JP2007287230A - Device and method for controlling optical pickup, optical disk device, optical pickup control program, and recording medium on which program is recorded - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent erroneous control in correction of spherical aberration even when an aberration error signal is deviated from an ideal S-curve or a target value of the spherical error signal is deviated from 0 V. <P>SOLUTION: A servo DSP 16 controls an optical pickup 7. The optical pickup 7 includes a collimate lens driving mechanism 27 correcting the spherical aberration by moving a collimate lens 26 in an optical axis direction. The servo DSP 16 acquires the spherical aberration as an aberration error signal utilizing a signal from a photodetector 6, acquires a distance from an initial position of the optical pickup 7, and controls the collimate lens driving mechanism 27 on the basis of the aberration error signal when the acquired distance is within a prescribed range. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical pickup control device and control method for controlling an optical pickup provided with an aberration correction means for correcting spherical aberration occurring in an optical system, an optical disc device, an optical pickup control program, and a recording medium on which the program is recorded. It is.

  In recent years, there has been a demand for an increase in capacity of an optical disc recorded and / or reproduced in an optical disc apparatus. Therefore, a multilayer disc having a plurality of recording layers is widely used as an optical disc for achieving a large capacity. Further, as an optical disk apparatus for achieving a large capacity, development of an optical disk apparatus including an optical pickup using an objective lens having a short wavelength and a large numerical aperture has been advanced.

  Here, in a multi-layer disc having a plurality of recording layers, the spherical aberration that occurs when the cover layers have different thicknesses is proportional to the fourth power of the numerical aperture. For this reason, in an optical disk recording / reproducing apparatus using an objective lens having a large numerical aperture, correction of spherical aberration is essential in order to support a multilayer disk having a plurality of recording layers having different cover layer thicknesses.

Thus, for example, Patent Document 1 discloses a method of correcting spherical aberration by a servo mechanism using a liquid crystal element, a collimator lens, or an expander lens. This document describes that the spherical aberration caused by the cover layer thickness error is corrected by changing the position of the collimating lens. Further, in this document, as a method of detecting the spherical aberration as an electric signal, a focus position shift signal at the central portion and a focus position shift signal at the outer peripheral portion are detected with respect to the reflected light from the optical disc, and the difference signal is obtained. A method of detecting as a spherical aberration signal is described. By feeding back the spherical aberration signal to the spherical aberration correction element of the liquid crystal, the spherical aberration can be detected and corrected in real time.
Japanese Unexamined Patent Application Publication No. 2004-171635 (released on June 17, 2004)

  FIG. 9 shows an example of the correspondence between the position of the collimating lens and two aberration error signals (spherical aberration signals) in the method of correcting spherical aberration by moving the collimating lens (CL) in the optical axis direction. Yes.

  In the thin line graph shown in the figure, the aberration error signal draws an almost ideal S-shaped curve and monotonously decreases as the CL position increases. In this case, for example, if the target value of the aberration error signal is 0 V and the difference value obtained by subtracting the target value from the aberration error signal is positive, the collimator lens is moved to the end position side. If the difference value is negative, By moving to the home position side, the collimating lens can be moved toward the target position.

  On the other hand, in the illustrated bold line graph, the aberration error signal decreases in the vicinity of the home position with respect to an ideal S-shaped curve. In addition, the target value of the aberration error signal may deviate from 0 V due to a mounting error of a light receiving element that detects reflected light from the optical disk.

  Therefore, for example, the target value of the aberration error signal is set to 0.2 V, and if the difference value is positive, the collimating lens is moved to the end position side, and if the difference value is negative, it is moved to the home position side. At this time, in a region other than the vicinity of the home position, the collimating lens can be moved toward the target position as described above. However, in the vicinity of the home position, it moves to the home position side, so that the collimating lens is moved to the side opposite to the target position. As a result, spherical aberration cannot be corrected, and in the worst case, the collimating lens may collide with other members and be damaged.

  The present invention has been made in view of the above-described problems, and the purpose thereof is, for example, that the aberration error signal deviates from an ideal S-curve or the target value of the aberration error signal deviates from 0V. However, an object of the present invention is to provide an optical pickup control device that can prevent erroneous control of correction of spherical aberration.

  An optical pickup control apparatus according to the present invention is an optical pickup control apparatus that controls an optical pickup provided with an aberration correction unit that corrects spherical aberration generated in the optical system by changing an optical element in the optical system. In order to solve the above problems, an aberration error signal acquisition unit that acquires the spherical aberration as an aberration error signal, a change amount acquisition unit that acquires a change amount from an initial state of the optical element, and the change amount is within a predetermined range. And an aberration correction control means for controlling the aberration correction means based on the aberration error signal.

  Here, the optical element used to correct the spherical aberration includes a liquid crystal element that changes the phase of the light beam between the central part and the peripheral part of the region irradiated with the light beam from the light source, and the optical axis direction. And a lens element such as a beam expander or a collimating lens that changes the light beam from parallel light to divergent light or focused light.

  As the amount of change in the optical element, in the case of a liquid crystal element, the amount of change in the alignment of the liquid crystal and the amount of change in the voltage applied to the liquid crystal element corresponding to the amount of change in the alignment can be mentioned. In the case of a lens element, the amount of change in the position of the lens element in the optical axis direction and the amount of change corresponding thereto can be mentioned. Here, as the amount of change corresponding to the amount of change in the position of the lens element in the optical axis direction, when the lens element is driven by a voice coil, the amount of change in the current passed through the voice coil can be mentioned. In the case of driving with, the amount of change in the number of pulses input to the stepping motor can be mentioned.

  According to said structure, control of the aberration correction means based on an aberration error signal is controlled when the variation | change_quantity of the said optical element is in a predetermined range. As a result, if the aberration error signal deviates from the ideal S-curve or the target value of the aberration error signal deviates from 0 V, and the change amount is outside the predetermined range, the aberration correction based on the aberration error signal is performed. Control of the means can be stopped. As a result, erroneous control of spherical aberration correction can be prevented.

  Incidentally, the amount of change (zero) in the initial state is often outside the predetermined range. For this reason, usually, after the optical element is changed from the initial state to a state corresponding to the recording layer of the optical disc on which the optical system is focused, the control of the aberration correction unit based on the aberration error signal is performed. Done. Therefore, in the control apparatus for an optical pickup according to the present invention, it is preferable that the aberration correction unit is controlled based on the aberration error signal when the amount of change after the change is within the predetermined range.

  In the control apparatus for an optical pickup according to the present invention, the aberration correction control unit controls the variation amount to be out of the predetermined range when the aberration correction unit is controlled based on the aberration error signal. Is preferably not performed on the aberration correcting means. In this case, while the aberration correction unit is controlled based on the aberration error signal, the change amount does not deviate from the predetermined range. Therefore, erroneous control of spherical aberration correction can be reliably prevented.

  The predetermined range preferably includes a change amount when the optical element is changed from the initial state to a state corresponding to the recording layer of the optical disc on which the optical system collects light.

  The predetermined range is preferably a range in which the value of the aberration error signal monotonously decreases with respect to the change amount. In this range, it is possible to appropriately correct spherical aberration based on the aberration error signal. Therefore, erroneous control of spherical aberration correction can be reliably prevented.

  Furthermore, it is preferable that the predetermined range has a median value of the predetermined range when the value of the aberration error signal is equal to a target value for correcting the spherical aberration. In this case, in the predetermined range, the magnitude of the range in which the value of the aberration error signal is larger than the target value is approximately the same as the magnitude of the range in which the value of the aberration error signal is smaller than the target value.

  For example, in the case of spherical aberration due to the thickness of the cover layer of the optical disk, since the optical disk rotates, the time-series waveform of the aberration error signal becomes a waveform that vibrates from the target value. Therefore, if the value of the aberration error signal deviates significantly from the target value, it is considered that some disturbance has occurred. In such a case, the aberration correction means is not controlled based on the aberration error signal, so that spherical aberration is prevented. Incorrect control of the correction can be prevented more reliably.

  In the control apparatus for an optical pickup according to the present invention, it is preferable that the aberration correction unit includes a stepping motor that moves the optical element stepwise from the initial position in the optical axis direction. The stepping motor is a motor that rotates a rotating shaft by a predetermined angle when a predetermined pulse current flows. Therefore, the number of pulses of the pulse current can be made to correspond to the change amount, and as a result, the change amount can be easily acquired.

  By the way, when a new aberration correction unit is provided for the conventional optical pickup, electric power for operating the aberration correction unit is required. It is desirable to suppress this power consumption from the recent trend of power saving.

  As a result of various studies, the inventors of the present application have found that spherical aberration can be corrected satisfactorily even if the aberration error signal gently follows the target value, and devised the following invention. did.

  That is, in order to solve the above-described problem, the optical pickup control device according to the present invention includes an aberration correction unit that corrects spherical aberration generated in the optical system by changing optical elements in the optical system stepwise. An optical pickup control apparatus for controlling a pickup, comprising: an aberration error signal acquisition means for acquiring the spherical aberration as an aberration error signal; a value of the value of the aberration error signal and a target value for correcting the spherical aberration; And an aberration correction control means for controlling the aberration correction means so as to change the optical element stepwise based on the comparison result.

  Here, it is desirable to change the optical element by one step in order to change the optical element stepwise.

  In the case of a normal servo mechanism, the aberration correction control means controls the aberration correction means based on the difference of the aberration error signal with respect to the target value. Specifically, the aberration correction control means controls the aberration correction means so that the optical element is changed more greatly as the difference is larger.

  On the other hand, in the present invention, the aberration correction control means controls the aberration correction means so as to change the optical element stepwise based on the magnitude of the aberration error signal with respect to the target value. Accordingly, the optical element is changed stepwise regardless of the magnitude of the difference, so that the optical element is not greatly changed even if the magnitude of the difference is large. Therefore, since the change of an optical element can be suppressed, the power consumption required in order to change an optical element can be suppressed.

  An optical pickup that records and / or reproduces information by irradiating an optical disk with an optical beam, provided that the optical pickup device includes the optical pickup having the above-described configuration and the control device for the optical pickup having the above-described configuration. The same effects as described above can be achieved.

  An optical pickup control method according to the present invention is an optical pickup control method including an aberration correction unit that corrects spherical aberration generated in the optical system by changing an optical element in the optical system. Therefore, an aberration error signal acquisition step for acquiring the spherical aberration as an aberration error signal, a step number acquisition step for acquiring the number of steps from the initial state of the optical element, and the number of steps is within a predetermined range. And an aberration correction control step for controlling the aberration correction means based on the aberration error signal.

