JP4788071B2 - Optical pickup and recording / reproducing apparatus - Google Patents

Optical pickup and recording / reproducing apparatus Download PDF

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Publication number
JP4788071B2
JP4788071B2 JP2001197886A JP2001197886A JP4788071B2 JP 4788071 B2 JP4788071 B2 JP 4788071B2 JP 2001197886 A JP2001197886 A JP 2001197886A JP 2001197886 A JP2001197886 A JP 2001197886A JP 4788071 B2 JP4788071 B2 JP 4788071B2
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Japan
Prior art keywords
recording
optical
correction
state
spherical aberration
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JP2003016660A (en
Inventor
功 市村
清志 真能
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ソニー株式会社
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Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical pickup and a recording / reproducing apparatus for performing various signal recordings and signal reproductions on an optical recording medium having a plurality of recording layers.
[0002]
[Prior art]
Conventionally, it has been known that in an optical disk recording / reproducing apparatus using an objective lens having a high numerical aperture (NA), spherical aberration due to a thickness error of a light transmission layer is remarkable.
For example, taking a recording / reproducing system having a recording / reproducing light source wavelength λ = 400 nm and NA = 0.85 as an example, the accuracy of the disk substrate thickness is required to be ± 4 μm or less.
On the other hand, as a technology for doubling the recording capacity per optical disc using the same optical system, development of a double-layer disc in which two recording layers are made multi-layered is in progress. In order to avoid signal interference between the two recording layers, it is considered necessary to ensure an interlayer distance of each recording layer of at least about 20 μm.
However, since the value of 20 μm is larger than the thickness accuracy (± 4 μm) required for the above-described disk substrate, a high-quality signal can be recorded and reproduced for both recording layers using the same optical system. There is a problem that can not be.
[0003]
[Problems to be solved by the invention]
Therefore, for such a problem, for example, spherical aberration correction of an expander lens (for example, see Japanese Patent Laid-Open No. 2000-131603) or a liquid crystal element (for example, see Japanese Patent Laid-Open No. 10-269611) composed of two lens groups. By using the optical unit for the optical pickup, when the focus servo of the optical pickup is pulled in, the correction state of the optical unit is controlled so that the spherical aberration is properly corrected for the recording layer to be focused in advance. Thus, a method for stabilizing the pull-in is proposed.
[0004]
Further, in this proposal, the following two controls are adopted as operations when the light spot moves between two recording layers (focus jump).
(1) As in the case of focus pull-in, the state of the optical unit is maintained so that spherical aberration is favorably corrected with respect to a recording layer (hereinafter referred to as a target recording layer) to which a focus jump is performed in advance. .
(2) The state of the optical unit is maintained so that spherical aberration is favorably corrected with respect to the intermediate layer between the currently focused recording layer and the target recording layer.
By such a method, a focus jump operation is realized by obtaining a good focus error signal.
[0005]
However, when the method (1) is used, the current focus servo may be lost when controlling the state of the optical unit so that spherical aberration is satisfactorily corrected with respect to the target recording layer in advance. .
Further, when the method (2) is used, the current focus servo is not lost, but when the reflectance of the target recording layer is low or when the signal is noisy due to interlayer interference or the like, the light spot is The phenomenon of not being drawn on the target recording layer occurs.
[0006]
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an optical pickup and a recording / reproducing apparatus capable of stably performing a focus jump of an optical spot on an optical recording medium having a plurality of recording layers.
[0007]
[Means for Solving the Problems]
  In order to achieve the above object, a first aspect of the present invention is provided in a recording / reproducing apparatus that performs at least one of recording and reproduction with respect to an optical recording medium having a plurality of recording layers. In an optical pickup provided with an optical unit that corrects or a recording / reproducing apparatus having the optical pickup, the optical pickup includes a correction state control unit that controls a correction state of spherical aberration in the optical unit, and the correction state control unit includes: Before starting a focus jump operation for jumping from a focus adjusted to one recording layer to a focus adjusted to another recording layer in the optical recording medium,With the focus servo not released,The correction state of the optical unit is an intermediate state between an optimum state Sc for spherical aberration correction corresponding to the certain recording layer and an optimum state Sd for spherical aberration correction corresponding to the other recording layer, and Control is performed so that the optimum state Sd of spherical aberration correction corresponding to another recording layer is held in a state Sd ′ closer to the optimum state.
[0008]
  According to a second aspect of the present invention, there is provided a recording / reproducing apparatus that performs at least one of recording and reproduction with respect to an optical recording medium having a plurality of recording layers, and includes an optical unit that corrects spherical aberration inside the optical system. A pickup, or a recording / reproducing apparatus having the optical pickup, having a correction state control means for controlling a correction state of spherical aberration in the optical unit;A function of storing a time required for a focus jump operation for jumping from a focus adjusted to a certain recording layer in the optical recording medium to a focus adjusted to another recording layer;The correction state control means includesFocus jump operationSimultaneously with the start of the correction, the correction state change control in the optical unit is started, and at the end of the focus jump operation, the correction state of the optical unit is set to the optimum state Sd of spherical aberration correction corresponding to the other recording layer. In this case, control is performed so as to be held within a predetermined range Sd ± ΔSd.
