WO2006088050A1

WO2006088050A1 - Optical disk unit

Info

Publication number: WO2006088050A1
Application number: PCT/JP2006/302637
Authority: WO
Inventors: Hiroshi Kayama; Kazuo Momoo; Seiji Nishiwaki; Jun-Ichi Asada; Shuichi Tasaka
Original assignee: Matsushita Electric Industrial Co., Ltd.
Priority date: 2005-02-16
Filing date: 2006-02-15
Publication date: 2006-08-24
Also published as: JP2008059619A

Abstract

An optical disk unit comprising a rotation-drive unit mounting an optical disk thereon and driven by rotation, a light source, an object lens condensing light from the light source toward the optical disk mounted on the rotation-drive unit, a light receiving element detecting the reflection light of the light by the optical disk to generate a detection signal, and an object lens control unit controlling the object lens based on the detection signal, wherein the object lens control unit controls the object lens during a recording or reproducing operation based on a detection signal obtained in advance in the data recorded area or non-recorded area of the optical disk.

Description

Specification

Optical disk device

Technical field

The present invention relates to an optical disc apparatus that optically records data on an optical disc and reproduces the data recorded on the optical disc apparatus, and a control method for the optical disc apparatus.

Background art

In an optical disc apparatus, it is necessary to control the optical beam force used for recording or reproduction so as to follow a track provided on the optical disc. This control is called tracking control. In addition, it is necessary to keep the light beam condensing state that irradiates the optical disk constant. This control is called focus control.

In recent years, optical discs with higher recording density have been developed. As the recording density of optical discs increases, the track pitch decreases and the size of pits and marks formed on the track also decreases. For this reason, it is necessary to increase the accuracy of tracking control and focus control of the light beam, and various techniques have been proposed.

[0004] In Patent Document 1, when performing recording / reproduction on an optical disc having a plurality of recording layers, the amount of emitted laser light, equalizer characteristics, tracking servo characteristics, focus servo characteristics, tilt servo characteristics, and tilt for each recording layer. It discloses that either the characteristics or the recording modulation waveform is set separately.

[0005] In Patent Document 2, when performing focus control and tracking control of a two-layer disc, a focus error signal due to reflected 0th-order light and first-order light is detected, and the layer that performs recording or reproduction is A method for canceling the influence of reflected light from another layer is disclosed.

[0006] Patent Document 3 proposes a method for adjusting an optical system so that an offset does not occur in a focus error signal.

[0007] Patent Document 4 discloses a method for adjusting a servo gain by measuring a closed loop characteristic of a tracking servo or a focus servo.

Patent Document 1: International Publication No. OOZ079525 Pamphlet

Patent Document 2: JP 2002-190132 A Patent Document 3: Japanese Patent Laid-Open No. 2003-196855

Patent Document 4: Japanese Patent Laid-Open No. 2003-157547

Disclosure of the invention

Problems to be solved by the invention

[0008] However, the tracking control and focus control according to the prior art do not take into consideration the influence of the data recording location and the unrecorded location in the recording layer where data is recorded or reproduced.

According to the study of the present inventor, an offset occurs in the tracking signal between the data recording location and the non-recording location in the recording layer, the reproduction signal or the recording signal is deteriorated, tracking control or The focus control became unstable, and it was easy to be out of control due to disturbance.

An object of the present invention is to provide an optical disc apparatus that can stably perform tracking control and focus control in view of such problems.

Means for solving the problem

[0011] An optical disc apparatus of the present invention places an optical disc on a rotary drive unit that rotates and drives, a light source, and condenses light of the light source power toward the optical disc placed on the rotary drive unit. An objective lens, a light receiving element that detects a reflected light of the light from the optical disc and generates a detection signal, and an objective lens control unit that controls the objective lens based on the detection signal, The objective lens control unit performs the recording or reproducing operation based on the detection signal obtained in the data recording area and the unrecorded area of the optical disc.

Then, the objective lens is controlled.

[0012] In a preferred embodiment, the optical disc apparatus further includes a preamplifier that generates an error signal indicating a positional deviation of the objective lens based on the detection signal, and the objective lens control unit includes data of the optical disc. For recorded and unrecorded areas! The error signal offset obtained during the recording or reproducing operation is corrected on the basis of the error signal obtained.

Preferably, according to an embodiment, the objective lens control unit calculates a DC offset value based on the amplitude of the error signal obtained by comprehension, and sets the calculated offset value to the calculated offset value. Based on this, the error signal offset obtained during the recording or playback operation is corrected.

[0014] Preferably, in one embodiment, the preamplifier generates an RF signal corresponding to data recorded on a track of the optical disc.

