JP2006012296A - Optical disk apparatus and inter-layer jump control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform layer jump always safely and surely in a blue ray disk. <P>SOLUTION: By an acceleration/deceleration pulse 300 superimposed on a focus control signal 200 controlling a position of a condensed spot of a laser beam, for example, from L0 to L1, timing at which the condensed spot of the laser beam is jumped to a recording layer of a target is made always constant by superimposing the acceleration/deceleration pulse 300 on the focus control signal 200 at a point of time at which a fixed time (t) elapses from a rotary synchronizing signal 400 synchronizing with rotation of an optical disk (blue ray disk). Thereby, even if wobbling or the like of the blue ray disk is large, layer jump is performed always safely and surely. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical disc apparatus for recording / reproducing an optical disc having a plurality of recording layers, and more particularly to an interlayer jump control method for changing a recording layer to be recorded / reproduced.

  In recent years, a method for realizing a large-capacity optical disk recording / reproducing apparatus by shortening the wavelength of a light source and increasing the numerical aperture of an objective lens in an optical disk apparatus typified by a recording / reproducing apparatus for a recording medium such as an optical disk has been proposed. In this method, a blue-violet semiconductor laser having a wavelength of 405 nm and an objective lens having a numerical aperture of 0.85 are used, and a double-layer disc or the like having a recording capacity exceeding 23 Gbytes per layer is standard as a Blu-ray disc (hereinafter referred to as BD). It has become.

As a method for accurately performing the layer jump of a conventional multilayer optical disk such as a DVD, the surface shake component of the optical disk is added to the layer jump control signal (see, for example, Patent Document 1), or a past focus error signal is used. Has been reported. Further, although not a layer jump, a method of performing a stable track jump in consideration of the eccentricity and surface runout of an optical disc when performing a track jump is known (for example, see Patent Document 2).
JP 2001-84599 A (page 4-8, FIG. 1) JP 2000-20967 (page 5-6, Fig. 1)

  However, when the interlayer distance is shorter than that of a conventional optical disk such as a BD and the objective lens has a high numerical aperture, the focus pull-in range is narrowed. In such an optical disc, when the surface runout is large or there is a local variation in the interlayer distance in the rotation direction, this cannot be dealt with. That is, if the surface runout is large or the interlayer distance varies locally in the rotation direction, it is not known at which position in the phase of the runout the jump is made, so the layer jump timing is not determined and the layer jump is performed stably. There is a problem that can not be.

  The present invention has been devised in view of the above circumstances, and an object of the present invention is to provide an interlayer jump control method and an optical disc apparatus capable of always and stably performing a layer jump in a Blu-ray disc. .

  In order to achieve the above-described object, the present invention provides a laser beam condensing spot when the optical disc having a plurality of recording layers is recorded and reproduced by positioning the laser light condensing spot on a target recording layer through an optical system. An interlayer jump control method for changing a recording layer to be recorded / reproduced by placing an acceleration / deceleration pulse for operating a focus actuator on a focus control signal for controlling a position, wherein the acceleration / deceleration pulse is transmitted in synchronization with rotation of the optical disc. It is characterized in that an interlayer jump is performed on the focus control signal, and spherical aberration control of the optical system accompanying the interlayer jump is performed.

  Further, the present invention controls the position of the laser light focusing spot when an optical disc having a plurality of recording layers is recorded and reproduced by positioning the laser light focusing spot on a target recording layer through an optical system. An optical disc apparatus having a surface blur correction function for changing a recording layer to be recorded and reproduced by adding an acceleration / deceleration pulse for operating a focus actuator to a focus control signal and adding a signal for correcting the surface blur of the optical disc to the focus control signal A rotation synchronization signal generating means for generating a rotation synchronization signal synchronized with the rotation of the optical disc, and an interlayer jump control for placing the acceleration / deceleration pulse on the focus control signal after a predetermined time has elapsed from the generation of the rotation synchronization signal. And spherical aberration control means for controlling the spherical aberration of the optical system accompanying the interlayer jump when the predetermined time has elapsed. It is characterized in.

