated and set because the setting operation of the outer peripheral offset value is performed at the outermost peripheral position in the signal recording area. doing.

  The present invention records the offset adjustment signal in the test writing area provided on the inner peripheral side of the disc and the outer peripheral side of the disc while changing the angle of the optical pickup with respect to the disc, thereby offset values at each position. Is to be selected.

  FIG. 1 is a circuit diagram showing an embodiment of an optical disk recording / reproducing apparatus according to the present invention, FIGS. 2 and 3 are signal waveform diagrams for explaining the operation of the present invention, and FIG. 4 is a plan view showing a disk according to the present invention. FIG.

  In FIG. 1, reference numeral 1 denotes a disk placed on a turntable (not shown) that is rotationally driven by a spindle motor (not shown). When adjusting the laser output from the inner periphery as shown in FIG. A test writing area A, a PMA area B indicating the recording contents of the disc, and a signal recording area C are provided. The test writing area A is an area used when the recording laser output is adjusted before performing the recording operation of the data signal in the signal recording area C. A method for adjusting the laser output using such an area is as follows. Since it is well known, its description is omitted.

  Further, position information data indicating the position on the disk is recorded on the disk 1 by meandering grooves called pregrooves, and the optical disk recording / reproducing apparatus records signals based on the wobble signal obtained from the grooves. It is configured to perform a reproduction operation and a signal recording position recognition operation. Reference numeral 2 denotes a laser diode 3 that emits laser light emitted to the disk 1 and a monitor diode (not shown) that monitors the amount of laser light emitted from the laser diode 3. An optical pickup incorporating a photodetector 4 that receives laser light reflected from the signal surface, and is configured to be moved in the radial direction of the disk 1 by a pickup feed motor (not shown). .

  Further, in the optical pickup 2, a focusing coil 5 for displacing an objective lens (not shown) in the surface direction of the disc 1, a tracking coil 6 for displacing the objective lens in the radial direction of the disc 1, and a disc of the objective lens. A tilt adjusting coil 7 for adjusting an angle with respect to 1 is incorporated.

  Reference numeral 8 denotes a focusing control operation for focusing the laser light emitted from the laser diode on the signal surface of the disk 1 based on the signal obtained from the photodetector 4 incorporated in the optical pickup 2, and the laser light as a signal. A pickup control circuit that performs a tracking control operation to follow a signal track on a surface, and is configured to output a tracking control signal based on a tracking error signal and a focusing control signal based on a focus error signal.

  Reference numeral 9 denotes a tracking coil driving circuit to which a tracking control signal output from the pickup control circuit 8 is input, and is configured to supply a driving signal to the tracking coil 6 incorporated in the optical pickup 2. . Reference numeral 10 denotes a focusing coil driving circuit to which a focusing control signal output from the pickup control circuit 8 is input, and is configured to supply a driving signal to the focusing coil 5 incorporated in the optical pickup 2. .

Reference numeral 11 denotes an RF signal amplification circuit for amplifying the RF signal obtained from the photodetector 4 incorporated in the optical pickup 2 and reference numeral 12 denotes a signal output from the RF signal amplification circuit 11. This is a β value detection circuit for detecting a β value. FIG. 2 is a waveform diagram of a signal obtained by reproducing a signal recorded on the disc 1, and A1 and A2 are a positive peak level and a negative peak level of the high-frequency signal.

  Under such conditions, the β value is expressed as β = (A1 + A2) / (A1−A2). When this β value is, for example, 0.04, the signal is recorded with the optimum laser output. ing. On the other hand, the relationship between the inclination of the objective lens with respect to the signal surface of the disk 1, that is, the tilt state and the β value, has a characteristic that the β value increases as the tilt adjustment becomes better.