[0015] In one preferred embodiment, the optical disc apparatus detects, based on the RF signal, the recorded area and the unrecorded area in the user area of the optical disc and position information of these areas. The objective lens control unit stores the offset value in association with positional information of the recording area and the unrecorded area.

Preferably, according to an embodiment, the objective lens control unit causes the spot condensed toward the optical disk to be radially aligned in a user area including the recording area and the unrecorded area of the optical disk. The error signal offset value obtained by scanning is stored in association with the radial position.

Preferably, according to an embodiment, the objective lens control unit is configured based on the amplitudes of error signals obtained in the recording area and the unrecorded area in the recording information management area of the optical disc, respectively. The offset value of the error signal is calculated, and the offset of the error signal is corrected by switching the offset value based on the detection of the RF signal during the recording or reproducing operation.

According to a preferred embodiment, in the optical disc apparatus, the error signal is a tracking error signal, and the objective lens control unit controls the objective lens in the tracking direction.

In a preferred embodiment, in the optical disc apparatus, the error signal is a focus error signal, and the objective lens control unit controls the objective lens in a focus direction.

[0020] The disc control method of the present invention includes an optical disc mounted thereon, a rotational drive unit that rotationally drives the light source, and a light source, and condenses light from the light source toward the optical disc placed on the rotational drive unit. Control of an optical disc apparatus comprising an objective lens, a light receiving element that detects reflected light of the light from the optical disc and generates a detection signal, and an objective lens control unit that controls the objective lens based on the detection signal A data recording area of the optical disc And a step of controlling the objective lens during a recording or reproducing operation on the basis of a detection signal obtained by force in an unrecorded area.

Preferably, according to an embodiment, the step of controlling the objective lens includes the step of controlling the objective lens based on the detection signals obtained in the data recording area and the unrecorded area of the optical disc. A step (A) for generating an error signal indicating misregistration, and a step (B) for correcting the offset of the error signal obtained during the recording or reproducing operation based on the error signal. Including.

[0022] Preferably, in an embodiment, the step (A) calculates an offset value based on the amplitude of the error signal, and the step (B) is based on the calculated offset value. V, corrects the offset of the error signal obtained during recording or playback operation.

Preferably, according to an embodiment, the step (A) includes a recording area and data in which data of the optical disc is recorded based on an RF signal corresponding to data recorded on a track of the optical disc. Further, unrecorded areas that have been recorded and position information of these areas are further detected, and the step (B) performs recording based on the offset value and the position information of the recorded areas and unrecorded areas. Or, correct the offset of the error signal obtained during playback.

According to a preferred embodiment, in the embodiment, the step (A) includes an offset value of an error signal obtained by causing the position of the spot collected toward the optical disc to scan in the radial direction of the optical disc. Is calculated in association with the position in the radial direction, and the step (B) corrects the offset of the error signal obtained during the recording or reproduction operation based on the offset value and the position in the radial direction.

[0025] In a preferred embodiment, according to the embodiment, the step (A) is performed based on the amplitude of the error signal obtained in the recording area and the unrecorded area in the recording information management area of the optical disc. In step (B), the offset of the error signal is corrected by switching the offset value based on the detection of the RF signal during the recording or reproducing operation.

[0026] Preferably, according to an embodiment, the step (A) includes a step of forming the recording area by recording predetermined data in the recording information management area. In addition.

[0027] In a preferred embodiment, the error signal is a tracking error signal.

[0028] In a preferred embodiment, the error signal is a focus error signal.

[0029] An optical disc device of the present invention places an optical disc, and condenses light of a rotational drive unit that rotates and drives, a light source, and light source power toward the optical disc placed on the rotational drive unit. An objective lens, a light receiving element that detects a reflected light of the light from the optical disc and generates a detection signal, and an objective lens control unit that controls the objective lens based on the detection signal, The control gain of the objective lens is changed according to the type of the optical disk.

The invention's effect

[0030] According to the present invention, based on the detection signal obtained in advance in the data recording area and the unrecorded area of the optical disc, during the recording or reproducing operation, the objective lens Take control. For this reason, the influence of the recording state of the recording layer can be reduced, and the tracking and focus control of the optical disk can be stabilized.

Brief Description of Drawings

FIG. 1 (a) and (b) are block diagrams showing the configuration of an optical disc apparatus according to the present invention.

2 is a block diagram showing a structure of a preamplifier of the optical disc apparatus in FIG.

FIG. 3 shows a TE signal obtained when a recorded area and an unrecorded area are scanned.

[Fig. 4] (a) and (b) schematically show the state where the center of the light beam is aligned with the center of the track and the state where the center of the light beam is also shifted in the center force of the track. .

FIG. 5 is a schematic diagram showing a state in which a light beam is irradiated onto an optical disc having two recording layers.