[0009]
  According to a third aspect of the present invention, there is provided a recording / reproducing apparatus that performs at least one of recording and reproduction with respect to an optical recording medium having a plurality of recording layers, and includes an optical unit that corrects spherical aberration inside the optical system. A pickup, or a recording / reproducing apparatus having the optical pickup, having a correction state control means for controlling a correction state of spherical aberration in the optical unit;A function of storing a time required for a focus jump operation for jumping from a focus adjusted to a certain recording layer in the optical recording medium to a focus adjusted to another recording layer;The correction state control means includesFocus jump operationBefore starting the control, change control of the correction state in the optical unit is started, the state of the optical unit is the optimal state Sc for spherical aberration correction corresponding to the certain recording layer, and the spherical aberration correction corresponding to the other recording layer The focus jump operation starts when a predetermined correction state Sm intermediate to the optimum state Sd is reached, and further, at the end of the focus jump operation, the correction state of the optical unit is changed to the other recording layer. Control is performed such that the corresponding spherical aberration correction optimum state Sd is maintained within a predetermined range Sd ± ΔSd.
[0011]
  In the optical pickup and recording / reproducing apparatus according to the first invention described above, Sc is the optimum state of spherical aberration correction corresponding to a recording layer currently focused on the optical recording medium, and another recording layer (target When the optimum state of spherical aberration correction corresponding to the recording layer is Sd, before starting the focus jump operation,With the focus servo not released,The correction state of the optical unit is an intermediate state between the optimum state Sc for spherical aberration correction corresponding to the current recording layer and the optimum state Sd for spherical aberration correction corresponding to the target recording layer, and the other recording layer. The spherical aberration correction optimum state Sd corresponding to is controlled in advance so as to be held in a state Sd ′ closer.
  Thereby, the current focus servo can be performed without fail, and the focus pull-in operation with respect to the target recording layer can be performed reliably, and the focus jump can be performed stably.
[0012]
  Further, in the optical pickup and recording / reproducing apparatus according to the second invention, simultaneously with the start of the focus jump operation, the correction state change control in the optical unit is started,At the end of the focus jump operationIn addition, the correction state of the optical unit is a predetermined range with respect to the optimum state Sd of spherical aberration correction corresponding to the target recording layer.Sd ± ΔSdIt was made to control so that it was hold | maintained.
  That is, since the state change of the optical unit is started simultaneously with the start of the focus jump, and at the end of the jump, the optical unit can be controlled to a state in which the spherical aberration is well corrected with respect to the target recording layer. A focus pull-in operation with respect to the target recording layer can be performed reliably without deviating the current focus servo, and a focus jump can be performed stably.
  This method can be adopted when the spherical aberration correcting optical unit can change its state at the same speed as the focus jump operation.
[0013]
  In the optical pickup and recording / reproducing apparatus according to the third aspect of the invention, the control of changing the correction state in the optical unit is started before the focus jump operation is started, and the state of the optical unit corresponds to the current recording layer. When a predetermined correction state Sm intermediate between the optimal state Sc for correction and the optimal state Sd for spherical aberration correction corresponding to the target recording layer is reached, a focus jump operation is started.At the end of the focus jump operationIn addition, the correction state of the optical unit is a predetermined range with respect to the optimum state Sd of spherical aberration correction corresponding to the target recording layer.Sd ± ΔSdIt was made to control so that it was hold | maintained.
[0014]
In the third invention, the slow correction speed of the optical unit for correcting spherical aberration is compensated by combining the first and second inventions described above. That is, the state change of the optical unit for correcting spherical aberration is started first, and the focus jump operation is started with a slight delay. At the end of the jump, as in the second invention, the spherical aberration correcting optical unit is controlled so as to have a range in which the spherical aberration is favorably corrected with respect to the target recording layer.
As a result, even when the optical unit for correcting spherical aberration cannot change its state at the same speed as the focus jump operation, the current focus servo is not deviated and the focus pull-in operation for the target recording layer can be performed reliably. The focus jump can be performed stably.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of an optical pickup and a recording / reproducing apparatus according to the present invention will be described.
The embodiments described below are preferred specific examples of the present invention, and various technically preferable limitations are given. However, the scope of the present invention is not limited to the following description. Unless otherwise specified, the present invention is not limited to these embodiments.
The recording / reproducing apparatus according to the present invention means an apparatus such as a disk drive that performs at least one of recording and reproduction of information with respect to an optical recording medium. And a device that performs both recording and reproduction.