  Next, such characteristics will be described. In FIG. 2, P indicates pits formed by irradiating the disk 1 with laser light, and shows the relationship with the reproduction waveform. FIG. 3 shows a state in which the tilt adjustment is better than the state shown in FIG. 2, and the shape of the pit P formed when recording is performed with the same laser output, the laser beam is more efficient. Since the signal surface is irradiated, it becomes large. As apparent from the reproduction waveform diagram of FIG. 3, when the shape of the pit P is increased, the positive peak level of the high frequency signal to be reproduced is increased and the negative peak level is decreased. Thus, it can be seen that when the tilt adjustment is in a good state, the values of A1 and A2 change, and therefore the β value increases.

  Reference numeral 13 denotes a tilt for performing a tilt control operation based on a tilt adjustment signal obtained from a drive signal output from the focusing coil drive circuit 10 while a β value detected and output by the β value detection circuit 12 is input. A control circuit 14 is a tilt coil drive circuit whose operation is controlled by a signal output from the tilt control circuit 13. The tilt adjustment coil 7 incorporated in the optical pickup 2 is driven for tilt adjustment. It is configured to provide a signal.

  Reference numeral 15 denotes an offset detection circuit that enters an operation state during an offset value detection operation performed before the recording operation. The tilt control circuit 13 tilts the tilt coil drive circuit 14 stepwise, that is, the objective lens with respect to the disk 1 is moved. A signal for causing the tilt adjustment coil 7 to output a drive signal for offset detection for changing the tilt is output. Reference numeral 16 denotes a memory circuit for storing an offset value detected by an offset value detection operation, which will be described later, and is added to a tilt adjustment signal obtained from the focusing coil drive circuit 10 when performing a tilt control operation in the recording / reproducing operation state. The tilt control circuit 13 is configured to generate the offset signal based on the offset value stored in the memory circuit 16.

  Reference numeral 17 denotes a laser drive circuit that supplies a drive signal to the laser diode 3 incorporated in the optical pickup 2, and 18 encodes a signal for recording a recording signal on the disk 1 and supplies the encoded signal to the laser drive circuit 17. It is a signal recording circuit and is configured to output an offset adjustment signal during an offset value detection operation.

  As described above, the optical disk recording / reproducing apparatus according to the present invention is configured. Next, the operation will be described. In a state where a normal recording operation or reproduction operation is performed, a focus error signal or a tracking error signal is generated from a signal obtained from the photodetector 4 incorporated in the optical pickup 2, and the generated error signal is generated. The pickup control circuit 8 performs a control operation for performing a focusing control operation and a tracking control operation based on the control.

When each control operation by the pickup control circuit 8 is performed, a control signal is output from the pickup control circuit 8 to the focusing coil drive circuit 10 and the tracking coil drive circuit 9. As a result, a driving signal is supplied from the focusing coil driving circuit 10 and the tracking coil driving circuit 9 to the focusing coil 5 and the tracking coil 6. Such a drive signal displaces the objective lens in a direction to reduce the level of the focus error signal or tracking error signal, so that focusing control for focusing the laser light emitted from the optical pickup 2 on the signal surface on the disk 1 is performed. It is possible to perform a tracking control operation that follows the operation and the signal track.

  As described above, the focusing control operation and tracking control operation by the pickup control circuit 8 are performed. Next, the tilt control method which is the gist of the present invention will be described.

  In the optical disc recording / reproducing apparatus according to the present invention, an offset value setting operation necessary for accurately performing the tilt control operation is performed before performing the recording operation. In the operation for such setting, a signal for performing an operation for setting an offset value is output from the offset detection circuit 15 to the tilt control circuit 13.

  Such an operation is a control operation in which a control signal for changing the tilt angle step by step from the tilt coil driving circuit 14 to the tilt adjusting coil 7 is outputted step by step in a state where the normal tilt control operation is not performed. Is done. When such a control signal is output from the tilt control circuit 13, the tilt of the objective lens from the tilt coil driving circuit 14 to the tilt adjusting coil 7 is stepped one step from the position most inclined to the other in the other direction. A drive signal for offset detection for changing is supplied. As a result, the objective lens is tilted step by step in the direction of tilt adjustment by the drive operation of the tilt adjustment coil 7.