  According to the above method, the control of the aberration correction unit based on the aberration error signal is restricted when the change amount of the optical element is within a predetermined range. As a result, if the aberration error signal deviates from the ideal S-curve or the target value of the aberration error signal deviates from 0 V, and the change amount is outside the predetermined range, the aberration correction based on the aberration error signal is performed. Control of the means can be stopped. As a result, erroneous control of spherical aberration correction can be prevented.

  An optical pickup control method according to the present invention is an optical pickup control method including aberration correction means for correcting spherical aberration generated in the optical system by changing optical elements in the optical system stepwise. In order to solve the problem, the aberration error signal acquisition step of acquiring the spherical aberration as an aberration error signal, the value of the aberration error signal, and the target value for correcting the spherical aberration are compared, and based on the comparison result And an aberration correction control step for controlling the aberration correction means so as to change the optical element stepwise.

  According to the above method, in the aberration correction control step, the aberration correction means is controlled so as to change the optical element stepwise based on the magnitude of the aberration error signal with respect to the target value. Accordingly, the optical element is changed stepwise regardless of the magnitude of the difference, so that the optical element is not greatly changed even if the magnitude of the difference is large. Therefore, since the change of an optical element can be suppressed, the power consumption required in order to change an optical element can be suppressed.

  Each means in the optical pickup control device can be executed on a computer by an optical pickup control program. Further, the optical pickup control program can be executed on an arbitrary computer by storing the optical pickup control program in a computer-readable recording medium.

  As described above, the control device for the optical pickup according to the present invention controls the aberration correction unit based on the aberration error signal when the change amount of the optical element is within a predetermined range. There is an effect that erroneous control of correction can be prevented.

  Before describing the embodiments of the present invention, the configuration of an optical disk recording / reproducing apparatus (optical disk apparatus) common to the embodiments will be described with reference to FIGS.

  FIG. 1 shows a main configuration of the optical disc recording / reproducing apparatus. FIG. 2 shows the main structure of the optical pickup 7 in the optical disc recording / reproducing apparatus 30. The optical disk recording / reproducing apparatus 30 is an apparatus for recording and reproducing information with respect to the optical disk 1.

  The optical disk 1 may be an optical disk, and the type thereof is not limited, for example, a magneto-optical disk. Further, the present invention can be applied to an optical disk reproducing apparatus that only reproduces information from the optical disk 1, and can also be applied to an optical disk recording apparatus that performs only information recording on the optical disk 1.

  As shown in FIG. 1, the optical disk recording / reproducing apparatus 30 includes an optical pickup 7, various motors 8, 11, 22, various drivers 10, 12, 13, 14, 23, 25, and an RF (high frequency) processing circuit 9. , Various control circuits 15, 16, 18, a signal processing circuit 17, and various external I / Fs (interfaces) 19. The optical disc recording / reproducing apparatus 30 is connected to the host computer 20 via the host interface 19. The optical disc recording / reproducing device 30 is connected to the display device 21.

  First, the drive part of the optical disc recording / reproducing apparatus 30 will be described. The spindle motor 11 rotates the optical disc 1. The spindle motor 11 includes a circuit that generates a pulse signal as the motor rotates, and this pulse signal is transmitted to a servo DSP (Digital Signal Processor) 16.

  The optical pickup 7 irradiates the optical disc 1 with a light beam to record / reproduce information on the optical disc 1. The sled motor 8 drives the optical pickup 7 in the radial direction with respect to the optical disc 1. The tilt motor 22 adjusts the tilt of the optical pickup 7 with respect to the optical disc 1.

  As shown in FIGS. 1 and 2, the optical pickup 7 includes an objective lens 2, an actuator 3, a semiconductor laser (LD) 4, photodetectors (PD) 5 and 6, a tilt sensor 24, a collimating lens 26, and a collimating lens. A drive mechanism 27, a beam splitter 28, and a mirror 32 are provided.

  The semiconductor laser 4 is a light source for irradiating the optical disk 1 with a light beam, and emits the light beam. The wavelength of the light beam emitted from the semiconductor laser 4 is defined by a standard such as DVD (Digital Versatile Disk).

  The beam splitter 28 reflects a part of the light beam emitted from the semiconductor laser 4 to guide it to the photodetector 5 and transmits the remaining most part. The beam splitter 28 reflects reflected light from the optical disc 1 and guides it to the photodetector 6. A hologram can be used instead of the beam splitter 28.

  The photodetectors 5 and 6 have a light receiving element and convert light incident on the light receiving element into an electric signal. The photodetector 5 detects a part of the direct light from the semiconductor laser 4 in order to detect the power of the light beam emitted from the semiconductor laser 4, and transmits the detected signal to the automatic output control circuit 15. To do. On the other hand, the photodetector 6 detects reflected light from the optical disk 1 and transmits various signals such as a detected servo error signal, RF signal, and wobble signal to the RF processing circuit 9.

  Here, the RF signal and the wobble signal are signals (reproduction signals) recorded on the optical disc 1. The RF signal indicates data recorded on the optical disc 1, and the wobble signal indicates an address on the optical disc 1. Normally, the photodetector 5 has one light receiving element, and the photodetector 6 has a plurality of light receiving elements.

  The collimating lens 26 collects the light beam emitted from the semiconductor laser 4 and passed through the beam splitter 28 and converts it into substantially parallel light. In the present embodiment, the collimating lens 26 is movable in the optical axis direction by the collimating lens driving mechanism 27 in order to correct the spherical aberration of the light beam applied to the optical disc 1.

  As shown in FIG. 2, the collimating lens driving mechanism 27 includes a stepping motor 33 that generates a rotational force, a feed screw 34 to which the rotational force is transmitted from a rotation shaft of the stepping motor 33 via a gear, and a feed screw. 34 and a holder 35 that holds the collimating lens 26.

  The stepping motor 33 is a motor that rotates a rotating shaft by a predetermined angle when a predetermined pulse current flows. The feed screw 34 is provided such that its axial direction is parallel to the optical axis direction of the collimating lens 26. Thereby, the rotational movement in the feed screw 34 is converted into the linear movement in the optical axis direction of the collimating lens 26 by the holder 35. As a result, the collimating lens 26 can be moved in the optical axis direction.

  As shown in FIG. 2, the mirror 32 is disposed between the collimating lens 26 and the objective lens 2, bends the light beam from the collimating lens 26 and guides it to the objective lens 2, and from the objective lens 2. The light beam is bent and guided to the collimating lens 26.

  The objective lens 2 is for condensing the light beam from the semiconductor laser 4 on the optical disc 1 and guiding the reflected light from the optical disc 1 to the photodetector 6. The objective lens 2 is driven by an actuator 3.

  The actuator 3 drives the objective lens 2. The actuator 3 is driven and controlled by an actuator driver 13.

  Specifically, the actuator 3 drives the objective lens 2 in the focus direction that is the optical axis direction of the objective lens 2 and the radial direction that is the radial direction of the optical disc 1. The actuator 3 has a focus coil 52 (see FIG. 3) that is a voice coil that drives the objective lens 2 in the focus direction, and a tracking coil that is a voice coil that drives the objective lens 2 in the radial direction as a drive mechanism of the objective lens 2. 56 (see FIG. 4). In addition to the voice coil, a known drive mechanism can be used as the drive mechanism of the actuator 3.

  The tilt sensor 24 is a sensor for detecting a tilt angle between the optical pickup 7 and the optical disc 1. Here, the tilt angle refers to an angle formed by the normal direction of the recording surface of the optical disc 1 and the optical axis direction of the objective lens 2. If the tilt angle is large, the quality of recording and / or reproduction is deteriorated. Therefore, the tilt sensor 24 detects the tilt angle (tilt error), and the tilt motor 22 adjusts the tilt of the optical pickup 7 based on the tilt angle. As a result, the optimum recording and / or reproduction quality can be maintained.

  Next, the circuit portion of the optical disc recording / reproducing apparatus 30 will be described. The thread driver 10, spindle motor driver 12, actuator driver 13, tilt driver 23, and collimating lens drive motor driver 25 drive control the thread motor 8, spindle motor 11, actuator 3, tilt motor 22, and stepping motor 33, respectively. To do.

  The laser driver 14 controls the driving of the semiconductor laser 4. The automatic output control circuit (APC) 15 compares the laser light detection level detected by the photodetector 5 with a reference level serving as a reference, controls the laser driver 14 based on the comparison result, and controls the laser. Make the light output constant. Specifically, the APC circuit 15 controls the laser driver 14 to lower the laser light output when the detection level is higher than the reference level and to increase the laser light output when the detection level is lower than the reference level. To do.

  Further, when recording data on the optical disk 1, the laser driver 14 drives and controls the semiconductor laser 4 based on the recording signal received from the signal processing circuit 17. The semiconductor laser 4 at the time of recording emits pulses, but emits light at a recording power, so that the level of the reflected signal from the optical disk 1 detected by the photodetector 6 is larger than that at the time of reproduction. turn into. For this reason, the photodetector 6 has a function of performing gain switching between reproduction and recording. As a result, the level of the servo error signal sent to the RF processing circuit 9 during recording is prevented from increasing. During recording, the APC circuit 15 performs an APC operation so that the semiconductor laser 4 emits light with a power suitable for recording.

  The laser driver 14 performs write strategy processing when recording data on the optical disc 1. The write strategy process is a process of changing the recording method according to a subtle difference of the optical disk 1 when the recording signal is actually recorded on the optical disk 1. The write strategy process utilizes the fact that recording on the optical disc 1 is thermal recording. Recording performance can be improved by the write strategy processing.

  The RF processing circuit 9 performs IV conversion of a signal sent from the photodetector 6 from a current signal to a voltage signal. The RF processing circuit 9 outputs the converted voltage signal to the signal processing circuit 17 and outputs it to the servo DSP 16 via the A / D converter (see FIGS. 3 and 4).

  More specifically, the RF processing circuit 9 performs IV conversion on the reproduction signal from the photodetector 6, performs waveform shaping processing, and transmits the result to the signal processing circuit 17. Further, the RF processing circuit 9 performs IV conversion on the servo error signal from the photodetector 6, performs waveform shaping processing, and then transmits it to the servo DSP 16 via the A / D converter. .