[0017]
An optical pickup and recording / reproducing apparatus according to an embodiment of the present invention records and reproduces information with respect to a multi-layer disc having a plurality of recording layers, and is an expander lens (for example, a special lens) composed of two lens groups. By using an optical unit for correcting spherical aberration such as a liquid crystal element (see, for example, Japanese Patent Laid-Open No. 10-269611), the focus is adjusted in advance when the focus servo of the optical pickup is drawn. The optical recording unit is configured to control the correction state of the optical unit and stabilize the pull-in so that the spherical aberration can be corrected satisfactorily.
Then, in the focus jump operation in which the focus is pulled in by moving to another recording layer (target recording layer) from the state in which the recording layer of the multi-layer disc is focused, the spherical aberration is corrected by the following method. The focus jump is stably performed by controlling the optical unit.
[0018]
  (1) Before starting the focus jump, the spherical aberration correcting optical unit is maintained in a state in which the spherical aberration is corrected with respect to the target recording layer as much as possible within the range where the current focus servo is not removed (first). Invention).
  (2) Focus jumpSimultaneously with the startThe change in state of the optical unit for correcting spherical aberration is started, and at the end of the jump, the optical unit for correcting spherical aberration is held in a state where the spherical aberration is corrected well with respect to the target recording layer (first) Invention of 2). However, this method can be employed only when the spherical aberration correcting optical unit can change its state at the same speed as the focus jump operation.
[0019]
  (3) The slowness of the correction speed of the spherical aberration correcting optical unit is compensated for by the method combining (1) and (2) above. That is, the state change of the optical unit for correcting spherical aberration is started before the focus jump operation, and the focus jump operation is started with a slight delay. Then, at the end of the focus jump operation, the spherical aberration correcting optical unit is held in a range in which the spherical aberration is corrected well with respect to the target recording layer, as in (2) above.(Third invention).
[0020]
Hereinafter, specific examples to which the present embodiment is applied will be described in detail with reference to the drawings.
FIG. 1 is a block diagram showing the overall configuration of the recording / reproducing apparatus according to the present embodiment, and FIG. 2 is a cross-sectional view showing the configuration of the optical system of the optical pickup included in the recording / reproducing apparatus shown in FIG. is there.
As shown in FIG. 1, the recording / reproducing apparatus includes a disk drive system 40 that rotationally drives an optical disk 30, an optical pickup 50 that performs signal recording and reproduction operations on the optical disk 30, a disk drive system 40, and And a servo control system 60 for controlling the optical pickup 50.
The disk drive system 40 includes a spindle motor 41 for rotationally driving the optical disk 30 and a disk clamp 42 provided on the spindle of the spindle motor 41, and is controlled by a spindle driver 61 provided in the servo control system 60. Then, the optical disk is rotationally driven at a predetermined rotational speed.
[0021]
The optical pickup 50 also holds an objective lens 51 for the optical disk 30 and performs a biaxial actuator 52 for performing focus servo and tracking servo of the light spot, a laser diode (LD) 53 for emitting laser light, and reflection from the optical disk. A light detector (PD) 54 for detecting light, an optical system block 55 for guiding laser light to the optical disk 30 and for guiding reflected light from the optical disk to the light detector (PD) 54, and this optical system block 55 It has a moving mechanism 57 including a moving slide motor 56, an LD driver 58 that drives a laser diode (LD) 53, and an expander 59 that is an optical unit for correcting spherical aberration.
The state of the expander 59 is detected by the expander position sensor 59A.
[0022]
The servo control system 60 also drives the spindle driver 61 that outputs a drive signal for the spindle motor 41, the expander driver 62 that outputs a control signal for controlling the state of the expander 59, and the focusing coil in the biaxial actuator 52. A focus driver 63 that outputs a signal, a tracking driver 64 that outputs a drive signal for driving the tracking coil, a slide motor driver 65 that outputs a drive signal for the slide motor 56, and an LD driver 58 for controlling the output of the LD 53 And an envelope detection circuit 67 for detecting the amplitude of the RF signal, which is an information signal recorded on the optical disc 30 based on the detection signal from the photodetector (PD) 54, and the detection from the photodetector (PD) 54. Generate various servo signals based on the signal That has a servo matrix substrate 68, a conversion unit 69 for performing A / D conversion and the like of various data, and a control microcomputer 66 and DSP70 controls the operation of the entire control system.
In this example, the expander position signal output from the expander position sensor 59A is A / D converted together with the RF amplitude signal, the focus error signal, the sum signal, and the tracking error signal, and the DSP 70 uses these signals. Is in charge of each servo control.
[0023]
Further, as shown in FIG. 2, the optical system block 55 includes a grating lens 551, a polarization beam splitter 552, a collimator lens 553, a quarter wavelength plate 554, and a multi lens 555.
In this example, the objective lens 51 is constituted by a two-group lens including a condenser lens (first objective lens) 511 and a SIL (Solid Immersion Lens = second objective lens) 512, and a high NA objective lens is used. It is configured to record and reproduce signals.