  As described above, in the present invention, the timing for jumping the focused spot of the laser beam to the target recording layer by the acceleration / deceleration pulse placed on the focus control signal for controlling the position of the focused spot of the laser beam is synchronized with the rotation of the optical disc. By always placing the acceleration / deceleration pulse on the focus control signal at a predetermined timing, the layer jump of an optical disc such as a Blu-ray disc can always be performed stably and reliably.

  According to the present invention, the timing for jumping the focused spot of the laser beam to the target recording layer by the acceleration / deceleration pulse put on the focus control signal for controlling the position of the focused spot of the laser beam is synchronized with the rotation of the optical disc. By always setting the acceleration / deceleration pulse to the focus control signal at the timing, the layer jump of an optical disc such as a Blu-ray disc can always be performed stably and reliably.

  The timing for jumping the focused spot of the laser beam to the target recording layer by the acceleration / deceleration pulse placed on the focus control signal that controls the position of the focused spot of the laser beam for the purpose of always performing the layer jump of the Blu-ray Disc stably and reliably. Is realized by always setting the acceleration / deceleration pulse on the focus control signal at a predetermined timing synchronized with the rotation of the optical disk.

  FIG. 1 is a block diagram showing a configuration of an optical disc apparatus according to an embodiment of the present invention. The optical disk device includes an optical pickup 14, a laser diode (LD) drive circuit 15, a matrix circuit 16, a signal processing circuit 17, a spherical aberration control circuit 18, an actuator control circuit 19, a motor control circuit 20, a spindle motor 21, and a rotation of the optical disk. A rotation synchronization detection circuit 22 that generates a synchronized signal is provided.

  Next, the operation of the present embodiment will be described. The reproduction signal read from the optical disk 11 by the optical pickup 14 is calculated by the matrix circuit 16 into each servo error signal and RF signal. Each of the calculated signals is subjected to gain adjustment and phase compensation by the signal processing circuit 17, the number of rotations of the spindle motor 21 is controlled through the motor control circuit 20, and the focus of the optical pickup 14 through the actuator control circuit 19. The control and tracking control actuators are controlled, and the liquid crystal element 5 (see FIG. 2), which is the wavefront conversion element of the optical pickup, is controlled via the spherical aberration control circuit 18, and the optical pickup (not shown) is controlled by the low frequency component of the tracking control. Feed control in the radial direction is performed via the feed control circuit. In addition, the laser diode (LD) drive circuit 15 controls the semiconductor laser 1 of the optical pickup 14 based on the signal obtained from the light emitting output detection light receiving element 10 of the optical pickup 14 to record and reproduce information on the optical disk 8. ing. At that time, the rotation synchronization detection circuit 22 generates a signal synchronized with the rotation of the optical disk 8 based on the rotation signal (FG signal) obtained from the spindle motor 21 and inputs the signal to the signal processing circuit 17.

  The signal processing circuit 17 generates a focus control signal for the optical pickup 14 and outputs the focus control signal to the actuator control circuit 19 to determine the focus of the optical pickup 14 as a target layer. At the same time, the signal processing circuit 17 generates a signal for controlling the timing for performing the layer jump from the rotation synchronization signal of the optical disc 8 and an acceleration / deceleration pulse signal to be added to the focus control signal for performing the layer jump. An acceleration / deceleration pulse signal is placed on the focus control signal at a timing determined by the signal and output to the actuator control circuit 19. The signal processing circuit 17 outputs a spherical aberration control signal for correcting spherical aberration of the optical system of the optical pickup 14 to the spherical aberration control circuit 18 at a timing determined by the timing control signal.

  FIG. 2 is a diagram showing the configuration of the optical pickup shown in FIG. The optical pickup 14 includes a semiconductor laser 1, a collimator lens 2, a diffraction grating 3, a polarization beam splitter 4, a wavefront conversion element 5, a quarter wavelength plate 6, a high numerical aperture objective lens 7, an optical information recording medium (optical disk) 8, It has a condensing lens 9, a light emitting output detecting light receiving element 10, a condensing lens 11, a multi lens 12, and a RF signal detecting light receiving element 13.