  The servo DSP 16 performs various arithmetic processes based on the servo error signal received from the photodetector 6 via the RF processing circuit 9, and performs errors for various servos such as focus servo, tracking servo, and aberration servo for the objective lens. Generate a signal. A known method can be used to generate each error signal. For example, a focus error signal that is an error signal for focus servo can be generated by an astigmatism method or a knife edge method. A tracking error signal that is an error signal for tracking servo can be generated by a differential push-pull method. In addition, an aberration error signal, which is an error signal for aberration servo, can be generated by differential focus error signals between the central portion and the peripheral portion of the light beam.

  The servo DSP 16 generates a drive instruction signal for driving the actuator 3 based on the generated focus error signal and tracking error signal, and transmits the drive instruction signal to the actuator driver 13. The actuator driver 13 drives and controls the actuator 3 based on the drive instruction signal. Thereby, focus servo and tracking servo control for the actuator 3 is performed. Details of the focus servo and tracking servo will be described later.

  When the servo DSP 16 receives from the system controller 18 a jump instruction signal instructing to jump to a certain track of the optical disc 1, a thread drive instruction for driving the sled motor 8 based on the received jump instruction signal. A signal is generated and transmitted to the thread driver 10. The thread driver 10 drives and controls the thread motor 8 based on the received thread drive instruction signal. The servo DSP 16 may generate a thread drive instruction signal for driving the thread motor 8 based on the tracking servo error signal, and transmit the thread drive instruction signal to the thread driver 10. In this case, tracking servo for the optical pickup 7 is performed.

  The servo DSP 16 generates a drive instruction signal for driving the spindle motor 11 at an appropriate rotational speed based on the pulse signal received from the spindle motor 11, and transmits the drive instruction signal to the spindle motor driver 12. The spindle motor driver 12 drives and controls the spindle motor 11 based on the received drive instruction signal.

  Further, the servo DSP 16 generates a tilt drive instruction signal for driving the optical pickup 7 to an appropriate tilt based on the tilt error signal received from the tilt sensor 14 via the RF processing circuit 9, and the tilt driver 23. Send to. The tilt driver 23 drives and controls the tilt motor 22 based on the received tilt drive instruction signal.

  The servo DSP 16 generates a drive instruction signal for driving the collimator lens 26 based on the generated aberration error signal, and transmits the drive instruction signal to the collimator lens drive motor driver 25. The collimating lens driving motor driver 25 drives and controls the collimating lens driving mechanism 27 (stepping motor 33) based on the driving instruction signal. Thereby, servo control for the collimating lens 26, that is, spherical aberration servo is performed. Details of the spherical aberration servo will be described later.

  On the other hand, the signal processing circuit 17 performs processing such as demodulation and waveform shaping on the RF signal in the reproduction signal, and further performs error correction processing to reproduce the original data. The reproduced data is transmitted from the signal processing circuit 17 to the host computer 20 via the host interface 19.

  Similarly, the signal processing circuit 17 performs processing such as demodulation, waveform shaping, and error correction on the wobble signal in the reproduction signal to reproduce the address signal. The reproduced address signal is transmitted from the signal processing circuit 17 to the system controller 18 and used as address information by the system controller 18.

  The signal processing circuit 17 generates a clock signal from each of the RF signal and the wobble signal. A synchronization signal is generated from this clock signal. For example, the clock signal is transmitted to the servo DSP 16 and used to control the rotation of the spindle motor 11 in synchronization with the RF signal.

  The signal processing circuit 17 receives data from the host computer 20 via the host interface 19 when recording data on the optical disc 1. The signal processing circuit 17 adds a flag for error correction to the received data, further performs modulation processing, and then transmits it to the laser driver 14 as a recording signal.

  The system controller 18 is for overall control of various components in the optical disc recording / reproducing apparatus 30. The function of the system controller 18 is realized by the CPU executing a program stored in a storage device such as a RAM or a flash memory.

  Next, details of the focus servo, tracking servo, and spherical aberration servo will be described with reference to FIGS. FIG. 3 shows a configuration relating to focus servo and spherical aberration servo in the optical disc recording / reproducing apparatus 30. FIG. 4 shows a configuration related to tracking servo in the optical disc recording / reproducing apparatus 30.

  3 and 4, the servo DSP 16 includes a servo controller 40, an error signal generation circuit 41, various focus servo compensation circuits 42, a ramp circuit 43, various aberration servo compensation circuits 44, a jump control circuit 45, a stepping. The motor control circuit 46 includes a tracking servo compensation circuit 47, a track jump control circuit 48, and various switches SW1 to SW6.

  The servo controller 40 performs overall control of various components in the servo DSP 16. Specifically, the servo controller 40 controls the focus servo various compensation circuits 42 and the tracking servo various compensation circuits 47 based on the instruction signal from the system controller 18 and various error signals from the error signal generation circuit 41. Or controls turning on / off of the switches SW1 to SW6. The details of the servo controller 40 will be described later.

  The error signal generation circuit 41 performs various arithmetic processing based on the error signal received from the photodetector 6 via the RF processing circuit 9 (see FIG. 1) and the A / D converter 36, and based on the calculation result, A focus error signal, a tracking error signal, and an aberration error signal are generated. The error signal generation circuit 41 transmits a focus error signal to the focus servo various compensation circuits 42, a tracking error signal to the tracking servo various compensation circuits 47, and an aberration error signal to the aberration servo various compensation circuits 44. In addition, the error signal generation circuit 41 transmits the generated focus error signal, tracking error signal, and aberration error signal to the servo controller 40.

  The various focus servo compensation circuits 42 generate a drive instruction signal for driving the focus coil 52 of the actuator 3 based on the focus error signal. At this time, the focus servo compensation circuit 42 performs various compensations in order to drive the focus coil 52 optimally. As an example of this compensation, there is a phase compensation for preventing oscillation due to the positive feedback of the phase of the control system exceeding 180 degrees.

  The ramp circuit 43 generates a drive instruction signal for moving the objective lens 2 from a reference position before operation to a position where focus servo is performed.

  The switch SW2 switches between a drive instruction signal from the focus servo compensation circuit 42 and a drive instruction signal from the ramp circuit 43 based on an instruction from the servo controller 40. The switch SW1 selects whether or not to send a drive instruction signal from the focus servo various compensation circuit 42 or the ramp circuit 43 to the actuator driver 13 based on an instruction from the servo controller 40. The focus servo is turned on / off by the switch SW1.

  The drive instruction signal from the focus servo compensation circuit 42 or the ramp circuit 43 via the switch SW2 and the switch SW1 is converted into an analog signal by the D / A converter 50, and then the focus driver 51 of the actuator driver 13. Is input. The focus driver 51 controls the drive of the focus coil 52 by converting the drive instruction signal into an appropriate signal level and inputting it to the focus coil 52. Thereby, the objective lens 2 can be moved to a desired position in the optical axis direction.

  On the other hand, the various aberration servo compensation circuits 44 generate a movement instruction signal for moving the collimator lens 26 to a position based on the aberration error signal. At this time, the various aberration servo compensation circuits 44 perform various compensations in order to optimally drive the collimating lens drive motor 33. As an example of this compensation, there is a phase compensation for preventing oscillation due to the positive feedback of the phase of the control system exceeding 180 degrees.

  The jump control circuit 45 generates a movement instruction signal for moving the collimator lens 26 from a reference position before operation to a position where aberration servo is performed.

  The switch SW4 switches between a movement instruction signal from the aberration servo compensation circuit 44 and a movement instruction signal from the jump control circuit 45 based on an instruction from the servo controller 40. The switch SW3 selects whether or not to send a movement instruction signal from the aberration servo compensation circuit 44 or the jump control circuit 45 to the stepping motor control circuit 46 based on an instruction from the servo controller 40. The aberration servo is turned on / off by the switch SW3.

  The stepping motor control circuit 46 generates a drive instruction signal for driving the collimating lens drive motor 33 that is a stepping motor based on the movement instruction signal from the various aberration servo compensation circuit 44 or the jump control circuit 45. This drive instruction signal is a pulse voltage, is converted into a predetermined pulse current by the collimating lens drive motor driver 25, and is output to the stepping motor 33. The rotation axis of the stepping motor 33 rotates in a certain direction by a predetermined angle. . Thereby, the collimating lens 26 moves by a predetermined amount in a certain direction in the optical axis direction. When the pulse voltage is negative, the rotation axis of the stepping motor 33 rotates by a predetermined angle in the opposite direction, and the collimating lens 26 moves by a predetermined amount in the opposite direction of the optical axis direction.

  Accordingly, the stepping motor control circuit 46 counts as a drive instruction signal, for example, +1 when a positive pulse voltage is output, and counts −1 when a negative pulse voltage is output (FIG. 5). ). Thereby, the distance (change amount) from the reference position of the collimating lens 26 to the current position can be detected. The stepping motor control circuit 46 transmits information on the count value of the position pulse counter 103 to the servo controller 40.

  The drive instruction signal generated by the stepping motor control circuit 46 is converted into an analog signal by the D / A converter 53 and then input to the collimating lens drive motor driver 25. The collimating lens driving motor driver 25 controls the driving of the collimating lens driving motor 33 by converting the driving instruction signal into an appropriate signal level and inputting it to the collimating lens driving motor 33. Thereby, the collimating lens 26 moves in the optical axis direction.

  When the collimating lens 26 is movable in the optical axis direction, the light beam transmitted from the semiconductor laser 4 through the collimating lens 26 is changed to a light beam slightly diverged from a parallel light beam, or light slightly converged from a parallel light beam. Or a beam. Thereby, the spherical aberration of the light beam condensed on the optical disk 1 can be corrected.

  On the other hand, as shown in FIG. 4, the tracking servo various compensation circuit 47 generates a drive instruction signal for driving the tracking coil 56 of the actuator 3 based on the tracking error signal. At this time, the tracking servo compensation circuit 47 performs various compensations in order to drive the tracking coil 56 optimally. As an example of this compensation, there is a phase compensation for preventing oscillation due to the positive feedback of the phase of the control system exceeding 180 degrees.

  The track jump control circuit 48 generates a drive instruction signal for moving the objective lens 2 from a reference position before operation to a position where tracking servo is performed.

  The switch SW6 switches between a drive instruction signal from the tracking servo compensation circuit 47 and a drive instruction signal from the track jump control circuit 48 based on an instruction from the servo controller 40. The switch SW5 selects whether or not to send a drive instruction signal from the tracking servo compensation circuit 47 or the track jump control circuit 48 to the actuator driver 13 based on an instruction from the servo controller 40. The tracking servo is turned on / off by the switch SW5.