The expander 59 includes a two-group lens including a first correction lens 591 and a second correction lens 592, and an expander drive actuator 593 that drives the second correction lens 592 to change the correction state.
That is, in this optical system, an expander lens group is arranged in front of the objective lens 51, the first correction lens 591 is fixed, and the second correction lens 592 is displaced in the optical axis direction by the expander drive actuator 593. Spherical aberration correction is realized.
[0024]
Laser light emitted from the laser diode (LD) 53 is supplied to the optical disc 30 through the grating lens 551, the polarizing beam splitter 552, the collimator lens 553, the quarter wavelength plate 554, the expander 59, and the objective lens 51.
The return light from the optical disk 30 is guided to the photodetector (PD) 54 through the objective lens 51, the expander 59, the quarter wavelength plate 554, the collimator lens 553, the polarization beam splitter 552, and the multi lens 555.
The signal detected by the photodetector (PD) 54 is sent to a servo matrix substrate 68, where a focus error signal, a sum signal, and a tracking error signal are generated, A / D converted, and then input to the DSP 70. Is done.
The main spot signal is processed by the envelope detection circuit 67, output as an RF amplitude signal, A / D converted, and then input to the DSP.
[0025]
FIG. 3 is a block diagram showing a configuration of internal processing of the DSP 70. Note that branching processing such as condition determination is omitted.
The above-described focus error signal and tracking error signal are phase compensated (71A, 71B) inside the DSP 70 and output to the focus driver 63 and the tracking driver 64, respectively. The focus driver 63 outputs a phase-compensated focus error signal at the timing when the focus on determination (74) is made based on the focus error signal and the sum signal.
The slide motor driver 65 outputs a signal in which the low frequency of the tracking error signal is emphasized by the low frequency emphasizing filter (72).
For the expander 59, during normal signal reproduction, the expander position target value is determined so that the RF amplitude value is maximized, the difference between the value and the current position is phase compensated (71C), and the expander driver 62 Output.
However, at the time of focus pull-in or focus jump, control is performed so as to follow the position target value (73) of the expander called from the memory 75 as described later.
[0026]
FIG. 4 is a cross-sectional view showing the configuration of the expander drive actuator 593 used in this example.
The second correction lens 592 is attached to the lens holder 81, and is attached to the main body 50A of the optical pickup 50 via two spiral springs 82 arranged in parallel.
A drive coil 83 is attached to the side surface of the lens holder 81 and is disposed in a magnetic circuit (yoke 84 and magnet 85) provided on the fixed portion (optical pickup body 50A) side. A current is supplied to the drive coil 83. By applying this, a driving force for driving the lens 592 in the optical axis direction (vertical direction in the figure) is generated.
At both ends of the lens holder 81 in the optical axis direction, stoppers 861 and 862 for restricting excessive movement of the second correction lens 592 in the optical axis direction are provided so as to protrude from the optical pickup main body 50A toward the optical axis. It has been.
[0027]
Further, a notch 862A is provided on a part of the circumference of the stopper 862, and a reflection plate 87 for reflecting the LED light emitted from the position detection sensor 59A is a lens in the notch 862A. It is attached to the holder 81 and arranged.
On the other hand, on the optical pickup main body 50A side, a position detection sensor 59A is provided at a position facing the reflecting plate 87. This position detection sensor 59A has a built-in reflection type optical distance sensor that is a combination of a light emitting element (LED) and a light receiving element, and detects the LED light reflected by the reflecting plate 87. The position in the optical axis direction is detected.
[0028]
FIG. 5A is an explanatory diagram showing the operation of the objective lens and the spherical aberration correcting lens unit (expander lens) according to the first embodiment of the present invention. The vertical axis indicates the focal position (solid line) of the objective lens and the expander. The position of the lens (broken line) is shown, and the horizontal axis shows time. The first embodiment corresponds to the contents of the first invention described above.
In the present embodiment, before the focus jump is started, the second correction lens 592 of the expander 59 is at an intermediate position between the optimum position Pc corresponding to the current recording layer and the optimum position Pd corresponding to the target recording layer. Pre-positioned at a position Pd ′ that is closer to the optimum position Pd.
As a method of selecting the position Pd ′, it is preferable to select a position where the spherical aberration is favorably corrected with respect to the target recording layer as much as possible within a range where the current focus servo does not deviate.
[0029]
As can be seen from FIG. 5 (b), once the focus servo is applied, the servo is less likely to come off even if there is some spherical aberration. On the other hand, when the focus is pulled in, a stable S curve cannot be obtained. Therefore, the position Pd ′ is an intermediate position between the position Pc and the position Pd, and a position closer to the position Pd is appropriate.
After the focus jump, the expander second correction lens 592 is positioned until it reaches the position Pd (post-process).