  Next, the operation of the present embodiment will be described. The emitted light from the semiconductor laser 1 is converted into parallel light by the collimator lens 2, passes through the side spot generating diffraction grating 3 used for calculating the tracking control error signal, and is a polarized beam for dividing the emitted light. It passes straight through the splitter 4. The laser beam that has passed through the polarization beam splitter 4 is a wavefront conversion element (for correcting spherical aberration caused by the thickness error of the cover layer (8a) from the disk surface to the information recording layer and the cover layer (8b) between the information recording layers). Here, a liquid crystal element is used as an example), and after passing through a quarter-wave plate 6 for converting linearly polarized laser light into circularly polarized light, an optical information recording medium is obtained by a high numerical aperture objective lens 7. Focused on (optical disk) 8. At the same time, a part of the emitted light is reflected by the polarization beam splitter 4 and then guided to the light receiving element 10 for detecting the light output by the condenser lens 9 for the purpose of controlling the laser output to be a constant value. Used.

  On the other hand, the reflected light from the optical disk 8 is received by the high numerical aperture objective lens 7, reflected by the polarization beam splitter 4, and then guided to the detection optical path on the condenser lens 11 side. In this example, the astigmatism method is used as the focus control error method, and the differential push-pull method is used as the tracking control error signal. The convergent light passing through the condensing lens 11 and the multi lens 12 is a servo error signal. And it enters into the RF signal detection light receiving element 13 and is photoelectrically converted. The matrix circuit 16 in FIG. 1 calculates a focus control error signal, a tracking control error signal, a spherical aberration control error signal, an RF signal for signal processing and a SUM signal which is a low-frequency component from the signals of these light receiving elements. Ask.

  Next, a method for jumping between layers of a multilayer optical disk using the optical pickup shown in FIG. 2 will be described. As shown in FIG. 3, when jumping from a state where focus control is performed so that a certain information recording layer (L0) is in focus to another information recording layer (L1), the signal processing circuit 17 is in advance from the surface of the optical disc. The spherical aberration control signal 100 that has corrected the spherical aberration for the cover layer up to L0 is changed to be corrected for the cover thickness from the surface to L1 (time t0), and then the focus is moved to L1. Therefore, the focal position (the position of the focal spot of the laser beam) is jumped from L0 to L1 by giving an acceleration / deceleration pulse 300 for accelerating / decelerating the focus actuator to the focus control signal 200 (time t1).

  Here, when there is a surface shake on the optical disc 8, a jump is stably performed by adding the surface shake of the focus control signal 200 to the acceleration / deceleration pulse signal 300 for layer jump as shown in FIG. Yes. At this time, as described in the background art, when the surface shake of the optical disk 8 is large or the interlayer distance varies locally in the rotation direction, it is not known at which position of the surface shake phase it jumps, so that it is stable. Cannot jump layers.

  Therefore, in order to eliminate the above inconvenience, the signal processing circuit 17 detects a rotation synchronization signal 400 synchronized with the rotation of the optical disk 8 from the FG signal obtained from the spindle motor 21 as shown in FIG. Spherical aberration control associated with layer jump by changing the spherical aberration control signal after a certain time (t = t0) has elapsed since the rising or falling of the signal synchronized to rotate so that the phase component of the shake is always constant Is done. Furthermore, a layer jump is performed after a certain time (t1: where t1> t0) has elapsed.

  According to the present embodiment, since the layer jump is always performed at a fixed time (t1) synchronized with the rotation of the optical disc 8, the surface deflection of the optical disc 8 is large or the interlayer distance is locally in the rotation direction. Even when there is a variation, the layer jump timing can be performed in a constant and reliable manner, and the disturbance of the focus control signal 200 due to surface shake becomes constant, so that a stable layer jump can be performed at all times. Further, before performing the layer jump in synchronization with the rotation of the optical disc 8, the wavefront conversion element 5 is controlled so as to correct spherical aberration in advance corresponding to the cover layer interposed on the information recording layer of the jump destination. By doing so, it becomes possible to pull in quickly without disturbing the focus pull-in control after jumping due to surface shake.