  A drive instruction signal from the tracking servo compensation circuit 47 or the track jump control circuit 48 via the switch SW6 and the switch SW5 is converted into an analog signal by the D / A converter 54, and then is used for tracking of the actuator driver 13. Input to the driver 55. The tracking driver 55 controls the drive of the tracking coil 56 by converting the drive instruction signal into an appropriate signal level and inputting it to the tracking coil 56. Thereby, the objective lens 2 can be moved to a desired position in the radial direction.

[Embodiment 1]
Next, an embodiment of the present invention will be described with reference to FIGS. The servo DSP 16 of the optical disc recording / reproducing apparatus 30 of the present embodiment operates the spherical aberration servo when the distance from the reference position of the collimating lens 26 to the current position is within a predetermined range. Further, the servo DSP 16 of the optical disc recording / reproducing apparatus 30 of this embodiment operates the spherical aberration servo so that the collimating lens 26 is moved by one step based on the magnitude of the aberration error signal with respect to the target value.

  FIG. 5 shows a schematic configuration of the servo controller 40 in the servo DSP 16. As illustrated, the servo controller 40 includes an aberration error signal acquisition unit 100, a count acquisition unit 101, and an aberration correction control unit 102.

  The aberration error signal acquisition unit 100 acquires an aberration error signal from the error signal generation circuit 41. The aberration error signal acquisition unit 100 transmits the acquired aberration error signal to the aberration correction control unit 102.

  The count acquisition unit 101 acquires a count value from the position pulse counter 103 of the stepping motor control circuit 46. This count value corresponds to the distance from the initial position to the current position in the stepping motor 33. The count acquisition unit 101 transmits the acquired count value information to the aberration correction control unit 102.

  The aberration correction control unit 102 instructs the various aberration servo compensation circuits 44 to perform appropriate aberration correction based on the aberration error signal acquired from the aberration error signal acquisition unit 100 and the count value information acquired from the count acquisition unit 101. To do. Specifically, the aberration correction control unit 102 transmits an instruction based on the aberration error signal to the various aberration servo compensation circuits 44 when the count value is within a predetermined range. The details will be described with reference to FIG.

  FIG. 6 shows an example of the correspondence between the position of the collimating lens and the aberration error signal (spherical aberration signal). In FIG. 6, the position of the collimating lens 26 is indicated by the count value of the position pulse counter 103. The aberration error signal is indicated by a voltage value.

  In FIG. 6, the home position corresponds to the reference position, and is a position where the collimating lens 26 is moved in advance before the servo DSP 16 starts correcting the spherical aberration. The end position is the farthest position that can be moved when the collimating lens 26 is moved from the home position to the optical disc 1 side. Normally, an end sensor is provided at this position. When the end sensor detects that the collimating lens 26 has reached the end position, the servo DSP 16 controls the stepping motor 33 to stop the movement of the collimating lens 26. Thereby, it is possible to prevent the collimating lens 26 from moving from the end position toward the optical disc 1 and colliding with other optical elements.

  In the graph shown in FIG. 6, the aberration error signal decreases near the home position with respect to an ideal S-shaped curve. The target value of the aberration error signal is 0.2V. If the aberration error signal is above the target value, the aberration correction control unit 102 moves the collimating lens 26 to the end position side, and if the aberration error signal is below the target value, the aberration correction control unit 102 moves the aberration to the home position side. It instructs the servo various compensation circuit 44.

  Therefore, in the graph shown in FIG. 6, in the range 111 where the count value of the position pulse counter 110 (the position of the collimating lens 26) is larger than about 25 and smaller than about 105, the collimating lens 26 is driven to the end position side. In a range 112 greater than about 105, the collimating lens 26 is moved to the home position side. For this reason, in the ranges 111 and 112 where the count value is greater than about 25, the collimating lens 26 moves toward the target position.

  On the other hand, in the range 110 where the count value is less than about 25, the collimating lens 26 is moved to the home position side. For this reason, the collimating lens 26 moves from the target position to the opposite side, and the spherical aberration cannot be corrected. In the worst case, the collimating lens 26 may collide with other members and be damaged.

  Therefore, in this embodiment, when the collimating lens 26 is moved to a position corresponding to the recording layer to be condensed, and the count value of the position pulse counter 110 is within a range 111/112 larger than about 25, spherical aberration is obtained. The aberration correction control unit 102 instructs the aberration servo compensation circuit 44 to operate the servo. Thereby, when the count value is smaller than about 25, the movement control of the collimating lens 26 based on the aberration error signal can be stopped. As a result, erroneous control of spherical aberration correction can be prevented.

  In the present embodiment, the aberration correction control unit 102 prevents the aberration servo compensation circuit 44 from giving an instruction to deviate from the above ranges 111 and 112 during the spherical aberration servo operation. . Thus, the count value does not deviate from the above ranges 111 and 112 while the movement control of the collimating lens 26 based on the aberration error signal is being performed. Therefore, erroneous control of spherical aberration correction can be reliably prevented.

  Note that the range of the count value is fixed in the range 111 and 112 larger than about 25. However, since the thickness of the cover layer varies among the optical discs 1, it is preferable to change the range of the count value in accordance with the variation.

  Therefore, the range of the count value is preferably a range in which the value of the aberration error signal is monotonously decreasing with respect to the count value, that is, a range greater than about 75 in the example of FIG. In this range, correction of spherical aberration based on the aberration error signal can be performed appropriately, so that erroneous control of correction of spherical aberration can be reliably prevented.

  Further, the range of the count value is preferably such that the median value is a count value when the value of the aberration error signal is equal to the target value of the aberration servo. That is, in the example of FIG. 6, the range of the count value is preferably a range 113 that is greater than about 75 and less than about 125. In this case, in the count value range, the magnitude of the range in which the value of the aberration error signal is larger than the target value is approximately the same as the magnitude of the range in which the value of the aberration error signal is smaller than the target value. .

  For example, in the case of spherical aberration due to the thickness of the cover layer of the optical disk, since the optical disk rotates, the time-series waveform of the aberration error signal becomes a waveform that vibrates from the target value. Therefore, when the value of the aberration error signal deviates greatly from the target value, it is considered that some disturbance has occurred. In such a case, the collimating lens driving mechanism 27 is not controlled based on the aberration error signal, thereby preventing the spherical surface. It is possible to more reliably prevent erroneous control of aberration correction.

  The width of the range 113 may be fixed. However, the change in the value of the aberration error signal with respect to the count value of the position pulse counter 110 may vary among the optical pickups 7. Therefore, the width of the range 113 is preferably variable. The width of the range 113 may be fixed after the optical pickup 7 is incorporated in the optical disc recording / reproducing apparatus 30.

  Next, processing for controlling driving of the collimating lens 26 in the optical disc recording / reproducing apparatus 30 having the above-described configuration will be described with reference to FIGS. FIG. 7 shows a process flow until the collimating lens (CL) 26 is moved to a position corresponding to the recording layer selected by the system controller 18. FIG. 8 shows a flow of processing of the spherical aberration servo performed after the processing shown in FIG.

  As shown in FIG. 7, first, the stepping motor control circuit 46 moves the collimating lens 26 to the home position (reference position) (S100). When the movement is completed, the stepping motor control circuit 46 initializes a pulse counter (CL position pulse counter) 103 indicating the CL position (S101). As a result, the count value of the CL position pulse counter 103 (hereinafter referred to as “CL movement count value”) becomes zero.

  Next, the servo controller 40 determines the recording layer to which the focus is drawn (S102), and instructs the jump control circuit 45 to move the collimating lens 26 to a position corresponding to the determined recording layer (S103 / S104). . The servo controller 40 instructs the switch SW4 to switch to the jump control circuit 45 and turn on the switch SW3. As a result, the stepping motor control circuit 46 instructs the stepping motor 33 to move stepwise to the position indicated by the jump control circuit 45. Further, the stepping motor control circuit 46 updates the count value of the position pulse counter in response to the movement instruction (S103 / S104).

  Next, the servo controller 40 instructs the start of focus servo pull-in (S105). When the focus servo pull-in is completed (S106), the aberration correction control unit 102 of the servo controller 40 has a CL movement count value acquired from the stepping motor control circuit 46 via the count acquisition unit 101 greater than 75 and greater than 125. Is determined to be within a small range (hereinafter referred to as “servo optimum range”) (S107).

  If the CL movement count value does not exist within the servo optimum range (NO in S107), it is determined that the collimating lens 26 has not moved to an appropriate area where spherical aberration servo is performed, and known error processing is performed. On the other hand, when the CL movement count value is within the servo optimum range (YES in S107), the operation of the spherical aberration servo is started.

  When the operation of the spherical aberration servo is started, first, as shown in FIG. 8, the aberration correction control unit 102 receives the aberration error signal of the spherical aberration acquired from the error signal generation circuit 41 via the aberration error signal acquisition unit 100. Then, it is determined whether or not the target value is exceeded (S110).

  When the aberration error signal is less than the target value (NO in S110), the aberration correction control unit 102 subtracts 1 from the CL movement count value acquired from the stepping motor control circuit 46 via the count acquisition unit 101. It is determined whether or not the value is within the servo optimum range (S111). When the value obtained by subtracting 1 from the CL movement count value does not exist within the servo optimum range (NO in S111), the aberration correction control unit 102 tries to move the collimating lens 26 outside an appropriate region for performing the spherical aberration servo. It returns to step S110. That is, the aberration correction control unit 102 prevents the movement of the collimating lens 26.

  On the other hand, when the value obtained by subtracting 1 from the CL movement count value is within the servo optimum range (YES in S111), the aberration correction control unit 102 determines that the collimating lens 26 is in an appropriate region for performing spherical aberration servo. If it is determined that it is going to move, the stepping motor control circuit 46 is instructed via the aberration servo compensation circuit 44, and the collimator lens 26 is moved one step in the home position direction (S112). At this time, the stepping motor control circuit 46 subtracts 1 from the count value of the position pulse counter 103 (S113). Then, it returns to step S110 and repeats the said operation | movement.

  On the other hand, if the aberration error signal is equal to or greater than the target value in step S110 (YES in S110), the aberration correction control unit 102 determines that the value obtained by adding 1 to the CL movement count value is within the servo optimum range. It is determined whether or not it exists inside (S114). When the value obtained by adding 1 to the CL movement count value does not exist within the servo optimum range (NO in S114), the aberration correction control unit 102 tries to move the collimating lens 26 outside an appropriate region where the spherical aberration servo is performed. It returns to step S110. That is, the aberration correction control unit 102 prevents the movement of the collimating lens 26.

