JP2012256385A - Optical disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical disk device capable of suppressing dispersion in an adjustment using a tracking error signal as an index in starting.SOLUTION: When performing an adjustment using the tracking error signal as the index in starting the optical disk device, the optical disk device turns off automatic gain control of the tracking error signal (refer to Step S130) in the adjustment of the whole recording layers of the optical disk.

Description

  The present invention relates to an optical disc apparatus, and more particularly to an optical disc apparatus that can handle a single-sided multilayer optical disc having a plurality of recording layers on one side.

  In recent years, single-sided multilayer optical discs having a plurality of recording layers on one side have become widespread. In a conventional optical disc apparatus capable of handling a single-sided multilayer optical disc, adjustments are made on each recording layer in the following procedure at startup.

  First, the optical disk is rotated, and the number of recording layers of the optical disk is obtained by focus search. Next, after performing spherical aberration correction using the set value for L0 measured in advance in the manufacturing process of the apparatus, automatic gain control (automatic amplitude adjustment) of the focus error signal is performed, and the laser beam is incident from the side. Focus control is drawn into the farthest recording layer L0. Then, coarse adjustment of spherical aberration correction is performed using the tracking error signal as an index, and then automatic gain control of the tracking error signal is performed to pull in the tracking control. After that, fine adjustment for spherical aberration correction is performed using the RF signal as an index, and loop gain adjustment for focus control and loop gain adjustment for tracking control are performed.

  After that, the focus jump is made to the recording layer L1 far from the side where the laser beam is incident next, and the spherical aberration correction is performed with the set value for L1 measured in advance in the manufacturing process of the apparatus, and then focus control is drawn into L1. . Then, coarse adjustment of spherical aberration correction is performed, and then tracking control is pulled in. After that, fine adjustment for spherical aberration correction is performed, and loop gain adjustment for focus control and loop gain adjustment for tracking control are performed. When recording layers after L2 exist, the same adjustment as in the case of L1 is performed in order, and when the adjustment for all the recording layers is completed, the start-up is ended. When this activation is completed, the optical disk can be played back.

Japanese Patent No. 4377841 (paragraphs 0048 to 0050, FIG. 22, and claim 20) JP 2006-318590 A Japanese Patent No. 4257049 JP 2010-272164 A

  In the adjustment at each recording layer at the start-up described above, the coarse adjustment of the spherical aberration correction at L0 is performed with the automatic gain control of the tracking error signal being OFF, and the rough adjustment of the spherical aberration correction at the recording layers after L1. Is performed when the automatic gain control of the tracking error signal is ON.

  However, when the automatic gain control of the tracking error signal is in the ON state, according to the change in the total sum of each electrical signal output from the photodetector in the optical pickup (the signal that becomes the original signal that generates the tracking error signal). In order to adjust the amplitude of the tracking error signal, when the amount of light received by the photodetector decreases during the coarse adjustment of spherical aberration correction, an operation to correct the amplitude change of the tracking error signal due to the decrease is added. The tracking error signal amplitude becomes difficult to understand. For this reason, there has been a problem that variation in coarse adjustment of spherical aberration correction in the recording layers after L1 is large.

  In Patent Document 1, an operation for temporarily turning off automatic gain control of a tracking error signal is started. This operation is an operation at the time of an interlayer jump in a recording or reproducing state. This is completely unrelated to the adjustment at start-up.

  In view of the above situation, an object of the present invention is to provide an optical disc apparatus capable of suppressing variations in adjustment using a tracking error signal at the time of activation as an index.

  In order to achieve the above object, an optical disc apparatus according to the present invention is an optical disc apparatus capable of supporting a single-sided multilayer optical disc having a plurality of recording layers on one side, and irradiates the optical disc with light and returns light from the optical disc. An optical pickup for detecting the signal by a photodetector, tracking error signal generating means for processing the electrical signal output from the photodetector to generate a tracking error signal, and the amplitude level of the tracking error signal to a predetermined level The automatic gain control means for performing the automatic gain control of the tracking error signal, and the adjustment means for performing the adjustment using the tracking error signal as an index when the optical disk apparatus is activated. When performing adjustment using the tracking error signal as an index at the start of In the adjustment of the entire recording layer of the serial optical disk, a configuration in which the automatic gain control of said tracking error signal by the automatic gain control unit to the OFF state.