  During the offset value detection operation, as described above, the operation of changing the tilt of the objective lens step by step by the signal output from the offset detection circuit 15 is performed. This operation is performed on the inner circumference side of the disc 1. This is performed while recording the offset adjustment signal in the provided test writing area A and signal recording area C.

  First, a case where an offset adjustment signal is recorded in the inner circumference side trial writing area A in order to set the inner circumference side offset value will be described. The operation of outputting an offset adjustment signal from the signal recording circuit 18 to the laser driving circuit 17 and recording the signal in the test writing area A on the inner circumference side of the disk 1 by the laser light emitted from the laser diode 7 is tilted. This is done while changing the angle step by step. When such an offset adjustment signal recording operation is performed, the relationship between the recording position and the level of the signal output from the offset detection circuit 15 is stored in the memory circuit 16 or the like.

  When the objective lens tilt changing operation based on the signal output from the offset detection circuit 15 is completed, the recording operation of the offset adjustment signal on the disk 1 is also stopped. When such an operation is completed, the optical pickup 2 is moved to the position where the recording operation of the offset adjustment signal in the test writing area A is started, and then the recorded offset adjustment signal is reproduced. Such a reproduction operation is performed in a state where a drive signal is not supplied to the tilt adjustment coil 7, that is, in a state where the objective lens is in a neutral position.

  When the recorded offset adjustment signal is reproduced while changing the angle of the objective lens with respect to the disk 1, the level of the RF signal obtained from the laser light reflected from the disk 1 changes. The offset adjustment signal recorded in the trial writing area A of the disk 1 is amplified by the RF signal amplification circuit 11 and then input to the β value detection circuit 12.

  As the inclination of the optical pickup 2 with respect to the signal surface of the disk 1 is adjusted in the correct direction, the A1 value obtained from the RF signal increases and the A2 value decreases. Therefore, when the recorded offset adjustment signal is reproduced while changing the tilt of the tilt stepwise, the β value gradually decreases after the β value becomes maximum.

  When the recorded offset adjustment signal is reproduced while stepwise changing the level of the drive signal supplied to the tilt adjustment coil 7, the β value obtained from the RF signal as the reproduction signal changes. Therefore, the value of the control signal output from the tilt control circuit 13 when the drive voltage at the position where the offset adjustment signal with the largest β value is recorded is supplied to the tilt adjustment coil 7. The operation of storing the value in the memory circuit 16 as the inner peripheral offset value is performed.

  As described above, the setting operation of the inner circumferential offset value using the test writing area A is performed. In the present invention, the outer circumferential offset value is set using the signal recording area C provided on the disc 1. Setting operation is performed. Such an operation is performed by, for example, moving the optical pickup 2 to the outermost peripheral position C3 of the signal recording area C based on the position information data recorded as a wobble signal on the disk 1, and then in the test writing area A described above. Since it can be performed by performing the same operation as the offset value detection operation, its description is omitted. The outer peripheral offset value set at the outermost peripheral position C3 of the signal recording area C is stored in the memory circuit 17.

  In FIG. 4, an area C1 is an area where a signal is recorded, an area C2 is an unrecorded area of a signal, and an area C3 on which an outer peripheral offset value setting operation has been performed is the last area of the area C2 which is the unrecorded area This is the outer peripheral area.

  As described above, the inner peripheral offset value and the outer peripheral offset value are stored in the memory circuit 16. Next, the tilt adjustment operation will be described.

  When the optical disk recording / reproducing apparatus is in a reproduction state or a recording state, when the relationship between the optical pickup 2 and the disk 1 needs to be adjusted in tilt, the tilt adjustment coil 7 is used to change the tilt of the objective lens. The drive signal supplied from the tilt coil drive circuit 14 is used to adjust the tilt adjustment signal for changing the tilt using the drive signal supplied from the focusing coil drive circuit 10 to the focusing coil 5. Is called.