  On the other hand, when the value obtained by adding 1 to the CL movement count value is within the servo optimum range (YES in S114), the aberration correction control unit 102 determines that the collimating lens 26 is in an appropriate region for performing the spherical aberration servo. If it is determined that it is going to move, the stepping motor control circuit 46 is instructed via the aberration servo compensation circuit 44, and the collimating lens 26 is moved one step in the end position direction (S115). At this time, the stepping motor control circuit 46 adds 1 to the count value of the position pulse counter 103 (S116). Then, it returns to step S110 and repeats the said operation | movement.

  As described above, in the present embodiment, the aberration correction control unit 102 instructs the aberration servo compensation circuit 44 to change the collimator lens 26 by one step based on the magnitude of the aberration error signal with respect to the target value. . Thereby, the collimating lens 26 is changed by one step regardless of the magnitude of the difference of the aberration error signal with respect to the target value, so that the collimating lens 26 does not change greatly even if the magnitude of the difference is large. Therefore, since the change of the collimating lens 26 can be suppressed, the power consumption required by the stepping motor 33 for changing the collimating lens 26 can be suppressed.

  In this embodiment, the optical disk 1 having the two recording layers L0 and L1 has been described. However, the present invention can also be applied to the optical disk 1 having one recording layer, and the optical disk 1 having three or more recording layers. Is also applicable.

  In this embodiment, the aberration correction control unit 102 instructs the steps S112 and S115. However, the various aberration servo compensation circuits 44 may perform the instructions. In this case, the aberration correction control unit 102 performs the determination processing in steps S110, S111, and S114, and when the determination in steps S111 and S114 is NO, the aberration servo compensation circuit 44, the stepping motor control circuit 46, or the switch SW3. It is sufficient to instruct to stop the control of the aberration servo.

[Embodiment 2]
Next, another embodiment of the present invention will be described with reference to FIGS. The servo DSP 16 of the optical disc recording / reproducing apparatus 30 of this embodiment starts the movement of the collimating lens 26 toward a position corresponding to a recording layer to be accessed (hereinafter referred to as “access target layer”). The focus servo control is executed, and the spherical aberration servo control is executed. In addition, the same code | symbol is attached | subjected to the structure which has the function similar to the structure demonstrated in the said embodiment, and the description is abbreviate | omitted.

  In this embodiment, the optical disk 1 having two recording layers L0 and L1 is used. However, the present invention can be applied to the optical disk 1 having one recording layer, and the optical disk 1 having three or more recording layers. Is also applicable. Hereinafter, the two recording layers are referred to as a first recording layer L0 and a second recording layer L1 from the optical pickup 7 side (the surface side of the optical disc 1).

  FIG. 9 shows a schematic configuration of the servo controller 40 in the servo DSP 16 of the optical disc recording / reproducing apparatus 30 of the present embodiment. As shown in FIG. 9, the servo controller 40 includes a count acquisition unit 101, a target count value storage unit 200, a target position arrival detection unit 201, an intermediate position arrival detection unit 202, an access target layer acquisition unit 203, and an aberration correction control unit. 204 and a focus control unit 205.

  The count acquisition unit 101 acquires a count value from the position pulse counter 103 of the stepping motor control circuit 46. This count value corresponds to the distance from the reference position to the current position in the stepping motor 33. The count acquisition unit 101 transmits the acquired count value information to the target position arrival detection unit 201 and the intermediate position arrival detection unit 202.

  The target count value storage unit 200 stores a count value (hereinafter referred to as “target count value”) corresponding to a position (hereinafter referred to as “target position”) that is a movement target of the collimating lens 26. The target count value storage unit 200 is configured by a rewritable nonvolatile memory such as a flash memory, for example.

  In the present embodiment, the target count value storage unit 200 stores target count values corresponding to the target positions of the recording layers L0 and L1. These target positions may be optimal aberration correction positions that optimally correct spherical aberration in each recording layer, but are preferably aberration correctable positions that enable correction of spherical aberration by the aberration servo. In this case, since the aberration servo can be operated before the collimating lens 26 reaches the aberration correction optimum position, the access to the optical disc 1 becomes quick.

  When the aberration correctable position is used as the target position, the target position corresponding to the first recording layer L0 of the optical disc 1 is moved to the opposite side when the collimator lens 26 is moved to the optical disc 1 side. It will be different from time to time. Therefore, the target count value storage unit 200 stores two target count values corresponding to the first recording layer L0.

  The target position arrival detection unit 201 detects that the collimator lens 26 has reached the target position corresponding to the access target layer. The target position arrival detection unit 201 notifies the aberration correction control unit 204 of the detection of the arrival.

  Specifically, the target position arrival detection unit 201 first acquires the current count value from the count acquisition unit 101 and acquires the target count value corresponding to the access target layer from the target count value storage unit 200. Then, the target position arrival detection unit 201 detects that the current count value has reached the target count value.

  The intermediate position arrival detection unit 202 is located at an intermediate position between the position of the collimating lens 26 immediately before being driven to the access target layer (hereinafter referred to as “position immediately before driving”) and the target position corresponding to the access target layer. It detects that the collimating lens 26 has arrived. The intermediate position arrival detection unit 202 notifies the focus control unit 205 of the detection of the arrival.

  Specifically, the intermediate position arrival detection unit 202 first acquires from the count acquisition unit 101 a count value corresponding to the position immediately before driving (hereinafter referred to as “count value immediately before driving”) and the current count value. At the same time, the target count value corresponding to the access target layer is acquired from the target count value storage unit 200. The count value immediately before driving may be acquired from the count acquisition unit 101 when the aberration correction control unit 204 instructs driving of the collimating lens 26 to the access target layer. Then, the intermediate position arrival detection unit 202 detects that the current count value has reached an intermediate value between the count value immediately before driving and the target count value.

  The information on the access target layer may be acquired from the aberration correction control unit 204 or may be acquired from the access target layer acquisition unit 203. Further, the target position arrival detection unit 201 and the intermediate position arrival detection unit 202 can also use the difference of the target count value with respect to the count value immediately before driving. Specifically, the target position arrival detection unit 201 increases or decreases the difference by 1 each time the count value acquired by the count acquisition unit 101 increases or decreases by 1 and indicates that the difference has reached zero. What is necessary is just to detect. Similarly, the intermediate position arrival detection unit 202 may detect that the difference has reached half of the original value.

  The access target layer acquisition unit 203 acquires information on the access target layer from the system controller 18. The access target layer acquisition unit 203 transmits information on the access target layer to the aberration correction control unit 204 and the focus control unit 205.

  The aberration correction control unit 201 instructs the switches SW3 and SW4 and the aberration servo compensation circuit 44 to move the collimating lens 26 to correct the spherical aberration.

  Specifically, when the aberration correction control unit 201 needs to move the collimator lens 26 based on the information of the access target layer acquired from the access target layer acquisition unit 203, first, the aberration correction control unit 201 is directed toward a position corresponding to the access target layer. The collimating lens 26 is driven. Next, when the arrival at the target position is notified from the target position arrival detection unit 201, the aberration correction control unit 201 moves the collimating lens 26 based on the aberration error signal. As a result, the collimating lens 26 follows the position for correcting the spherical aberration corresponding to the access target layer.

  According to the above configuration, the collimating lens 26 can be moved without referring to the aberration error signal until it reaches the target position. Therefore, the collimating lens 26 can be moved at high speed.

  The focus control unit 202 instructs the switches SW1 and SW2 and the focus servo compensation circuit 42 to change the focus position in the normal direction of the optical disc 1.

  Specifically, the focus control unit 205 reaches the intermediate position from the intermediate position arrival detection unit 202 when it is necessary to move the objective lens 2 based on the access target layer information acquired from the access target layer acquisition unit 203. Is notified, the objective lens 2 is moved to a position corresponding to the access target layer. Thereby, the objective lens 2 is moved in a state where the spherical aberration corresponding to the access target layer is corrected to some extent, so that the focus can be reliably drawn into the access target layer.

  Next, processing for controlling the optical pickup 7 of the optical disc recording / reproducing apparatus 30 having the above-described configuration will be described with reference to FIGS. FIG. 10 shows a flow of processing until the optical pickup 7 can access the recording layer (access target layer) instructed by the system controller 18 when the optical disc recording / reproducing apparatus 30 is started up or when the optical disc 1 is loaded. Is shown.

  As shown in FIG. 10, first, the stepping motor control circuit 46 moves the collimating lens 26 to the home position (reference position) (S200). When the movement is completed, the stepping motor control circuit 46 initializes a CL position pulse counter indicating the CL position (S201). As a result, the CL movement count value becomes zero.

  Next, the aberration correction control unit 204 instructs the jump control circuit 45 to move the collimating lens 26 toward the position corresponding to the recording layer that draws focus, that is, the access target layer, and performs jump control on the switch SW4. An instruction is given to switch to the circuit 45 side and to turn on the switch SW3 (S202 to S204). Further, the stepping motor control circuit 46 transmits a pulse signal to the stepping motor 33 and updates the count value of the position pulse counter based on the signal from the jump control circuit 45 (S203 and S204).

  Next, when the intermediate position arrival detection unit 202 detects that the current CL movement count value has reached the intermediate value between the count value immediately before driving and the target count value (S205), the focus control unit 205 starts pulling in the focus servo. (S206).

  That is, the focus control unit 205 instructs the ramp circuit 43 to move the objective lens 2 toward the position corresponding to the recording layer that draws focus, that is, the access target layer, and sets the switch SW2 to the ramp circuit 43 side. And instruct to turn on the switch SW1. When the movement of the objective lens is completed, the focus control unit 205 switches the switch SW2 to the focus servo various compensation circuit 42 side so that the focus position follows the access target layer. In the example of FIG. 10, the count value immediately before driving becomes zero in step S201, and therefore, in step S205, the intermediate position arrival detection unit 202 detects that it has reached half of the target count value. .

  After the focus servo pull-in is completed (S207), when the target position arrival detection unit 201 detects that the current CL movement count value has reached the target count value (S208), the aberration correction control unit 204 sets the switch SW4. The aberration servo is operated (turned on) by switching to the aberration servo compensation circuit 44 side (S209). When the aberration error signal crosses zero (S210), the servo controller 40 forms a tracking servo loop and a thread servo loop, and operates the tracking servo and the thread servo (S211). As a result, the optical pickup 7 can access the access target layer.