  According to such a configuration, it is easy to detect a variation in the amplitude level of the tracking error signal during adjustment using the tracking error signal as an index at the time of start-up. Can be suppressed.

  In addition, the adjusting means has movable lens position adjusting means for adjusting and controlling the position of a spherical aberration correcting movable lens disposed in the optical system of the optical pickup, and the tracking error signal is output when the optical disc apparatus is activated. As an index, the position of the movable lens for spherical aberration correction may be roughly adjusted using the movable lens position adjusting means.

  Moreover, it is desirable to be able to support BD conforming to the BDXL standard.

  According to the optical disk device of the present invention, it is possible to suppress variations in adjustment using the tracking error signal at the time of activation as an index.

1 is a diagram showing a schematic configuration of an optical disc apparatus according to an embodiment of the present invention. 1 is a diagram illustrating a schematic configuration of an optical pickup provided in an optical disc device according to an embodiment of the present invention. It is a figure which shows the light-receiving area | region of a photodetector. It is a figure which shows schematic structure of a tracking error signal generation circuit. 4 is a flowchart showing a start-up operation of the optical disc apparatus according to the embodiment of the present invention. It is a figure which shows the characteristic line regarding the amplitude level of RF signal and tracking error signal corresponding to the optical disk apparatus which concerns on one Embodiment of this invention. It is a figure which shows the characteristic line regarding the amplitude level of RF signal and tracking error signal corresponding to the conventional optical disk apparatus.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic configuration of an optical disc apparatus according to an embodiment of the present invention.

  An optical disk apparatus according to an embodiment of the present invention is an optical disk apparatus that can handle a single-sided multilayer optical disk, and includes an optical pickup 1, an RF amplifier 31, a DSP (Digital Signal Processor) 32, a reproduction processing circuit 33, An output circuit 34, a CPU (Central Processing Unit) 41, a driver 42, a display unit 43, an operation unit 44, a feed motor 51, and a spindle motor 52 are provided.

  The optical pickup 1 irradiates the optical disc 2 with a light beam and reads various information such as audio information and video information recorded on the optical disc 2. The optical pickup 1 includes an infrared laser beam (CD (Compact Disc) laser beam) having a wavelength of 780 nm, a red laser beam (DVD (Digital Versatile Disc) laser beam) having a wavelength of 650 nm, and a blue having a wavelength of 405 nm. The optical disc 2 can be irradiated with a laser beam (BD (Blu-ray Disc: registered trademark) laser beam). Details of the inside of the optical pickup 1 will be described later.

  Audio information and video information obtained by the optical pickup 1 are converted into audio and video by the RF amplifier 31, DSP 32, reproduction processing circuit 33, and output circuit 34, and output from a speaker and a monitor (not shown), respectively. The RF amplifier 31 amplifies an audio signal, a video signal, etc. from the optical pickup 1. The DSP 32 and the reproduction processing circuit 33 perform various information processing (for example, video processing) for reproduction on the signal from the RF amplifier 31. The output circuit 34 performs D / A conversion processing and the like in order to output the signal from the reproduction processing circuit 33 to a speaker and a monitor (not shown).

  The DSP 32 performs arithmetic processing based on a signal output from the photodetector 20 (see FIG. 2), and generates a focus error signal, a focus servo signal, a tracking error signal, and the like.

  The CPU 41 receives information from the operation unit 44 and transmits it to the DSP 32, and transmits information from the DSP 32 to the display unit 43.

  The driver 42 controls the operations of the feed motor 51 and the spindle motor 52 based on instructions from the DSP 32. The feed motor 51 moves the optical pickup 1 in the radial direction of the optical disc 2. The spindle motor 52 drives the optical disc 2 in the rotation direction.

  The driver 42 also controls operations of the actuator 21 and the BEX (Beam Expander) motor 22 (see FIG. 2) in the pickup device 1 based on an instruction from the DSP 32.