  If the interlayer distance varies locally in the rotation direction and becomes unstable, the surface shake phase component of the timing at which the layer jump has been performed is changed (fixed time (t1, t2) is changed) ), A stable layer jump can be performed.

  Further, the layer jump is performed once or more, the acceleration / deceleration pulse 300 and the focus pull-in time at that time are stored, and learning is performed so that the acceleration / deceleration pulse 300 is optimal (the focus pull-in is the shortest). , You will be able to do a more stable layer jump.

  In addition, the present invention is not limited to the above-described embodiment, and can be implemented in various other forms in specific configurations, functions, operations, and effects without departing from the scope of the invention.

1 is a block diagram showing a configuration of an optical disc apparatus according to an embodiment of the present invention. It is the figure which showed the structure of the optical pick-up shown in FIG. It is a wave form diagram explaining the interlayer jump of an optical disk. It is another wave form diagram explaining the interlayer jump of an optical disk. It is another wave form diagram explaining the interlayer jump of an optical disk.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Semiconductor laser, 2 ... Collimator lens, 3 ... Diffraction grating, 4 ... Polarization beam splitter, 5 ... Wavefront conversion element, 6 ... 1/4 wavelength plate, 7 ... High numerical aperture objective lens, 8: Optical information recording medium (optical disk), 9: Condensing lens, 10: Light receiving element for detecting light emission output, 11: Condensing lens, 12: Multi lens, 13: Light receiving element for detecting RF signal , 14 …… Optical pickup, 15 …… Laser diode (LD) drive circuit, 16 …… Matrix circuit, 17 …… Signal processing circuit, 18 …… Spherical aberration control circuit, 19 …… Actuator control circuit, 20 …… Motor Control circuit, 21... Spindle motor, 22... Rotation synchronization detection circuit.

Claims (6)

When a laser beam focusing spot is positioned on a target recording layer through an optical system to record / reproduce an optical disc having a plurality of recording layers, the focus actuator controls the focus control signal for controlling the position of the laser beam focusing spot. An interlayer jump control method for changing a recording layer to be recorded and reproduced by placing an acceleration / deceleration pulse for operating
An interlayer jump control method comprising performing an interlayer jump by placing the acceleration / deceleration pulse on the focus control signal in synchronization with the rotation of the optical disc, and controlling the spherical aberration of the optical system in accordance with the interlayer jump.   2. The interlayer jump control method according to claim 1, wherein a signal for correcting surface blur of the optical disc is added to the focus control signal.   2. The interlayer jump control method according to claim 1, wherein the interlayer jump is performed after correcting the spherical aberration of the optical system in synchronization with the rotation of the optical disk. When a laser beam focusing spot is positioned on a target recording layer through an optical system to record / reproduce an optical disc having a plurality of recording layers, the focus actuator controls the focus control signal for controlling the position of the laser beam focusing spot. An optical disc apparatus having a surface blur correction function for changing a recording layer to be recorded and reproduced by adding an acceleration / deceleration pulse for operating the optical disc and adding a signal for correcting the surface blur of the optical disc to the focus control signal,
Rotation synchronization signal generating means for generating a rotation synchronization signal synchronized with the rotation of the optical disc;
Interlayer jump control means for placing the acceleration / deceleration pulse on the focus control signal after a predetermined time has elapsed since the generation of the rotation synchronization signal;
Spherical aberration control means for performing spherical aberration control of the optical system accompanying an interlayer jump at the time when the predetermined time has passed;
An optical disc apparatus comprising:   5. The optical disc apparatus according to claim 4, wherein the optical disc is a Blu-ray disc. 5. The optical disk apparatus according to claim 4, wherein the interlayer jump control unit places the acceleration / deceleration pulse on the focus control signal after performing spherical aberration control of the optical system by the spherical aberration control unit.

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