  FIG. 11 shows the flow of processing of the aberration servo. As shown in the figure, first, the various aberration servo compensation circuits 44 determine whether or not the spherical aberration aberration error signal acquired from the error signal generation circuit 41 is equal to or greater than zero (S220). When the aberration error signal is less than zero (NO in S220), the aberration servo compensation circuit 44 instructs the stepping motor control circuit 46 to move the collimating lens 26 one step in the home position direction (S221). At this time, the stepping motor control circuit 46 subtracts 1 from the count value of the position pulse counter 103 (S222). Then, it returns to step S220 and repeats the said operation | movement.

  On the other hand, if the aberration error signal is greater than or equal to zero in step S220 (YES in S220), the various aberration servo compensation circuit 44 instructs the stepping motor control circuit 46 to move the collimating lens 26 toward the end position. Step movement is performed (S223). At this time, the stepping motor control circuit 46 adds 1 to the count value of the position pulse counter 103 (S224). Then, it returns to step S220 and repeats the said operation | movement.

  Therefore, in the present embodiment, the various aberration servo compensation circuits 44 instruct the stepping motor control circuit 46 to change the collimating lens 26 by one step based on the sign of the aberration error signal. As a result, the collimating lens 26 is changed by one step regardless of the magnitude of the aberration error signal, so that the collimating lens 26 is not greatly changed even if the magnitude of the aberration error signal is large. Therefore, since the change of the collimating lens 26 can be suppressed, the power consumption required by the stepping motor 33 for changing the collimating lens 26 can be suppressed.

  Further, since the count value of the position pulse counter 103 is changed according to the movement of the collimating lens 26, the current position of the collimating lens 26 can be grasped from the count value.

  FIG. 12 shows the flow of processing (interlayer jump processing) until an optical pickup that can access a certain recording layer becomes accessible to another recording layer in accordance with an instruction from the system controller 18. As shown in the figure, first, the servo controller 40 performs control so that the sled servo, tracking servo, and aberration servo are turned off (S230). Note that the focus servo remains on.

  Next, the aberration correction control unit 204 determines which recording layer is jumped to which recording layer (S231). Based on this determination, the aberration correction control unit 204 performs various aberration servo compensation circuits so that the collimator lens 26 moves from the position corresponding to the jump source recording layer to the position corresponding to the jump destination recording layer. 44, the switch SW4 is set to the aberration servo compensation circuit 44 side, and the switch SW3 is instructed to be turned on (S232, S233). In other words, the aberration servo compensation circuit 44 does not perform a servo operation based on the aberration error signal, but instructs the stepping motor control circuit 46 to move the collimator lens 26 in one direction.

  Further, the stepping motor control circuit 46 transmits a pulse signal to the stepping motor 33 and updates the count value of the position pulse counter based on the signal from the various aberration servo compensation circuits 44 (S232, S233).

  Next, when the intermediate position arrival detection unit 202 detects that the current CL movement count value has reached the intermediate value between the count value immediately before driving and the target count value (S234), the focus control unit 205 reads the target recording layer ( The focus servo various compensation circuits 42 are instructed to perform a focus jump to the access target layer (S235). At this time, since the focus servo remains on, the switch SW2 is on the focus servo various compensation circuit 42 side, and the switch SW1 is on. Therefore, the objective lens 2 performs a focus jump according to an instruction from the focus servo compensation circuit 42.

  When the focus jump of the objective lens 2 is completed (S236), the focus control unit 205 instructs the focus servo various compensation circuits 42 to operate the focus servo again. Thereby, the focal position can be made to follow the access target layer of the jump destination.

  Next, when the target position arrival detection unit 201 detects that the current CL movement count value has reached the target count value (S237), the aberration correction control unit 204 causes the aberration servo various compensation circuits 44 to operate the aberration servo. (S238). When the aberration error signal crosses zero (S239), the servo controller 40 forms a tracking servo loop and a thread servo loop, and operates the tracking servo and the thread servo (S240). As a result, the optical pickup 7 can access the jump target access target layer.

  FIG. 13 shows temporal changes of various signals when an interlayer jump process from the second recording layer L1 to the first recording layer L0 is performed in the optical disc recording / reproducing apparatus 30 configured as described above. FIG. 14 shows an enlarged period for performing the focus jump in FIG.

  The signals shown in FIGS. 13 and 14 are a focus error signal (FES), a collimating lens driving pulse signal (CL driving monitor), a tracking error signal (DPD), and a sense signal (SENSE) in order from the top. The collimating lens driving pulse signal is a pulse signal output from the stepping motor control circuit 46 to the stepping motor 33 in order to drive the collimating lens 26. The sense signal is a signal indicating whether the servo DSP 16 accepts an instruction from the outside (for example, the system controller 18). When the sense signal is at the H level, the servo DSP 16 does not accept an instruction from the outside. In the illustrated example, the period during which the sense signal is at the H level is a period during which the interlayer jump process shown in FIG. 12 is performed.

  As shown in FIG. 13, when driving is started at time T200, the collimating lens 26 moves at high speed (coarse movement) to the target position, and after reaching the target position at time T202, an aberration error occurs. It moves at a low speed (fine movement) based on the signal. In the illustrated example, the number of pulses input to the stepping motor 33 in order for the collimating lens 26 to move from the position immediately before driving to the target position is 76.

  At time T201, when the 38th pulse is input to the stepping motor 33 and the collimating lens 26 reaches a half distance to the target position, a focus jump is performed. As shown in FIG. 14, the focus jump ends at time T204 when the focus error signal vibrates once in the vertical direction. Thereafter, the focus error signal converges to 0 level by the focus servo.

  On the other hand, FIGS. 15 and 16 are comparative examples corresponding to FIGS. 13 and 14, respectively, and show a case where the objective lens 2 is moved at the same time as the collimator lens 26 is moved at time T210. As shown in FIG. 16, the focus jump starts at time T210 and ends at time T213 when the focus error signal vibrates once up and down.

  Comparing FIG. 14 and FIG. 16, it can be understood that the focus error signal converges more quickly in the present embodiment than in the comparative example. In the case of the comparative example, the focus error signal sometimes oscillates without converging and loses focus.

  In this embodiment, the focus control unit 205 moves the objective lens 2 when the collimating lens 26 reaches an intermediate point between the position immediately before driving and the target position. However, if the sensitivity of the focus error signal can be obtained to such an extent that the focus can be surely pulled, the objective lens 2 may be moved when an arbitrary position between the position immediately before driving and the target position is reached. .

  In the present embodiment, the focus control unit 205 uses the position (counter value) of the collimator lens 26 as a trigger for starting driving. However, as described in an embodiment described later, the magnitude of the aberration error signal is a predetermined value. When the threshold value is exceeded, a trigger for starting driving can be used.

[Embodiment 3]
Still another embodiment of the present invention will be described with reference to FIGS. 17 to 20B. The servo DSP 16 of the optical disc recording / reproducing apparatus 30 of this embodiment controls to start the tracking follow-up operation when the aberration error signal reaches a predetermined threshold value.

  The configuration other than that described in the present embodiment is the same as the configuration of the optical disc recording / reproducing apparatus common to the above-described embodiments. For convenience of explanation, members having the same functions as those shown in the drawings used for explaining the configuration of the optical disc recording / reproducing apparatus common to the embodiments are given the same reference numerals, and explanation thereof is omitted. .

  FIG. 17 is a functional block diagram of the servo controller 40. FIG. 18 is a graph showing the threshold value of the aberration error signal necessary for drawing the tracking servo (starting the tracking follow-up operation). FIG. 20 (a) and 20 (b) are diagrams showing the completion time of the interlayer jump by the conventional optical disc apparatus and the optical disc recording / reproducing apparatus of the present invention, respectively. .

  First, the configuration of the servo controller 40 will be described.

  The servo controller 40 is provided in the servo DSP 16 and includes a storage unit 301 and a calculation unit 302 as shown in FIG.

  The storage unit 301 stores in advance a threshold value of the spherical aberration error voltage necessary for pulling in the tracking servo.

  As shown in FIG. 18, the threshold value represents the value of the spherical aberration error signal corresponding to the voltage level of the tracking error signal having a magnitude necessary for pulling in the tracking servo. Then, the value of the spherical aberration error signal (spherical aberration signal) corresponding to the voltage level of the tracking error signal having a magnitude necessary for drawing the tracking servo corresponds to the threshold value. Therefore, it can be said that the threshold value is a threshold value of the spherical aberration error signal necessary for pulling in the tracking servo.

  The calculation unit 302 refers to the value of the spherical aberration error voltage (aberration error signal) transmitted from the error signal generation circuit 41 and the correction threshold information stored in the storage unit 301, and performs a predetermined procedure. Is calculated according to Then, the switch 5 is instructed to switch according to the result of the calculation.

  For example, the calculation unit 302 compares the value of the aberration error signal with the threshold value. When the value of the aberration error signal has reached the threshold value, a drive instruction signal from the tracking servo various compensation circuit (tracking tracking means) 47 or the track jump control circuit 48 is transmitted to the actuator driver 13. , SW5 is instructed to switch (ON).

  For example, the arithmetic unit 302 compares the value of the aberration error signal with the threshold value. When the value of the aberration error signal does not reach the threshold value, the SW5 is instructed not to transmit a drive instruction signal from the tracking servo compensation circuit 47 or the track jump control circuit 48 to the actuator driver 13. To switch (off).

  The storage unit 301 and the calculation unit 302 are functional blocks that are realized when the CPU executes a program stored in the storage device and controls peripheral circuits such as an input / output circuit (not shown).

  In the present embodiment, the threshold information is stored in the storage unit 301. However, the present invention is not limited to this. For example, the threshold value information is incorporated into a program executed by the calculation unit 302. A configuration without 301 is also possible.

  Further, the threshold value corresponding to the aberration error signal detected for each optical disk 1 may be set for each optical disk 1 every time the optical disk 1 to be recorded or reproduced is switched.

  Subsequently, an operation flow in the optical disc recording / reproducing apparatus 30 of the present embodiment will be described with reference to a flowchart shown in FIG.

  First, an interlayer jump in the optical disc recording / reproducing apparatus 30 is started.

  When the interlayer jump starts, in step S301, the movement of the collimator lens 26 from the information recording layer (L0 layer) to the other information recording layer (L1 layer) (coarse movement of the CL position) starts.