  Next, FIG. 2 shows a schematic configuration of the optical pickup 1 provided in the optical disc apparatus according to the embodiment of the present invention.

  The optical pickup 1 includes a first light source 10a, a second light source 10b, a first grating 11a, a second grating 11b, a dichroic prism 12, a collimator lens 17, a beam splitter 14, a rising mirror 15, A quarter-wave plate 16, a collimator lens 17, an objective lens 18, a detection lens 19, a photodetector 20, an actuator 21, and a BEX motor 22 are provided.

  The first light source 10a is a two-wavelength integrated LD that can emit an infrared laser beam (CD laser beam) having a wavelength of 780 nm and a red laser beam (DVD laser beam) having a wavelength of 650 nm. The second light source 10b is an LD capable of emitting a 405 nm band blue laser beam (BD laser beam).

  The first grating 11 a diffracts the laser beam emitted from the first light source 10 a and outputs the diffracted light to the dichroic prism 12. The second grating 11b diffracts the laser beam emitted from the second light source 10b and outputs the diffracted light to the dichroic prism 12.

  The dichroic prism 12 transmits the diffracted light output from the first grating 11a and reflects the diffracted light output from the second grating 11b. And the optical axis of the diffracted light radiate | emitted from the 1st grating 11a and the 2nd grating 11b is made to correspond. The diffracted light (laser beam) transmitted or reflected by the dichroic prism 12 is sent to the collimating lens 17.

  The collimator lens 13 converts the laser beam sent from the dichroic prism 12 into parallel light. The laser beam converted into parallel light by the collimator lens 17 is sent to the beam splitter 14.

  The beam splitter 14 functions as a light separating element that separates the incident laser beam, transmits the light beam transmitted from the collimating lens 17, guides it to the optical disc 2 side, and reflects the reflected light reflected by the optical disc 2. Is reflected and guided to the photodetector 20 side. The laser beam that has passed through the beam splitter 14 is sent to the raising mirror 15.

  The raising mirror 15 reflects the light beam transmitted through the beam splitter 14 and guides it to the optical disc 2. The rising mirror 15 is inclined by 45 ° with respect to the optical axis of the laser beam sent from the beam splitter 14, and the optical axis of the laser beam reflected by the rising mirror 15 is the same as that of the optical disc 2. Nearly perpendicular to the recording surface.

  The quarter-wave plate 16 has a function of converting linearly polarized light into circularly polarized light and converting circularly polarized light into linearly polarized light. The linearly polarized laser beam reflected by the rising mirror 15 is converted into circularly polarized light and collimated. The circularly polarized laser beam which is sent to the lens 17 and reflected from the optical disk 2 is converted into linearly polarized light and sent to the rising mirror 15.

  The collimating lens 17 can be moved in the optical axis direction (vertical direction in FIG. 2) by the BEX motor 22. According to the movement of the collimating lens 17, the state of the laser beam emitted from the collimating lens 17 can be divergent light or convergent light. The spherical aberration can be corrected by changing the state of the laser beam emitted from the collimating lens 17 in this way. The laser beam emitted from the collimating lens 17 is sent to the objective lens 18.

  The objective lens 18 condenses the laser beam sent from the collimating lens 17 on the recording surface of the optical disc 2. The objective lens 18 can be moved, for example, in the vertical and horizontal directions in FIG. 2 by an actuator 21 described later, and the position thereof is controlled based on the focus servo signal and the tracking servo signal.

  The reflected light reflected by the optical disk 2 passes through the objective lens 18, the collimating lens 17, and the quarter wavelength plate 16 in this order, and after being reflected by the rising mirror 15, is further reflected by the beam splitter 14 to be detected by the detection lens. The light is condensed by 19 to a light receiving element provided on the photodetector 20.