[Fig. 6] (a) and (b) show a TE signal and an optical signal when recording and reproduction are performed on an optical disc having two recording layers, and a recording region of the recording layer is irradiated with a light beam. Shows the TE signal when the unrecorded area is irradiated with a light beam.

[FIG. 7] A diagram schematically showing a state in which reflected light irradiates a light receiving element. (A) shows recording / playback! /, Where the reflected light from the recording layer is symmetrical. (B) shows the case where the reflected light of the recording layer force when recording / reproduction is not performed is asymmetrical. Show the case of irradiating the child.

FIG. 8 shows a TE signal obtained when a recording area and an unrecorded area of a recording layer are continuously scanned on an optical disc having two recording layers, which is recorded and reproduced. .

FIG. 9 shows a TE signal obtained when a recorded area, an unrecorded area, and a recorded area of a recording layer are continuously scanned on an optical disc having two recording layers after recording and reproduction. ing.

FIG. 10 is a flowchart showing a tracking control procedure according to the present embodiment.

FIG. 11 is a diagram for explaining a DC offset component of a TE signal.

FIG. 12 is a flowchart showing another procedure of tracking control according to the present embodiment. 13] A schematic diagram for explaining a recording information management area of an optical disc.

FIG. 14 is a diagram showing an RF signal and a TE signal obtained from a recorded area and an unrecorded area.

FIG. 15 is a flowchart showing another procedure of tracking control according to the present embodiment. [16] This is a diagram showing how the TE signal amplitude changes due to AGC.

Explanation of symbols

101 optical disc

102 laser

103 PBS

104 collimating lens

105 1Z4 wave plate

106 Objective lens

107 Actuator

108 Spinner motor

109, 201, 501 Photo detector

110 Cylindrical lens

120 optical pickup

121 Signal processor 122 Servo section

123 traverse motor

124 preamplifier

125 controller

126 Laser drive

202, 203, 206, 207 Calorie calculator

204, 208 subtractor

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an embodiment of an optical disk device of the present invention will be described with reference to the drawings. 1 (a) and 1 (b) are block diagrams showing the configuration of the optical disk apparatus. The optical disc apparatus includes a spindle motor 108, an optical pickup 120, and a traverse motor 123. In addition, the optical disc apparatus includes a controller 125 that controls each unit.

The spindle motor 108 functions as a rotation driving unit that places the optical disc 101 and rotates the optical disc 101 at a predetermined rotational speed based on a command from the controller 125.

The optical pickup 120 irradiates the optical disc 101 with light for recording and reproduction. Further, the reflected light obtained by reflecting on the optical disc 101 is detected. The traverse motor 123 moves the optical pickup 120 to the optical disk 1 based on the command of the controller 125.

Move in the 01 radial direction.

The optical pickup 120 includes an objective lens 106, a 1Z4 wavelength plate 105, a collimating lens 104, a polarization beam splitter 103, a laser 102, a cylindrical lens 110, and a light receiving element 109.

The laser 102 functions as a light source, and light emitted from the laser 102 enters a collimating lens 104 through a polarization beam splitter (hereinafter abbreviated as PBS) 103 and is converted into parallel light.

The 1Z4 wavelength plate 105 changes the polarization state of parallel light. Specifically, it converts linearly polarized light into circularly polarized light. The objective lens 106 collimates the light so that a beam spot in a predetermined condensed state is formed on the data recording layer of the optical disc 101. The objective lens 106 can be moved in the focus direction F and the tracking direction (track crossing direction) T by the actuator 107. The light reflected by the optical disc 101 enters the 1Z4 wavelength plate 105 through the objective lens 106. The 1Z4 wavelength plate 105 converts circularly polarized light into linearly polarized light whose polarization plane is orthogonal to the forward path. The light transmitted through the 1Z4 wavelength plate 105 passes through the collimating lens 104, is reflected by the PBS 103, and enters the light receiving element 109 through the cylindrical lens 110. The light receiving element 109 outputs a detection signal corresponding to the incident light.

The optical disk device further includes a preamplifier 124, a signal processing unit 121, a servo unit 122, and a laser driving unit 126. As described in detail below, the preamplifier 124 generates a tracking error signal, a focus error signal, and an RF signal from the detection signal. The tracking error signal and the focus error signal indicate that the beam spot formed on the data recording layer of the optical disc 101 is shifted in the tracking direction when the objective lens 106 is displaced from an appropriate position in the tracking direction T and the focus direction F. And indicate that the beam meets the specified focusing condition. The RF signal includes information corresponding to data recorded data such as pits and marks formed in the data recording layer of the optical disc 101 and address information on the track on which the data is recorded.

[0040] The signal processing system 121 receives the RF signal and extracts address information. Also, information corresponding to the data recorded on the data recording layer of the optical disc 101 is reproduced.