In this embodiment, since the operations of the expander lens and the objective lens are completely independent, the moving speed of the expander lens can be arbitrarily selected.
[0030]
FIG. 6 is an explanatory view showing the operation of the objective lens and the spherical aberration correcting lens unit (expander lens) according to the second embodiment of the present invention, and the vertical axis indicates the focal position (solid line) of the objective lens and the position of the expander lens. (Dashed line) is shown, and the horizontal axis shows time. The second embodiment corresponds to the contents of the second invention described above.
In this embodiment, the movement of the second correction lens 592 of the expander is started almost simultaneously with the start of the focus jump operation, and at the end of the focus jump, the second correction lens 592 is positioned in the range of position Pd ± ΔPd.
Here, ΔPd is a value that is determined in consideration of a margin from the control performance of the expander 59 and the time stability of the focus jump, and is as small as possible in order to pull the focus sufficiently stably on the target recording layer. It is desirable to be a value.
In this method, even after the focus jump, the second correction lens 592 is continuously moved and positioned until it reaches Pd.
This method is the most ideal because the focus jump is always performed in a state where the spherical aberration is well corrected. However, the second correction lens 592 of the expander 59 corrects the spherical aberration within the same time as the focus jump operation. It can be adopted only when possible.
[0031]
FIG. 7 is an explanatory diagram showing the operation of the objective lens and the spherical aberration correcting lens unit (expander lens) according to the third embodiment of the present invention, and the vertical axis indicates the focal position (solid line) of the objective lens and the position of the expander lens. (Dashed line) is shown, and the horizontal axis shows time. The third embodiment corresponds to the contents of the third invention described above.
In this embodiment, the first embodiment and the second embodiment described above are combined, and it is a countermeasure when the speed of spherical aberration correction by the second correction lens 592 is slow compared to the focus jump operation. is there.
First, the second correction lens 592 is driven to a predetermined position Pm, and a focus jump is started at that time.
Thereafter, as in the second embodiment, at the end of the focus jump, the second correction lens 592 is positioned in the range of Pd ± ΔPd. Here, an arbitrary position from Pc to Pd ′ is selected as Pm. However, the closer to Pc, the harder the focus before jumping is, and the closer to Pd ′, the slower the moving speed of the second correction lens 592 may be.
[0032]
In the example of FIG. 7, the second correction lens 592 is temporarily stopped at Pm, but it may pass through Pm as it is toward Pd.
Further, in a multi-layer disc having three or more recording layers, when jumping to a recording layer that is not adjacent, the operation of any of the first, second, and third embodiments described above is performed on the adjacent recording layer. By repeating this step, a jump to a separate recording layer is performed. In this way, a more stable jump operation can be realized than when jumping at once.
In the second and third embodiments, a function for storing the time taken for the focus jump operation up to the previous time is provided, so that the second and subsequent focus jump operations are based on the stored values. The moving speed of the correction lens 592 may be recalculated.
[0033]
FIG. 8 is an explanatory diagram showing the state of the control operation of the expander 59 when such a control example is applied to the second embodiment. The vertical axis indicates the speed of the expander lens (solid line) and the position of the expander lens (broken line). ) And the horizontal axis indicates time.
At the time of the first focus jump, the jump time Δt previously stored in the memoryfjIs used, and for the second and subsequent jumps, ΔtfjOr past average value △ tfj-aveIs used to determine the moving speed of the expander.
Further, the position target value at each time is calculated from the speed target value and set as the target value of the expander control loop.
In this example, the bang-bang control is used, but a trapezoidal control or the like may be used. In this embodiment, the position control system is configured, but speed control may be performed instead of position control.
[0034]
  FIG.Reference examples for the present inventionIs an explanatory view showing the operation of the objective lens and the spherical aberration correcting lens unit (expander lens) by the vertical axis, the vertical axis indicates the focal position of the objective lens (solid line) and the position of the expander lens (dashed line), and the horizontal axis indicates time. Show. The fourth embodiment corresponds to the contents of the fourth invention described above.
  This exampleThen, when the focal position moving operation is started, the second correction lens 592 starts to move toward the optimum position Pd corresponding to the target recording layer.
  On the other hand, the focus servo is stopped on the objective lens 51 side, and once it is retracted in the direction away from the disk 30, it approaches the disk 30 again, and the light spot is selectively focused on the target recording layer. When this focus pull-in operation is performed, the second correction lens 592 is already positioned at the optimum position Pd.
[0035]
Further, in order to selectively focus the light spot on the target recording layer, the number of peaks of the sum signal when the objective lens 51 is approaching the disc is detected, and the sum after the detection of the predetermined number of peaks is completed. Pulling in is performed by the signal level and the focus error zero cross.
FIG. 10 is an explanatory diagram showing the position of the focus drive signal, the sum signal, the focus error signal, and the light spot when selectively focusing on the innermost recording layer of the three-layer disc.