  The photodetector 20 converts optical information received using a light receiving element such as a photodiode into an electrical signal and outputs the electrical signal to the DSP 32 (see FIG. 1). As shown in FIG. 3, the photodetector 20 includes main light receiving areas A to D that are equally divided into four vertically and horizontally, sub light receiving areas E and F that are equally divided horizontally and two equally horizontally. The sub-light receiving areas G and H are divided, and photoelectric conversion is individually performed for each area to output an electric signal. The main light receiving areas A to D are areas for receiving 0th order diffracted light (main beam), and the sub light receiving areas E to H are areas for receiving 1st order diffracted light (subbeam). The DSP 32 may generate a focus error signal by subtracting the sum of the electrical signal SB of the region B and the electrical signal SD of the region D from the sum of the electrical signal SA of the region A and the electrical signal SC of the region C. The focus sum signal can be generated by adding the electric signals SA to SD in the areas A to D. The DSP 32 has a tracking error signal generation circuit, and the tracking error signal generation circuit generates a tracking error signal from the electric signals SA to SH in the areas A to H. Details of the tracking error signal generation circuit will be described later.

  The actuator 21 moves the objective lens 18 in the radial direction of the optical disc 2 in accordance with the objective lens drive signal generated and output by the driver 42 (see FIG. 1).

  In addition to the tracking operation for moving the objective lens 18 in the direction along the recording surface of the optical disc 2, the actuator 21 tilts the objective lens 18 so that the optical axis of the laser beam emitted from the objective lens 18 swings. An operation and a focusing operation for moving the objective lens 18 toward and away from the optical disc 2 can also be performed.

  Next, FIG. 4 shows a schematic configuration of a tracking error signal generation circuit included in the DSP 32. The tracking error signal generation circuit shown in FIG. 4 includes variable gain amplifiers 61 to 68, adders 69 to 72, a main differential amplifier 73, a sub differential amplifier 74, attenuators 75 and 76, and a composite differential amplifier. 77.

  The adder 69 adds the electric signal SA amplified by the variable gain amplifier 61 and the electric signal SB amplified by the variable gain amplifier 62, and sends the added signal to the non-inverting input terminal of the main differential amplifier 73. Output. The adder 70 adds the electric signal SC amplified by the variable gain amplifier 63 and the electric signal SD amplified by the variable gain amplifier 64, and outputs the added signal to the inverting input terminal of the main differential amplifier 73. To do. The main differential amplifier 73 generates a main push-pull signal from the output signals of the adders 69 and 70 and outputs it to the attenuator 75. The attenuator 75 attenuates the main push-pull signal and outputs the attenuated signal to the non-inverting input terminal of the composite differential amplifier 77.

  The adder 71 adds the electric signal SE amplified by the variable gain amplifier 65 and the electric signal SF amplified by the variable gain amplifier 66, and the added signal is supplied to the non-inverting input terminal of the sub differential amplifier 74. Output. The adder 72 adds the electric signal SG amplified by the variable gain amplifier 67 and the electric signal SH amplified by the variable gain amplifier 68, and outputs the added signal to the inverting input terminal of the sub differential amplifier 74. To do. The sub differential amplifier 74 generates a sub push-pull signal from the output signals of the adders 71 and 72 and outputs it to the attenuator 76. The attenuator 76 attenuates the sub push-pull signal and outputs the attenuated signal to the inverting input terminal of the composite differential amplifier 77.

  The combined differential amplifier 77 generates a tracking error signal TE from the main push-pull signal attenuated by the attenuator 75 and the sub push-pull signal attenuated by the attenuator 76.

  The optical disc apparatus according to an embodiment of the present invention configured as described above performs the start-up operation shown in FIG. 5 when the optical disc 2 is inserted into the apparatus.

  When the starting operation shown in FIG. 5 is started, the spindle motor 52 first rotates the optical disc 2 (step S10), and then the DSP 32 obtains the number of recording layers of the optical disc by focus search (step S20).

  Next, the BEX motor 22 moves the collimating lens 17 using the set value for L0 measured in advance in the manufacturing process of the apparatus to correct the spherical aberration (step S30), and then the DSP 32 automatically outputs the focus error signal. The gain control is turned on (step S40), the focus control is drawn into the recording layer L0 farthest from the laser beam incident side, and the focus control is turned on (step S50).