As shown in FIG. 1B, the servo unit 122 includes an objective lens control unit 122a that controls the objective lens 106, and a motor control unit 122b that drives and controls the spindle motor 108 and the traverse motor 123. The objective lens control unit 122a receives the tracking error signal and the focus error signal, generates a control signal for controlling the objective lens 101, and generates a drive signal for driving the objective lens 106 based on the control signal. To do. For this purpose, the objective lens control unit 122a includes a tracking control unit 161, a tracking drive unit 162, a focus control unit 163, and a focus drive unit 164.

[0042] As will be described in detail below, the objective lens control unit 122a is intensively arranged in the recording area where the data of the optical disc 101 is recorded and the area where the data is recorded (unrecorded area). Based on the obtained detection signal, the objective lens 106 is controlled during the recording or reproducing operation. [0043] The laser driving unit 126 drives the laser 102 that emits a light beam used for recording and reproduction.

FIG. 2 is a block diagram showing a configuration for generating the tracking error signal and the focus error signal of the preamplifier 124. As shown in FIG. 3, the light receiving surface of the light receiving element 109 is divided into four light receiving regions, and a detection signal is obtained from each region. The preamplifier 124 includes a calorie calculator 202, 203, 206, 207 and a differential 204, 208.

The adder 202 and the adder 203 take the sum of signals obtained from the light receiving areas A and D and the light receiving areas B and C, respectively. The differential unit 204 takes the differential of the output signals of these adders 202 and 203. The output signal from the differential 204 becomes a tracking error signal (hereinafter referred to as a TE signal) by the push-pull method.

[0046] Adder 206 and adder 207 take the sum of signals from which light-receiving areas A and C and light-receiving areas B and D, which are located diagonally, are also obtained. The differential 208 takes the differential of the output signals of these adders 206 and 207. The output signal from the differential 204 becomes a focus error signal (hereinafter referred to as FE signal) by the astigmatism method.

Next, the DC offset that occurs in the tracking error signal will be described. When reproducing a recordable optical disk, the asymmetry of the intensity distribution of the light emitted from the objective lens 106, the abnormal shape of the land and group grooves of the optical disk to be reproduced, the radial tilt of the optical disk, the unrecorded recording layer A DC offset occurs in the TE signal due to the difference between the recording area and the recording area. FIG. 3 shows that a DC offset occurs in the TE signal at the boundary between the unrecorded area and the recorded area of the recording layer to be reproduced. That is, the center O ′ of the TE signal in the unrecorded area is shifted by Δ Δ with respect to the center O of the TE signal in the recorded area.

[0048] For this reason, when the tracking control is performed in accordance with the center O of the TE signal in the recording area, an offset potential corresponding to ΔO is superimposed on the TE signal in the unrecorded area. As a result, a shift occurs in tracking control. Specifically, as shown in FIG. 4 (a), the center O of the beam condensed by the objective lens 106 is correct in the recording area.

B

If it is controlled to match the center O of the track, in the unrecorded area,

T

As shown, the beam center OB is Control is done to match.

[0049] In addition, when an optical disc is provided with a plurality of recording layers, it is overlapped with a recording layer that is played back only at the boundary between the recording area and the unrecorded area of the recording layer that is played back. The boundary between the recorded area and the unrecorded area in another recording layer also affects the DC offset of the TE signal.

FIG. 5 schematically shows the optical disc 101 including the first recording layer 151 and the second recording layer 152. The entire first recording layer 151 is an unrecorded area, and the second recording layer 152 includes an unrecorded area 152a and a recorded area 152b. In the following, the case where the recording layer close to the objective lens 106 includes a recording area and an unrecorded area will be described, but the TE signal is similarly applied to a case where the recording layer away from the objective lens 106 includes a recording area and an unrecorded area. Affects the offset.

[0051] In such an optical disc, by focusing on the first recording layer 151 and performing force control, the light beam is moved in the track crossing direction (radial direction) T1 without performing tracking control. The obtained TE signals are shown in Figs. 6 (a) and (b). FIG. 6 (a) shows the case where the light beam is in the recording area 152b of the second recording layer 152, and FIG. 6 (b) is the case where the light beam is in the unrecorded area 152a of the second recording layer 152. Shows the case.

[0052] The focus of the light beam is controlled so as to coincide with the first recording layer 151, and both are TE signals obtained from the unrecorded area. Therefore, as is clear from Figs. 6 (a) and (b), the amplitudes of these TE signals are almost equal.

[0053] However, the recording state of the second recording layer that is out of focus is different, and the reflected light having the second recording layer force affects the TE signal. For this reason, an offset occurs in the TE signal due to the recording state of the second recording layer that is out of focus. In Fig. 6 (a), Q 'is the center of the TE signal, whereas in Fig. 6 (b), Q is the center of the TE signal.