[0036]
In any of the embodiments described above, after the focus jump is completed and the expander reaches the optimum position Pd, the expander position is adjusted so that the amplitude of the tracking error signal and the amplitude of the reproduction RF signal are maximized. Adjust to further optimize spherical aberration correction.
In each of the above-described embodiments, an expander lens is used to correct spherical aberration. However, the present invention is not limited to this, and for example, a liquid crystal element, a collimator lens, or the like is driven. Correction may be performed by the following.
For example, when a liquid crystal element is used in an optical unit for correcting spherical aberration, a configuration as disclosed in Japanese Patent Laid-Open No. 10-269611 can be applied.
[0037]
【The invention's effect】
  As described above, in the optical pickup and the recording / reproducing apparatus of the present invention, Sc is the optimum state of spherical aberration correction corresponding to a recording layer that is currently focused on the optical recording medium, and other recording layers that perform focus jump ( When the optimal state of spherical aberration correction corresponding to the target recording layer is Sd, before starting the focus jump operation,With the focus servo not released,The correction state of the optical unit is an intermediate state between the optimum state Sc for spherical aberration correction corresponding to the current recording layer and the optimum state Sd for spherical aberration correction corresponding to the target recording layer, and the other recording layer. The spherical aberration correction optimum state Sd corresponding to is controlled in advance so as to be held in a state Sd ′ closer.
  Thereby, the current focus servo can be performed without fail, and the focus pull-in operation with respect to the target recording layer can be performed reliably, and the focus jump can be performed stably.
  In particular, in a recording / reproducing apparatus using a high NA objective lens, there is an effect that the focus servo can be surely drawn after the jump by performing the focus jump while correcting the spherical aberration.
[0038]
  In the optical pickup and recording / reproducing apparatus of the present invention, the control of changing the correction state in the optical unit is started simultaneously with the start of the focus jump operation,At the end of the focus jump operationIn addition, the correction state of the optical unit is a predetermined range with respect to the optimum state Sd of spherical aberration correction corresponding to the target recording layer.Sd ± ΔSdIt was made to control so that it was hold | maintained.
  Thereby, the current focus servo can be performed without fail, and the focus pull-in operation with respect to the target recording layer can be performed reliably, and the focus jump can be performed stably.
  In particular, in a recording / reproducing apparatus using a high NA objective lens, there is an effect that the focus servo can be surely drawn after the jump by performing the focus jump while correcting the spherical aberration.
  This method can be adopted when the spherical aberration correcting optical unit can change its state at the same speed as the focus jump operation.
[0039]
  In the optical pickup and recording / reproducing apparatus of the present invention, the control of changing the correction state in the optical unit is started before the focus jump operation is started, and the state of the optical unit is used to correct spherical aberration corresponding to the current recording layer. When a predetermined correction state Sm intermediate between the optimal state Sc and the optimal state Sd of spherical aberration correction corresponding to the target recording layer is reached, a focus jump operation is started.At the end of the focus jump operationIn addition, the correction state of the optical unit is a predetermined range with respect to the optimum state Sd of spherical aberration correction corresponding to the target recording layer.Sd ± ΔSdIt was made to control so that it was hold | maintained.
  As a result, even when the optical unit for correcting spherical aberration cannot change its state at the same speed as the focus jump operation, the current focus servo is not deviated and the focus pull-in operation for the target recording layer can be performed reliably. The focus jump can be performed stably.
  In particular, in a recording / reproducing apparatus using a high NA objective lens, there is an effect that the focus servo can be surely drawn after the jump by performing the focus jump while correcting the spherical aberration.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an overall configuration of a recording / reproducing apparatus according to an embodiment of the present invention.
2 is a cross-sectional view showing a configuration of an optical system of an optical pickup included in the recording / reproducing apparatus shown in FIG.
3 is a block diagram showing a configuration of internal processing of a DSP included in the recording / reproducing apparatus shown in FIG.
4 is a cross-sectional view showing a configuration of an expander drive actuator included in the recording / reproducing apparatus shown in FIG.
FIG. 5 is an explanatory diagram showing operations of the objective lens and the spherical aberration correcting lens unit according to the first embodiment of the present invention.
FIG. 6 is an explanatory diagram showing the operation of the objective lens and the spherical aberration correcting lens unit according to the second embodiment of the present invention.
FIG. 7 is an explanatory diagram showing operations of an objective lens and a spherical aberration correcting lens unit according to a third embodiment of the present invention.
FIG. 8 is an explanatory diagram showing a position control operation of a spherical aberration correcting lens unit according to the second embodiment of the present invention.
FIG. 9Reference examples for the present inventionIt is explanatory drawing which shows the focus position moving operation by.
FIG. 10Reference examples for the present invention4 is an explanatory diagram showing the position of a focus drive signal, a sum signal, a focus error signal, and a light spot when selectively focusing on the innermost recording layer of the three-layer disc.