  In step S302, the servo controller 40 observes the spherical aberration error signal (receives the spherical aberration error signal in the storage unit 301 in the servo controller 40). In step S303, it is determined whether or not the position of the collimating lens 26 has reached a substantially intermediate position between the L0 layer and the L1 layer. If the position of the collimating lens 26 has reached the substantially intermediate position between the L0 layer and the L1 layer (Yes in step S303), the process proceeds to step S304. If the position of the collimating lens 26 has not reached the substantially intermediate position between the L0 layer and the L1 layer (No in step S303), the flow of step S303 is repeated.

  In step S304, a focus jump is performed. Subsequently, in step S305, servo control for the collimating lens 26, that is, spherical aberration servo is started. In step S306, the calculation unit 302 in the servo controller 40 determines whether the level of the spherical aberration error signal has reached a threshold value.

  If the level of the spherical aberration error signal has reached the threshold value (Yes in step S306), the process proceeds to step S307. If the level of the spherical aberration error signal has not reached the threshold (No in step S306), the flow returns to step S306 and the flow is repeated.

  In step S307, the tracking servo is turned on and tracking servo pull-in is started.

  In step S308, the sled servo is turned on and the sled servo operation is started.

  Then, the interlayer jump in the optical disc recording / reproducing apparatus 30 ends.

  In the present embodiment, the configuration in which spherical aberration servo is performed by the optical disc recording / reproducing apparatus 30 at the time of interlayer jump is shown, but the present invention is not necessarily limited to this. For example, the configuration may be such that the spherical aberration servo is performed when the optical disc 1 is displaced due to an impact or the like applied to the optical disc recording / reproducing apparatus 30 even when not in the interlayer jump.

  That is, when the optical disc 1 is displaced from the focal point of the irradiation light with respect to the information recording layer in which the focal point of the irradiation light is located before the impact or the like is applied to the optical disc recording / reproducing apparatus 30, the spherical surface is formed. A configuration in which aberration servo is performed may be used.

  According to the above configuration, when the value of the spherical aberration error signal reaches the threshold value before the time when the value of the spherical aberration error signal reaches the value when the amplitude value of the tracking error signal becomes maximum, the tracking servo is Can be pulled in.

  The time when the amplitude value of the tracking error signal becomes maximum is the time when the servo control in the conventional aberration servo compensation circuit 44 is completed. Therefore, when the value of the spherical aberration signal reaches the threshold value before reaching the value of the spherical aberration error signal at the time when the amplitude value of the tracking error signal becomes the maximum, various conventional aberration servo compensation circuits The time is before the time when the servo control at 44 is completed.

  Also, the servo control by the aberration servo compensation circuit 44 is performed to monitor the level of the spherical aberration error signal corresponding to the amplitude value of the tracking error signal, and when the spherical aberration error signal reaches the above threshold, tracking is performed. The servo various compensation circuit 47 is activated. Therefore, the tracking servo compensation circuit 47 can be operated without monitoring the amplitude value of the tracking error signal by monitoring the level of the spherical aberration error signal while performing servo control by the aberration servo compensation circuit 44. It is configured to be able to.

  Therefore, the threshold value can be set to the value of the spherical aberration error signal when the amplitude value of the tracking error signal is at a level at which the tracking servo compensation circuit 47 can be stably operated. Further, by monitoring the value of the spherical aberration error signal without monitoring the amplitude value of the tracking error signal, it becomes possible to pull in the tracking servo when the tracking servo compensation circuit 47 can be stably operated. Become.

As a result, the time required for the interlayer jump can be shortened. Referring to FIG. 18, the value of the spherical aberration error signal when the voltage level of the tracking error signal is the highest is indicated by point B in FIG. This is the best point for spherical aberration correction (target value of spherical aberration servo). The point B is also a target value for completing the correction of the conventional spherical aberration.

  On the other hand, the threshold value corresponds to the value of the spherical aberration error signal at a time point before reaching point B in the range indicated by point A and point C in FIG. Accordingly, the servo DSP 16 of the present invention starts pulling in the tracking servo on the assumption that the spherical aberration servo is completed at the time point A in FIG. 18 before the point B reaching the target value of the spherical aberration servo. It will be.

  That is, in the optical disc recording / reproducing apparatus 30 of the present invention, the spherical aberration servo is completed earlier than the completion timing of the spherical aberration correction, and the tracking servo pull-in is started.

  Further, the interlayer jump between the case where the interlayer jump is performed while the aberration correction servo is applied by the conventional optical disk recording / reproducing apparatus and the case where the interlayer jump is performed while the aberration correction servo is applied by the optical disk recording / reproducing apparatus 30 of the present invention. The test results obtained by examining the difference in time required for the above will be specifically described with reference to FIGS. 20 (a) and 20 (b).

  FIG. 20A shows a focus error signal, an aberration error signal, and an aberration error signal when an interlayer jump is performed from one information recording layer (L0 layer) to the other information recording layer (L1 layer) by a conventional optical disc recording / reproducing apparatus. It is the figure which showed the signal waveform of a tracking error signal and CL drive pulse.

  FIG. 20B shows a focus error signal when an optical disc recording / reproducing apparatus 30 according to the present invention performs an interlayer jump from one information recording layer (L0 layer) to the other information recording layer (L1 layer). It is the figure which showed the signal waveform of an aberration error signal, a tracking error signal, and CL drive pulse.

  After releasing the tracking servo (opening the tracking servo loop) and releasing the spherical aberration servo (opening the spherical aberration servo loop), the collimating lens is moved from one information recording layer (L0 layer) to the other information recording layer (L1). Layer (coarse movement of CL position) starts, the spherical aberration error signal gradually deviates from the target value (0V) with the movement of the collimating lens from the point when the amplitude of the tracking error signal suddenly increases. Go. Next, when the focus jump is completed, the polarity of the spherical aberration error signal changes, and when the spherical aberration servo is started, the spherical aberration error signal gradually approaches the target value (0 V). The time point when the amplitude of the tracking error signal suddenly decreases represents the time point when the tracking servo is pulled.

  As shown in FIG. 20A, conventionally, tracking servo pull-in is performed when there is almost no fluctuation in the spherical aberration error signal after the spherical aberration servo is started. The time from when the spherical aberration servo was actually started until the tracking servo was pulled in was 74 ms.

  On the other hand, as shown in FIG. 20B, in the case where the optical disk recording / reproducing apparatus 30 of the present invention is used, the tracking servo in the middle of the fluctuation of the spherical aberration error signal after the spherical aberration servo is started. The tracking servo is retracted when it can be retracted. Then, when the time from when the spherical aberration servo was actually started until the tracking servo was pulled in was measured, it was 33 msec. That is, the optical disc recording / reproducing apparatus 30 of the present invention realizes that the time from the start of the spherical aberration servo to the tracking servo pull-in is reduced to less than half compared to the conventional case.

[Embodiment 4]
The following will describe still another embodiment of the present invention with reference to FIG. The configurations other than those described in the present embodiment are the same as those of the optical disc recording / reproducing apparatus common to the above-described embodiments or the above-described embodiments. For convenience of explanation, members having the same functions as those shown in the drawings used in the description of the configuration of the optical disc recording / playback apparatus common to the embodiments are denoted by the same reference numerals. The description is omitted.

  FIG. 21 is a functional block diagram of the servo controller 40. First, the configuration of the servo controller 40 will be described. As shown in FIG. 21, the servo controller 40 includes a storage unit 301, a calculation unit 312, and a total signal acquisition unit 313.

  The calculation unit 312 refers to the aberration error signal transmitted from the error signal generation circuit 41, the threshold information stored in the storage unit 301, and the total signal transmitted from the total signal acquisition unit 313, and performs predetermined processing. The calculation is performed according to the procedure. Then, the switch 5 is instructed to switch according to the result of the calculation.

  The total signal acquisition unit 313 acquires a total signal indicating the total amount of reflected light from the optical disc 1 from the signal processing circuit 17 and transmits it to the calculation unit 312.

  Next, processing in the calculation unit 312 when recording / reproducing with the optical disc recording / reproducing apparatus 30 while switching between two optical discs 1 will be described. In addition, recording and reproduction are performed in the order of the first optical disc 1 and the second optical disc 1.

  When recording / reproducing the first optical disc 1, the arithmetic unit 312 corrects the value of the aberration error signal according to the total signal of the first optical disc 1 acquired by the total signal acquisition unit 313. Then, the corrected aberration error signal is compared with the threshold value. Subsequently, when the value of the corrected aberration error signal has reached the threshold value, a drive instruction signal from the tracking servo compensation circuit 47 or the track jump control circuit 48 is transmitted to the actuator driver 13. A switch (ON) instruction is given to SW5.

  Further, when the value of the corrected aberration error signal does not reach the threshold value, a drive instruction signal from the tracking servo various compensation circuit 47 or the track jump control circuit 48 is not transmitted to the actuator driver 13. A switch (OFF) instruction is given to SW5.

  When recording / reproduction of the second optical disc 1 is performed following recording / reproduction of the first optical disc 1, the arithmetic unit 312 generates an aberration error signal according to the total signal of the second optical disc 1 acquired by the total signal acquisition unit 313. Correct the value. Then, the corrected aberration error signal is compared with the threshold value. Subsequently, when the value of the corrected aberration error signal has reached the threshold value, a drive instruction signal from the tracking servo compensation circuit 47 or the track jump control circuit 48 is transmitted to the actuator driver 13. A switch (ON) instruction is given to SW5.

  Further, when the value of the corrected aberration error signal does not reach the threshold value, a drive instruction signal from the tracking servo various compensation circuit 47 or the track jump control circuit 48 is not transmitted to the actuator driver 13. A switch (OFF) instruction is given to SW5.

  Since the aberration error signal is obtained from part of the reflected light from the optical disk 1, the value of the aberration error signal is proportional to the signal from the reflected light of the optical disk, that is, the value of the total signal. Therefore, each time the optical disk 1 to be recorded / reproduced is switched, the aberration error signal is corrected based on the total signal acquired by the total signal acquisition unit 313, thereby correcting the aberration error signal corresponding to each of the two optical disks 1. It becomes possible. And the aberration error signal for every two optical disks 1 becomes uniform. Therefore, the servo DSP 16 can control the actuator driver 13 at a timing corresponding to each of the two optical disks 1.