As shown in FIG. 5, since the focus of the light beam is focused on the first recording layer 151, the spot of the light beam is large on the second recording layer. For this reason, a period in which the light beam scans across the boundary between the unrecorded area 152a and the recorded area 152b occurs.

FIGS. 7A and 7B show that the light receiving element 109 is irradiated with reflected light 502 from the first recording layer 151 and reflected light 503 from the second recording layer 152. Indicate state. In Figure 7 (a) Reflected light 503 from layers other than the recording or reproducing layer is uniformly incident on the light receiving element 109, and FIG. 7 (b) schematically shows that the light is incident unevenly.

[0056] In the case shown in FIG. 7 (b), when the reflectance of the second recording layer 152 changes due to, for example, passing through a recording area and an unrecorded area, FIG. 6 (a) and FIG. The TE signal offset changes as shown in (b). As the light beam moves in the track crossing direction T1, the ratio including the recording area 152b and the unrecorded area 152a also changes, and the position of the reflected light 503 relative to the light receiving element 109 also changes. As a result, as shown in FIG. 8, the TE signal offset gradually changes while the light beam irradiates the boundary between the recording area and the unrecorded area of the first recording layer 151. In FIG. 8, TE signals 401 and 403 are obtained when the light beam is completely in the recorded area and completely in the unrecorded area, and TE signal 402 straddles the recorded area and the unrecorded area. Obtained in case. The center of the TE signal changes from P to P '. For this reason, in the TE signal 402, the offset gradually changes.

[0057] As shown in FIG. 9, when recording or reproduction is performed and an unrecorded area is sandwiched between two recorded areas in another recording layer, The TE signal offset gradually changes at the two boundaries with the recording area. As shown in FIG. 9, when the entire light beam is in the recording area, the center of the TE signal 401 is at the P level, and the offset of the TE signal 402 gradually increases while the light beam straddles the recording area and the unrecorded area. Become bigger. When the entire light beam enters the unrecorded area, the center of the TE signal 403 becomes P ′ level. In addition, the light beam straddles the boundary between the unrecorded area and the recorded area, and the offset of the TE signal 404 gradually decreases in the meantime. When the entire light beam again enters the recording area, the center of the TE signal 405 becomes P It becomes the level of.

[0058] The optical disc apparatus according to the present embodiment suppresses the change in the offset of the TE signal that occurs between the recording area and the unrecorded recording area of the optical disc, thereby realizing more stable tracking control. Hereinafter, tracking control in the optical disc apparatus of the present embodiment will be described with reference to the flowchart shown in FIG. 10 and FIGS. 1 (a) and 1 (b). This control method is called the first method.

First, the case where the optical disk power is provided with only one recording layer will be described. When the recordable optical disk 101 is loaded in the optical disk apparatus, the optical disk apparatus initializes the memory and the like. Then, each part of the optical pickup is set to an initial state, and control is started (step S101). Next, focus control and tracking control are started (step S102).

[0060] As shown in step S103, the optical pickup 102 was moved to the inner peripheral side of the optical disc 101, and the recording information management area provided in the innermost peripheral portion of the optical disc 101 was irradiated with light. When the signal processing unit 121 decodes the RF signal, the information recorded in the recording information management area is read out. The recording information management area records information on whether or not data is recorded at least on the recording layer. If the controller 125 determines that the read information force has been recorded, it detects which region of the recording layer is a recorded force (step S104). Specifically, light is irradiated over the entire user area of the optical disc, and the signal processing unit 121 decodes the obtained RF signal to determine whether data is written, that is, the recording area. Detects whether the area is a force unrecorded area. Also, the position information of the area is acquired. As the position information, an address included in the RF signal may be used, or a radial position associated with the address may be used. Alternatively, only position information on the boundary between the recording area and the unrecorded area may be acquired.

[0061] As shown in step S105, the tracking control section 161 obtains a TE signal and obtains a DC offset value in the recording area and the non-recorded area. As shown in Fig. 11, the DC offset value can be obtained by obtaining the upper and lower envelopes of the TE signal and finding the difference between the average and the reference value (GND). The maximum and minimum values of the TE signal may be obtained, and the difference between the average and the reference value (GND) may be obtained. The tracking control unit 161 stores the obtained DC offset value in association with positional information of the recording area, the unrecorded area, and Z or their boundaries.

[0062] When the optical disc apparatus receives a command for recording or reproduction by the user, as shown in step S106, the tracking control unit 161 receives the TE signal obtained during the recording or reproduction operation, and obtains it by the above procedure. The TE signal offset is corrected based on the stored DC offset value and the position information of the recording area, unrecorded area or boundary. More specifically, the stored DC offset value is selected by using the position information of the recorded area, the unrecorded area, or the position information of the boundary between them, and is overlapped with the TE signal in FIG. The offset is corrected using the selected DC offset value so that the offset ΔO is canceled. Using the corrected TE signal, the tracking control unit 161 generates a control signal and outputs it to the tracking drive unit 162. The tracking drive unit 162 generates a drive signal corresponding to the received control signal and applies the drive signal to the actuator 107. Thus, stable tracking control can be performed without being affected by the presence or absence of recording on the recording layer.