[Explanation of symbols]
30 ... Optical disk, 40 ... Disk drive system, 41 ... Spindle motor, 42 ... Disk clamp, 50 ... Optical pickup, 51 ... Objective lens, 52 ... Biaxial actuator, 53 ... Laser diode (LD) ), 54... Photodetector (PD), 55... Optical system block, 56... Slide motor, 57... Moving mechanism, 58 .. LD driver, 59 ... Expander, 59 A ... Expander position sensor, 60 ... Servo control system, 61 ... Spindle driver, 62 ... Expander driver, 63 ... Focus driver, 64 ... Tracking driver, 65 ... Slide motor driver, 66 ... Control microcomputer, 67 ... Envelope detection Circuit 68. Servo matrix substrate 69 69 Memory 70 DSP

Claims (18)

  1. In an optical pickup provided in a recording / reproducing apparatus that performs at least one of recording and reproduction with respect to an optical recording medium having a plurality of recording layers, and having an optical unit that corrects spherical aberration inside the optical system,
    Correction state control means for controlling the correction state of spherical aberration in the optical unit;
    The correction state control means is in a state where the focus servo is not removed before starting a focus jump operation for jumping from a focus adjusted to a certain recording layer to a focus adjusted to another recording layer in the optical recording medium,
    The correction state of the optical unit is an intermediate state between an optimum state Sc for spherical aberration correction corresponding to the certain recording layer and an optimum state Sd for spherical aberration correction corresponding to the other recording layer, and Control is performed so as to preliminarily maintain a state Sd ′ closer to the optimum state Sd of spherical aberration correction corresponding to the other recording layers.
    Optical pickup.
  2.   2. The optical pickup according to claim 1, wherein after the focus jump operation is performed, the correction state of the optical unit is controlled to a spherical aberration correction unit optimum state Sd corresponding to the other recording layer.
  3.   The optical recording medium has three or more recording layers, and at the time of a focus jump operation between non-adjacent recording layers, the operation of the correction state control unit is repeatedly performed on the adjacent recording layers, thereby the optical unit. The optical pickup according to claim 1, wherein the correction state is optimized.
  4.   2. The optical pickup according to claim 1, wherein each data used by the correction state control means for controlling the optical unit is read out from data stored in a memory in advance.
  5.   2. The optical pickup according to claim 1, wherein after the focus jump operation is finished, reflected light from the optical recording medium is detected by a light receiving element, and spherical aberration correction is further optimized while observing the detection signal. .
  6. In an optical pickup provided in a recording / reproducing apparatus that performs at least one of recording and reproduction with respect to an optical recording medium having a plurality of recording layers, and having an optical unit that corrects spherical aberration inside the optical system,
    Correction state control means for controlling the correction state of spherical aberration in the optical unit;
    A function of storing a time required for a focus jump operation for jumping from a focus adjusted to a certain recording layer in the optical recording medium to a focus adjusted to another recording layer;
    The correction state control means starts the correction state change control in the optical unit simultaneously with the start of the focus jump operation ,
    At the end of the focus jump operation, control is performed so that the correction state of the optical unit is held within a predetermined range Sd ± ΔSd with respect to the optimum state Sd of spherical aberration correction corresponding to the other recording layer. ,
    Optical pickup.
  7. 7. The optical pickup according to claim 6 , wherein the correction state changing speed by the correction state control means is controlled based on a predetermined reference time value or a focus jump operation time value stored in a memory until the previous time.
  8. In an optical pickup provided in a recording / reproducing apparatus that performs at least one of recording and reproduction with respect to an optical recording medium having a plurality of recording layers, and having an optical unit that corrects spherical aberration inside the optical system,
    Correction state control means for controlling the correction state of spherical aberration in the optical unit;
    A function of storing a time required for a focus jump operation for jumping from a focus adjusted to a certain recording layer in the optical recording medium to a focus adjusted to another recording layer;
    The correction state control means starts control for changing the correction state in the optical unit before starting the focus jump operation ,
    The state of the optical unit has reached a predetermined correction state Sm intermediate between the optimal state Sc of spherical aberration correction corresponding to the certain recording layer and the optimal state Sd of spherical aberration correction corresponding to the other recording layer. Sometimes start the focus jump action,
    Further, at the end of the focus jump operation, the correction state of the optical unit is held within a predetermined range Sd ± ΔSd with respect to the optimum spherical aberration correction state Sd corresponding to the other recording layer. Control,
    Optical pickup.
  9. 9. The optical pickup according to claim 8 , wherein the correction state changing speed by the correction state control means is controlled based on a predetermined reference time value or a focus jump operation time value stored in a memory until the previous time.
  10. In a recording / reproducing apparatus having an optical pickup provided with an optical unit for correcting spherical aberration in an optical system and performing at least one of recording and reproduction on an optical recording medium having a plurality of recording layers.