  Then, the DSP 32 performs coarse adjustment of spherical aberration correction using the tracking error signal as an index (step S60), and then turns on automatic gain control of the tracking error signal (step S70), pulls in tracking control, and performs tracking control. Is turned on (step S80). When the automatic gain control of the tracking error signal is in the ON state, the DSP 32 calculates the sum of the electric signals SA to SH output from the photodetector 20 so that the amplitude level of the tracking error signal becomes a predetermined level. The attenuation amount of the attenuators 75 and 76 is adjusted according to the change.

  After that, the DSP 32 performs fine adjustment of spherical aberration correction using the RF signal output from the RF amplifier 31 as an index (step S90), and performs focus control loop gain adjustment and tracking control loop gain adjustment (step S90). Steps S100 and S110).

  Thereafter, the DSP 32 determines whether or not there is a next recording layer, that is, whether or not there is a recording layer that has not been subjected to the various adjustments described above (step S120).

  If there is the next recording layer (the recording layer far from the side on which the laser beam is incident next to the recording layer on which various adjustments were performed immediately before) (YES in step S120), the DSP 32 turns off automatic gain control of the tracking error signal. After the BEX motor 22 moves the collimating lens 17 and corrects the spherical aberration with the setting value for the next recording layer measured in advance in the manufacturing process of the apparatus, the DSP 32 performs focus jump to the next recording layer. Thus, the optical pickup 1 is controlled via the driver 42 (step S130), and then the process proceeds to step S60.

  On the other hand, if there is no next recording layer (NO in step S120), the adjustment is completed for all the recording layers, and the activation is ended. Note that the recording layer setting values measured in advance in the manufacturing process of the device may be stored in advance in a nonvolatile memory built in the DSP 32, for example.

  By the start-up operation as described above, rough adjustment for spherical aberration correction in all recording layers, including rough adjustment for spherical aberration correction at L0, is performed with the automatic gain control of the tracking error signal turned off.

  Therefore, during coarse adjustment of spherical aberration correction at start-up, an operation for correcting the amplitude change of the tracking error signal is added by automatic gain control of the tracking error signal, so that the actual amplitude of the tracking error signal is difficult to understand. There is no risk of becoming. As a result, it is possible to suppress variations in coarse adjustment of spherical aberration correction in the recording layers after L1 at the time of activation.

  Here, using BD-R_TL (three-layer write-once BD) compliant with the BDXL standard formulated in June 2010, the automatic gain control of tracking error signals is turned off in all recording layers L0 to L2, and collimation is performed. FIG. 6 shows the result of measuring the relationship between the movement amount of the lens 17 from the reference position and the amplitude levels of the RF signal and tracking error signal.

  Also, using the same BD-R_TL (three-layer write-once type BD) as described above, the automatic gain control of the tracking error signal is turned off in the recording layer L0, and the automatic gain control of the tracking error signal is performed in the recording layers L1 and L2. 7 shows the result of measuring the relationship between the amount of movement of the collimating lens 17 from the reference position and the amplitude level of the RF signal and tracking error signal.

  In FIG. 6 and FIG. 7, the characteristic line by the black circle plot shows the relationship between the amount of movement of the collimating lens 17 from the reference position in the recording layer L0 and the amplitude level of the tracking error signal, and the characteristic by the white circle plot. The line indicates the relationship between the amount of movement of the collimating lens 17 from the reference position in the recording layer L0 and the amplitude level of the RF signal. In FIG. 6 and FIG. 7, the characteristic line by the black triangle plot shows the relationship between the amount of movement of the collimating lens 17 from the reference position in the recording layer L1 and the amplitude level of the tracking error signal. The characteristic line by the plot of (2) shows the relationship between the amount of movement of the collimating lens 17 from the reference position in the recording layer L1 and the amplitude level of the RF signal. In FIG. 6 and FIG. 7, the characteristic line by the black square plot shows the relationship between the amount of movement of the collimating lens 17 from the reference position in the recording layer L2 and the amplitude level of the tracking error signal. The characteristic line by the plot of (2) shows the relationship between the amount of movement of the collimating lens 17 from the reference position in the recording layer L2 and the amplitude level of the RF signal. In each characteristic line, the maximum value of the amplitude level of the RF signal or tracking error signal is set to 0 [dB].