[0063] Note that the tracking control does not necessarily need to be controlled with the center of the TE signal as a target. For example, when reproducing a recorded signal, the jitter characteristic is improved or the amplitude is maximized. You can set it to. When recording, it may be set so that the jitter characteristics after recording are good or the amplitude is maximized, and the address information recorded on the optical disc is easy to read! You can set it like /!

If it is determined in step S103 in FIG. 10 that the loaded optical disc 101 is not recorded, the recording operation may be started without correcting the TE signal. Since there is no recording area in the recording layer of the optical disc, the TE signal is offset as described above.

However, when it is necessary to read the address of an already recorded area, such as when recording is interrupted and resumed during the recording operation, it is necessary to perform tracking control on the recorded area and the unrecorded area. In this case, the TE signal may be corrected using the recorded information management area.

For example, as shown in FIG. 13, a recording information management area 161 is provided on the innermost periphery of the optical disc 101. In this area, data 163 indicating information on the optical disc 101 is recorded in advance. Therefore, an area where the data 163 is recorded can be used as a recording area, and the area can be used as an unrecorded area 165 when data is recorded. Alternatively, the recording area may be formed by performing test recording in an unrecorded area of the recorded information management area 161.

[0067] In this case, in FIG. 11, after executing step S103 and reading the data in the recording information management area to determine whether or not the optical disc has been recorded, it is shown in FIG. As described above, test recording is performed in the recording information management area to form a recording area (step S1 08). This test recording is for purposes other than the TE signal offset adjustment, such as recording power adjustment. Even if it is formed by. As described above, test recording is not necessary when using the recording area already formed in the recording information management area.

[0068] Next, as shown in step S109, the DC offset value of the TE signal is measured in the recording area and the unrecorded area of the recording information management area. In this case, the DC offset value is stored in the tracking control unit as the DC offset value in the recording area and the DC offset value in the unrecorded area, that is, in association with the recording area or the unrecorded area.

[0069] When the optical disc apparatus receives a user force recording or reproducing command, as shown in step S110, the tracking control unit 161 receives the TE signal obtained during the recording or reproducing operation, and stores the stored DC offset value. Use to correct the TE signal offset. In this case, the position information of the recorded area, the unrecorded area, or the boundary between them cannot be used. For this reason, RF signals are used to switch DC offset values. As shown in FIG. 14, when the light beam enters the recording area force unrecorded area during tracking control, the RF signal changes from signal 410 to signal 411 as shown in FIG. Therefore, when the signal processing unit 121 detects a change in the waveform or amplitude level of the RF signal and determines that the scanning force of the light beam has changed to the recording area force, the stored DC offset is stored. Change the value to correct the TE signal. As a result, stable tracking control is realized.

[0070] It should be noted that this control method may be used for a recorded optical disc! When correcting the TE signal for a recorded optical disk, the RF signal that does not switch the stored DC offset value based on the position information of the recorded area, unrecorded area, or these boundaries is used. You can use it to switch.

In the above-described embodiment, the DC offset value is stored in association with position information such as a recording area, or in association with a recording area force unrecorded area. However, the DC offset value may be stored in association with the radial position of the optical disk and the TE signal may be corrected based on the stored value without determining whether the recording area is strong. . This method is called the second control method.

[0072] As shown in FIG. 15, the optical disc apparatus is a memory initialization and optical pickup. Each part is set to an initial state and control is started (step S111). Next, focus control is started (step S112). No tracking control! /.

[0073] Similar to the above-described procedure, it is determined whether or not the optical disc 101 has been recorded (step S113).

) o

If the disc is a recorded disc, as shown in step S114, the optical beam is scanned in the cross-track direction, and the TE signal is obtained over the entire radial direction in the user area of the optical disc 101. Then, the DC offset value at each radial position is obtained by the above-described calculation. The obtained DC offset value is stored in association with the radial position (step S1 15).

[0075] A stepping motor or the like is usually used as the traverse motor. Therefore, the radial position can be determined from the pulse signal given to the stepping motor and the movement amount of the optical pickup.

[0076] When the optical disc apparatus receives a command of user force recording or reproduction, as shown in step S116, the tracking control unit 161 receives and stores the TE signal obtained during the recording or reproduction operation. The TE signal offset is corrected based on the value and the radial position from which the value was obtained. This makes it possible to perform stable tracking control that is not affected by the presence or absence of recording on the recording layer.