  The drive signal supplied to the focusing coil 5 from the focusing coil drive circuit 10 is a signal in which an AC signal is superimposed on a DC voltage. That is, the DC voltage is a signal for displacing the position of the objective lens to the operating position, and the AC signal is a signal for displacing the objective lens by following the fast movement of the disk 1. The DC voltage described above is a signal for displacing the objective lens to the operating position in accordance with the positional relationship between the signal surface of the disk 1 and the optical pickup 2, and tilt adjustment is performed by utilizing the change in the DC voltage. I can do it.

  That is, since the DC voltage included in the drive signal supplied to the focusing coil 5 indicates the positional relationship between the objective lens and the signal surface of the disk 1, the DC voltage that changes corresponding to the position change on the disk. Indicates the tilt relationship between the objective lens and the disk 1. Therefore, the change in the DC voltage included in the drive signal supplied from the focusing coil drive circuit 10 to the focusing coil 5 is extracted as a tilt adjustment signal, and the extracted signal is stored in the memory circuit 16. The tilt adjustment operation can be performed by supplying the tilt coil driving circuit 14 with a signal obtained by adding the offset value calculated from the circumferential offset value and the offset value calculated on the outer circumferential side as a tilt control signal.

The offset value added to the signal extracted from the focusing coil drive circuit 10 is calculated and set according to the recording position from the inner peripheral offset value and the outer peripheral offset value. That is, the position of C3 which is the outermost peripheral area of the signal recording area C in which the outer peripheral offset value is set and the position on the test writing area A in which the inner peripheral offset value is set are obtained from the position information data. Therefore, the optimum offset value at the position on the disk 1 can be calculated from the distance between them and the change in the offset value.

  As a result of the tilt adjustment operation described above, the tilt coil drive circuit 14 supplies the tilt adjustment drive signal optimal for the recording / reproducing position to the tilt adjustment coil 7, so that the optical pickup 2 with respect to the disk 1 is supplied. An operation for adjusting the angle to an optimum state, that is, a tilt adjustment operation can be accurately performed.

  In the present embodiment, the tilt adjustment signal is obtained from the drive signal supplied to the focusing coil 5. However, the tilt adjustment signal is used for an apparatus configured to perform tilt adjustment using the level change of the RF signal. You can also

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

Explanation of symbols

1 disc
2 Optical pickup
3 Laser diode
4 photodetectors
5 Focusing coil
6 Tracking coil
7 Coil for tilt adjustment
8 Pickup Control Circuit 10 Focusing Coil Drive Circuit 11 RF Signal Amplifier Circuit 12 β Value Detection Circuit 13 Tilt Control Circuit 14 Tilt Coil Drive Circuit 15 Offset Detection Circuit 16 Memory Circuit 17 Laser Drive Circuit 18 Signal Recording Circuit

Claims (2)

A tilt control method for an optical disc recording / reproducing apparatus that uses an optical pickup having a tilt adjustment coil for adjusting the tilt of an objective lens and can record a signal on a rewritable disc. Record the offset adjustment signal while changing the level of the drive signal for offset detection supplied to the tilt adjustment coil in the provided test writing area, and then play back the recorded offset adjustment signal. The β value is detected from the RF signal to be detected, and the level of the drive signal supplied to the tilt adjustment coil when the signal having the maximum detected β value is recorded is set as the inner peripheral offset value. The level of the drive signal for offset detection supplied to the tilt adjustment coil is changed in the signal recording area When the offset adjustment signal is recorded and then the recorded offset adjustment signal is reproduced, the β value is detected from the reproduced RF signal, and the signal having the maximum detected β value is recorded. The level of the drive signal supplied to the coil for tilt adjustment is set as the outer peripheral offset value, and the tilt adjustment signal for tilt control is offset according to the recording position calculated from the inner peripheral offset value and the outer peripheral offset value. A tilt control method for an optical disc recording / reproducing apparatus, wherein tilt control is performed by adding values. 2. The tilt control method according to claim 1, wherein the setting operation of the outer peripheral side offset value is performed at the outermost peripheral position in the signal recording area.

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