    Correction state control means for controlling the correction state of spherical aberration in the optical unit;
    The correction state control means is in a state where the focus servo is not removed before starting a focus jump operation for jumping from a focus adjusted to a certain recording layer to a focus adjusted to another recording layer in the optical recording medium,
    The correction state of the optical unit is an intermediate state between an optimum state Sc for spherical aberration correction corresponding to the certain recording layer and an optimum state Sd for spherical aberration correction corresponding to the other recording layer, and Control is performed so as to preliminarily maintain a state Sd ′ closer to the optimum state Sd of spherical aberration correction corresponding to the other recording layers.
    Recording / playback device.
  11. 11. The recording / reproducing apparatus according to claim 10 , wherein after the focus jump operation is performed, the correction state of the optical unit is controlled to a spherical aberration correction unit optimum state Sd corresponding to the other recording layer.
  12. The optical recording medium has three or more recording layers, and at the time of a focus jump operation between non-adjacent recording layers, the operation of the correction state control unit is repeatedly performed on the adjacent recording layers, thereby the optical unit. 11. The recording / reproducing apparatus according to claim 10 , wherein the correction state is optimized.
  13. 11. The recording / reproducing apparatus according to claim 10, wherein each data used by the correction state control means for controlling the optical unit is read out from data stored in a memory in advance.
  14. 11. The recording / recording device according to claim 10 , wherein after the focus jump operation is completed, the reflected light from the optical recording medium is detected by a light receiving element, and the spherical aberration correction is further optimized while observing the detection signal. Playback device.
  15. In a recording / reproducing apparatus having an optical pickup provided with an optical unit for correcting spherical aberration in an optical system and performing at least one of recording and reproduction on an optical recording medium having a plurality of recording layers.
    Correction state control means for controlling the correction state of spherical aberration in the optical unit;
    A function of storing a time required for a focus jump operation for jumping from a focus adjusted to a certain recording layer in the optical recording medium to a focus adjusted to another recording layer;
    The correction state control means starts the correction state change control in the optical unit simultaneously with the start of the focus jump operation ,
    At the end of the focus jump operation, control is performed so that the correction state of the optical unit is held within a predetermined range Sd ± ΔSd with respect to the optimum state Sd of spherical aberration correction corresponding to the other recording layer. ,
    Recording / playback device.
  16. 16. The recording / reproducing apparatus according to claim 15 , wherein the speed of change of the correction state by the correction state control means is controlled based on a predetermined reference time value or a focus jump operation time value stored in memory until the previous time.
  17. In a recording / reproducing apparatus having an optical pickup provided with an optical unit for correcting spherical aberration in an optical system and performing at least one of recording and reproduction on an optical recording medium having a plurality of recording layers.
    Correction state control means for controlling the correction state of spherical aberration in the optical unit;
    A function of storing a time required for a focus jump operation for jumping from a focus adjusted to a certain recording layer in the optical recording medium to a focus adjusted to another recording layer;
    The correction state control means starts control for changing the correction state in the optical unit before starting the focus jump operation ,
    The state of the optical unit has reached a predetermined correction state Sm intermediate between the optimal state Sc of spherical aberration correction corresponding to the certain recording layer and the optimal state Sd of spherical aberration correction corresponding to the other recording layer. Sometimes start the focus jump action,
    Further, at the end of the focus jump operation, the correction state of the optical unit is held within a predetermined range Sd ± ΔSd with respect to the optimum spherical aberration correction state Sd corresponding to the other recording layer. Control,
    Recording / playback device.
  18. 18. The recording / reproducing apparatus according to claim 17 , wherein the correction state changing speed by the correction state control means is controlled based on a predetermined reference time value or a focus jump operation time value stored in memory until the previous time.
JP2001197886A 2001-06-29 2001-06-29 Optical pickup and recording / reproducing apparatus Expired - Fee Related JP4788071B2 (en)

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JP4527657B2 (en) * 2005-11-30 2010-08-18 株式会社日立メディアエレクトロニクス Information playback device
JP4584172B2 (en) * 2006-03-24 2010-11-17 シャープ株式会社 Optical pickup control device and control method, optical disk device, optical pickup control program, and recording medium recording the program
JP4420920B2 (en) 2006-11-08 2010-02-24 ソニーオプティアーク株式会社 Optical recording medium driving device and focus-on method
JP5017183B2 (en) 2008-06-10 2012-09-05 株式会社日立製作所 Focus pull-in method and optical disc apparatus
JP5091836B2 (en) 2008-11-07 2012-12-05 株式会社日立製作所 Multi-layer optical disc focus jump method
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CN102037510B (en) * 2009-03-17 2014-06-04 松下电器产业株式会社 Optical disc device, focus control method and integrated circuit
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JP5615264B2 (en) * 2009-04-10 2014-10-29 パナソニック株式会社 Optical disc apparatus and interlayer jump method in multilayer optical disc
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