[0077] According to this method, not only the offset generated in the TE signal depending on whether the recording area force is an unrecorded area, but also the influence of the DC offset generated due to the tilt in the optical disc can be reduced. In addition, the effect of TE signal offset caused by all causes, such as birefringence and reflectivity changing depending on the radial position, can be reduced. Therefore, more stable tracking control can be performed.

Next, tracking control when the optical disc includes a plurality of recording layers will be described.

When the optical disc has a plurality of recording layers, the second control method described with reference to FIG. 15 is used to determine whether or not the recording area is an optical disc for each recording layer. It is preferable to store a DC offset value in association with the position in the radial direction and correct the TE signal based on the stored value. This compensates for the offset by comprehensively considering the effect of DC offset caused by recording layers other than the recording layer to be recorded or reproduced. Can be corrected.

In addition, when the first control method described with reference to FIG. 10 is used, as described with reference to FIG. 8, the boundary portion between the recording area and the non-recording area in another recording layer is used. It is necessary to consider the impact. Therefore, during the recording or reproducing operation, the DC offset value when the other recording layer is the recording area and the unrecorded area are present at the boundary between the recording area and the unrecorded area in the other recording layer. It is preferable to correct the TE signal using a value between the DC offset value of the case (for example, an intermediate value thereof). In addition, the extent of the boundary area may be measured in advance. For example, in step S104 in FIG. 10, after the recording area is detected and the boundary position is confirmed in the recording layer, the force control is moved to another recording layer, and the boundary becomes a TE signal. Find the range that affects you in detail and store the address of the range that affects it together.

[0080] The control when the optical disc is unrecorded is the same as that of the optical disc including one recording layer.

As described above, the force described in the present embodiment for tracking control. The present invention can also be applied to offset reduction in focus control. In a single-layer or multi-layer optical disc, when a recording area and an unrecorded area exist, an offset may occur in the focus error signal. In such a case, after the focus control is started and before the recording or reproduction operation, for example, the force position where the TE signal is maximized over the entire circumference of the optical disk. Measure the focus position where the maximum is, the focus position where the jitter of the RF signal is minimum, and the force position where the address signal can be read with the highest quality. The focus point is stored together with position information such as an address and a radial position. Next, during the recording or reproducing operation, the force control can be stably performed by correcting the focus error signal by using the stored focus point and its position information.

As described above, the reason why the offset superimposed on the TE signal or the FE signal has an adverse effect on the stability of the tracking control or the focus control and the solution thereof have been described as the present embodiment. However, factors that can cause tracking control and focus control to become unstable include gain fluctuations in addition to offset. [0083] In an optical disc apparatus, tracking control uses a tracking sum (TS) signal or a signal equivalent to TS, and is automatically controlled so that the amplitude is constant (AGC, called auto gain control) TE signal Is used. Focus control uses a focus sum (FS) signal or a signal equivalent to FS, and uses an FE signal controlled by AGC. For this reason, for example, in tracking control, in the case of an optical disc having a different amplitude ratio between the TS signal and the TE signal, the TE signal amplitude after AGC also differs. Figure 16 shows the relationship between the TS signal, the TE signal before AGC, and the TE signal after AGC. Using the TS signal 451 and the TE signal 453, the TE signal 456 controlled by the AGC increases in amplitude.

[0084] The TE signal 457 controlled by the AGC using the same TE signal 454 as the TS signal 452 and the TE signal 4 53, in which the DC offset voltage is superimposed on the TS signal 451, is reduced in amplitude. End up. In the TS signal 452, the amplitude of the AC component does not change, but by superimposing the DC offset voltage, the amplitude of the TS signal apparently increases, and as a result, the amplitude of the TE signal decreases by AGC. This is because it was controlled. Such a problem also occurs in the FE signal.

[0085] This is because, in an optical disc having a plurality of recording layers, recording or reproduction is performed, and reflected light from a recording layer different from the recording layer is incident on the light receiving element, resulting in a DC offset. Due to

[0086] In such a case, for example, before inputting the TE signal to the AGC circuit, or by adding a circuit for performing gain adjustment or a circuit having an equivalent function to the output side of the AGC circuit, Servo gain fluctuation can be suppressed depending on the type. As a result, tracking control and tracking control can be made more stable.

If such a circuit is added to the above-described embodiment, the tracking control can stabilize the focus control more frequently.

Industrial applicability

[0088] The present invention can be suitably used for various optical disk devices, and in particular, can be suitably used for an optical disk device corresponding to an optical disk having a plurality of recording layers.