  The measurement results in FIG. 6 correspond to rough adjustment and fine adjustment of spherical aberration correction at the time of start-up in the optical disc apparatus according to one embodiment of the present invention, and any characteristic line indicates the RF signal or tracking error signal. The peak of the amplitude level is clear. For this reason, in the optical disc apparatus according to an embodiment of the present invention, the adjustment using the tracking error signal at the time of activation as an index is less varied as in the other adjustments at the time of activation.

  The measurement result of FIG. 7 corresponds to rough adjustment and fine adjustment of spherical aberration correction at the start-up of the conventional optical disc apparatus, and a characteristic line (a reference of the collimating lens 17 in the recording layer L1) by a black triangle plot. Characteristic line indicating the relationship between the amount of movement from the position and the amplitude level of the tracking error signal) and a characteristic line by plotting a black square (the amount of movement of the collimating lens 17 from the reference position in the recording layer L2 and the amplitude of the tracking error signal). In the characteristic line showing the relationship with the level, the peak of the amplitude level of the tracking error signal is not clear. For this reason, in the conventional optical disc apparatus, variation in adjustment using the tracking error signal at the time of activation as an index becomes large.

  In this embodiment, as a representative example of the adjustment using the tracking error signal at the time of activation as an index, rough adjustment of spherical aberration correction at the time of activation is taken up. However, the present invention is not limited to this. That is, the present invention may be applied by performing adjustment using the tracking error signal at the start as an index other than the rough adjustment of spherical aberration correction at the start.

  In the present embodiment, the measurement is performed on the BD-R_TL. However, the optical disc apparatus according to the present invention is a single-sided multilayer optical disc (for example, a dual-layer DVD, a dual-layer BD, or a BDXL) other than the write-once BD conforming to the BDXL standard. It may be compatible with a rewritable BD conforming to a standard).

DESCRIPTION OF SYMBOLS 1 Optical pick-up 2 Optical disk 10a 1st light source 10b 2nd light source 11a 1st grating 11b 2nd grating 12 Dichro prism 13 Collimating lens 14 Beam splitter 15 Rising mirror 16 1/4 wavelength plate 17 Collimating lens 18 Objective lens 19 Detection lens 20 Optical detector 21 Actuator 22 BEX motor 31 RF amplifier 32 DSP
33 Reproduction processing circuit 34 Output circuit 41 CPU
42 Driver 43 Display Unit 44 Operation Unit 51 Feed Motor 52 Spindle Motor 61-68 Variable Gain Amplifier 69-72 Adder 73 Main Differential Amplifier 74 Sub Differential Amplifier 75, 76 Attenuator 77 Synthetic Differential Amplifier

Claims (3)

An optical disc apparatus capable of supporting a single-sided multilayer optical disc having a plurality of recording layers on one side,
An optical pickup for irradiating the optical disc with light and detecting the return light from the optical disc with a photodetector;
Tracking error signal generating means for processing the electrical signal output from the photodetector to generate a tracking error signal;
Automatic gain control means for performing automatic gain control of the tracking error signal so that the amplitude level of the tracking error signal becomes a predetermined level;
Adjustment means for performing adjustment using the tracking error signal as an index when the optical disk device is activated,
When the adjustment means performs adjustment using the tracking error signal as an index when starting the optical disk apparatus, the automatic gain control of the tracking error signal by the automatic gain control means is turned off in the adjustment for all recording layers of the optical disk. An optical disc apparatus characterized by being in a state.   The adjusting means has movable lens position adjusting means for adjusting and controlling the position of a spherical aberration correcting movable lens disposed in the optical system of the optical pickup, and the tracking error signal is used as an index when the optical disk device is started. 2. The optical disk apparatus according to claim 1, wherein the position of the spherical aberration correcting movable lens is coarsely adjusted using the movable lens position adjusting means.   The optical disc apparatus according to claim 1, wherein the optical disc apparatus is compatible with a BD conforming to the BDXL standard.

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