Claims

The scope of the claims

[1] A rotation drive unit that carries an optical disk and rotates,

A light source;

An object lens for condensing the light of the light source power toward the optical disk placed on the rotation drive unit;

A light receiving element that detects reflected light of the light from the optical disc and generates a detection signal; and an objective lens control unit that controls the objective lens based on the detection signal; and

The objective lens control unit is an optical disc apparatus that controls the objective lens during a recording or reproducing operation based on a detection signal obtained in a data recording area and an unrecorded area of the optical disc.

[2] The apparatus further includes a preamplifier that generates an error signal based on the detection signal indicating the positional deviation of the objective lens,

The objective lens control unit corrects an offset of an error signal obtained during a recording or reproducing operation based on an error signal obtained in a data recording area and an unrecorded area of the optical disc. 1. The optical disc device according to 1.

[3] The objective lens control unit calculates a DC offset value based on the amplitude of the error signal obtained by comprehension, and performs a recording or playback operation based on the calculated offset value. 2. The optical disc apparatus according to claim 1, wherein an offset of the obtained error signal is corrected.

4. The optical disc apparatus according to claim 3, wherein the preamplifier generates an RF signal corresponding to data recorded on a track of the optical disc.

[5] The apparatus further includes a signal processing unit that detects the recording area and the unrecorded area in the user area of the optical disc based on the RF signal, and position information of these areas, and the objective lens control unit includes the offset 5. The optical disc apparatus according to claim 4, wherein the value is stored in association with position information of the recording area and the unrecorded area.

[6] The objective lens control unit scans the spot condensed toward the optical disc within the user area including the recording area and the non-recording area of the optical disc, and performs radial scanning. 4. The optical disc apparatus according to claim 3, wherein the offset value of the error signal obtained by performing the processing is stored in association with the radial position.

[7] The objective lens controller is configured to set an offset value in each area based on the amplitude of the error signal obtained in the recording area and the unrecorded area in the recording information management area of the optical disc. 5. The optical disk device according to claim 4, wherein the offset of the error signal is corrected by calculating the offset value based on detection of the RF signal during the recording or reproduction operation.

8. The optical disc apparatus according to claim 2, wherein the error signal is a tracking error signal, and the objective lens control unit controls the objective lens in a tracking direction.

9. The optical disc apparatus according to claim 2, wherein the error signal is a focus error signal, and the objective lens control unit controls the objective lens in a focus direction.

[10] A rotation driving unit for mounting and rotating the optical disk, a light source, an objective lens for condensing light from the light source toward the optical disk mounted on the rotation driving unit, and the optical disk. A method for controlling an optical disc apparatus, comprising: a light receiving element that detects reflected light of the light and generates a detection signal; and an objective lens control unit that controls the objective lens based on the detection signal. ,

The objective lens is controlled during the recording or reproducing operation based on the detection signal obtained in advance in the data recording area and the unrecorded area of the optical disc. A method of controlling an optical disc apparatus including steps.

[11] The step of controlling the objective lens comprises:

(A) generating an error signal indicating a positional deviation of the objective lens based on the detection signals obtained in the data recording area and the unrecorded area of the optical disc;

(B) correcting the offset of the error signal obtained during the recording or reproducing operation based on the error signal;

11. The method of controlling an optical disc apparatus according to claim 10, comprising:

[12] The step (A) calculates an offset value based on the amplitude of the error signal, and the step (B) performs a recording or reproduction operation based on the calculated offset value. 12. The method of controlling an optical disk device according to claim 11, wherein the error signal offset obtained is corrected.

[13] In the step (A), based on the RF signal corresponding to the data recorded on the track of the optical disc, the recording area on which the data on the optical disc is recorded and the data are recorded. Further detecting the location information of these areas,

13. The step (B) corrects an error signal offset obtained during a recording or reproducing operation based on the offset value and position information of the recorded area and the unrecorded area. The control method of the optical disk apparatus described.

[14] In step (A), the offset value of the error signal obtained by scanning the optical disc in the radial direction for the spot position focused toward the optical disc is calculated in association with the radial position. And

13. The method of controlling an optical disc device according to claim 12, wherein the step (B) corrects an error signal offset obtained during a recording or reproducing operation based on the offset value and a radial position.

[15] The step (A) is performed in each of the recording area and the unrecorded area in the recording information management area of the optical disc based on the amplitude of the error signal obtained. Calculate the offset value,

13. The method of controlling an optical disk device according to claim 12, wherein the step (B) includes correcting the offset of the error signal by switching the offset value based on detection of the RF signal during the recording or reproducing operation. .

16. The optical disk according to claim 15, wherein the step (A) further includes a step of forming the recording area by recording predetermined data in the recording information management area. Control method of the device.

17. The method of controlling an optical disc apparatus according to claim 10, wherein the error signal is a tracking error signal.

18. The method of controlling an optical disc apparatus according to claim 10, wherein the error signal is a focus error signal.