  The storage unit 301, the calculation unit 312 and the total signal acquisition unit 313 are functional blocks realized by the CPU executing a program stored in the storage device and controlling peripheral circuits such as an input / output circuit (not shown). .

  In the present embodiment, the threshold information is stored in the storage unit 301. However, the present invention is not necessarily limited to this. For example, the threshold information is incorporated into a program executed by the calculation unit 312. It is also possible to adopt a configuration not stored in 301.

  In the present embodiment, the aberration error signal is corrected by the calculation unit 312 based on the total signal acquired by the total signal acquisition unit 313. However, the present invention is not limited to this. For example, the total signal acquisition unit The calculation unit 312 may correct the threshold based on the total signal acquired in 313. The same applies when switching between three or more optical disks 1.

[Embodiment 5]
The following will describe still another embodiment of the present invention with reference to FIGS. The servo DSP 16 of the optical disc recording / reproducing apparatus 30 of this embodiment starts the movement of the collimator lens 26 toward the position corresponding to the access target layer, and controls the focus servo when the aberration error signal reaches a predetermined threshold value. Is executed, and then the control of the spherical aberration servo is executed.

  The configuration other than that described in the present embodiment is the same as the configuration of the optical disc recording / reproducing apparatus common to the above-described embodiments. For convenience of explanation, members having the same functions as those shown in the drawings used for explaining the configuration of the optical disc recording / reproducing apparatus common to the embodiments are given the same reference numerals, and explanation thereof is omitted. .

  First, the configuration of the servo controller 40 will be described with reference to FIG.

  The servo controller 40 includes a storage unit 401 and a calculation unit 402 as shown in FIG.

  The storage unit 401 stores in advance a value (threshold value) of an aberration error signal necessary for drawing the focus servo (operating the focus servo various compensation circuits 42 stably). The threshold value is a value of an aberration error signal corresponding to the value of the focus servo gain as the gain ratio necessary for pulling in the focus servo, and will be described in detail later.

  The computing unit 402 refers to the value of the aberration error signal transmitted from the error signal generation circuit 41 and the threshold value stored in the storage unit 401, and performs computation according to a predetermined procedure. Then, according to the result of the above calculation, the focus servo various compensation circuit 42 is instructed to drive the actuator driver 13 to perform the focus jump.

  For example, the calculation unit 402 compares the value of the aberration error signal with the threshold value. If the value of the aberration error signal has reached the threshold value, the focus servo various compensation circuit 42 is instructed to drive the actuator driver 13 to perform the focus jump. As a result, focus control such as focus jump is performed.

  Further, the calculation unit 402 compares, for example, the value of the aberration error signal with the threshold value. When the value of the aberration error signal does not reach the threshold value, the focus servo compensation circuit 42 is instructed not to drive the actuator driver 13 to perform the focus jump.

  The storage unit 401 and the calculation unit 402 are functional blocks that are realized by the CPU executing a program stored in the storage device and controlling peripheral circuits such as an input / output circuit (not shown).

  In the present embodiment, the threshold information is stored in the storage unit 401. However, the present invention is not limited to this. For example, the threshold value information is incorporated into a program executed by the calculation unit 402. A configuration without 401 may be employed.

  Further, the threshold value corresponding to the aberration error signal detected for each optical disk 1 may be set for each optical disk 1 every time the optical disk 1 to be recorded or reproduced is switched.

  Next, the focus jump timing when performing an interlayer jump in the optical disc 1 having a plurality of recording layers will be described with reference to FIGS. 23, 24 and 27. FIG.

  The interlayer jump here refers to an operation of changing the recording layer for recording or reproduction on the optical disc. Further, the focus jump is an operation during the process of the interlayer jump, and indicates an operation of moving the focus position of the light irradiated from the condensing optical system from one recording layer to the other recording layer. .

  FIG. 23 schematically shows changes in aberration error signals when a focus jump is performed from one recording layer (L0 layer) to the other recording layer (L1 layer) of the optical disc 1. In FIG. 23, the position of the collimating lens (CL) 26 when the focus is on the L0 layer is represented as L0, and the position of the CL26 when the focus is on the L1 layer is represented as L1. The distance from L0 to L1 is about 25 μm as an example. The change of the aberration error signal when the CL 26 is driven from the semiconductor laser (LD) 4 side to the objective lens (OL) 2 side when the focus is on the L0 layer or the L1 layer is indicated by a broken line.

  A case where a focus jump is performed from the L0 layer to the L1 layer will be described as an example. In FIG. 23, it is assumed that the focus jump is performed when CL26 is positioned at an intermediate point between L0 and L1. That is, the threshold corresponding to the voltage corresponding to the aberration error signal when the CL 26 that is in focus on the L0 layer is located at a position of 12.5 μm, which is an intermediate point between L0 and L1.

  First, when the L0 layer is in focus and aberration correction for the L0 layer has been completed, the aberration error signal becomes 0 at the position of L0 as shown in FIG. Subsequently, as the CL 26 is driven from the position L0 to the OL2 side, the absolute value of the aberration error signal increases unless the aberration servo is applied. Then, when the threshold value for starting the focus jump is reached, the focus jump is performed, and the focus moves to the L1 layer. Immediately after the focus moves to the L1 layer, since the spherical aberration does not perfectly match the L1 layer, the absolute value of the aberration error signal becomes larger than 0 as shown in FIG. After that, by applying focus servo and spherical aberration servo, the aberration error signal becomes 0 as shown in L1, the L1 layer is in focus, and the aberration correction for the L1 layer is also completed. .

  FIGS. 24A to 24C show changes in the focus error signal, aberration error signal, and RF signal actually measured when the focus jump is performed.

  FIGS. 24A and 24B are diagrams when a focus jump is performed from the L0 layer to the L1 layer, and FIG. 24B illustrates the period during which the focus jump is performed in FIG. It is expanded to. FIG. 24C is a diagram when a focus jump is performed from the L1 layer to the L0 layer.

  As shown in FIGS. 24A to 24C, a change similar to the change of the aberration error signal accompanying the focus jump represented by the thick line in FIG. 23 is actually recognized. The focus jump ends when the focus error signal vibrates once in the vertical direction. Thereafter, the focus error signal converges to 0 level by the focus servo. Accordingly, in FIGS. 24A to 24C, the vibration of the focus error signal is detected only once for one focus jump, which means that the focus error signal converges quickly after the focus jump. Means that

  Next, an operation flow in the optical disc recording / reproducing apparatus 30 according to the present embodiment will be described with reference to flowcharts shown in FIGS.

  First, FIG. 25 shows an operation flow in the optical disc recording / reproducing apparatus 30 in the case where the CL 26 is driven by the number of pulses corresponding to the distance between the recording layers where the focus jump is performed during the interlayer jump.

  First, an interlayer jump in the optical disc recording / reproducing apparatus 30 is started. When the interlayer jump starts, in step S401, the thread servo, tracking servo, and aberration servo are turned off.

  Subsequently, in step S402, it is determined whether the focus jump is performed from the L0 layer to the L1 layer or from the L1 layer to the L0 layer by the servo DSP 16. If it is determined that the focus jump is performed from the L0 layer to the L1 layer (L0 → L1 in step S402), the process proceeds to step S403, and the number of pulses corresponding to the distance from the L0 layer to the L1 layer is set. The driving of the CL 26 to the OL2 side is started. Then, the process proceeds to step S404.

  If it is determined that the focus jump is performed from the L1 layer to the L0 layer (L1 → L0 in step S402), the process proceeds to step S411, and the number of pulses corresponding to the distance from the L1 layer to the L0 layer is set. The driving of the CL 26 to the LD4 side is started. Then, the process proceeds to step S412.

  Subsequently, in step S404, the calculation unit 402 in the servo controller 40 determines whether the value of the aberration error signal has reached the focus jump start threshold voltage (threshold). If the value of the aberration error signal has reached the threshold (YES in step S404), the process proceeds to step S405. On the other hand, if the value of the aberration error signal has not reached the threshold value (NO in step S404), the flow of step S404 is performed again.

  Also in step S412, the calculation unit 402 in the servo controller 40 determines whether the value of the aberration error signal has reached the focus jump start threshold voltage (threshold). If the value of the aberration error signal has reached the threshold (YES in step S412), the process proceeds to step S405. On the other hand, if the value of the aberration error signal has not reached the threshold value (NO in step S412), the flow of step S412 is performed again.

  In step S405, a focus jump is performed to the target recording layer.

  In step S406, the servo DSP 16 confirms whether the focus jump has been completed. If the focus jump has ended (YES in step S406), the process proceeds to step S407. On the other hand, if the focus jump has not ended (NO in step S406), the flow of step S406 is performed again.

  In step S407, it is confirmed by the servo DSP 16 whether the CL 26 has finished driving for the number of pulses (designated pulses) corresponding to the distance from L0 to L1. If the driving of the designated pulse has been completed (YES in step S407), the process proceeds to step S408. On the other hand, when the driving of the designated pulse has not ended (NO in step S407), the flow of step S407 is performed again.

  In step S408, the aberration servo is turned on, and the process proceeds to step S409.

  In step S409, the servo DSP 16 checks whether the value of the aberration error signal has reached 0 (the aberration error has crossed zero). If the value of the aberration error signal has reached 0 (YES in step S409), the process proceeds to step S410. On the other hand, if the value of the aberration error signal has not reached 0 (NO in step S409), the flow of step S409 is performed again.

  In step S410, the tracking servo and the sled servo are turned on. Then, the interlayer jump in the optical disc recording / reproducing apparatus 30 ends.

  According to the above configuration, the driving distance of the CL 26 can be adjusted by the number of pulses. Therefore, by driving the CL 26 in advance to a position where the aberration roughly matches after the focus jump, the aberration servo after the focus jump is achieved. It is possible to reduce the time required for the process.

  Next, FIG. 26 shows an operation flow in the optical disc recording / reproducing apparatus 30 when the CL 26 is driven without setting the driving distance in advance during the interlayer jump.

  First, the interlayer movement in the optical disc recording / reproducing apparatus 30 is started. When the interlayer jump starts, in step S421, the thread servo, tracking servo, and aberration servo are turned off.

  Subsequently, in step S422, it is determined whether the focus jump is performed from the L0 layer to the L1 layer or from the L1 layer to the L0 layer by the servo DSP 16. When it is determined that the focus jump is to be performed from the L0 layer toward the L1 layer (L0 → L1 in step S422), the process proceeds to step S423, and driving of the CL 26 to the OL2 side is started. Then, the process proceeds to step S424.

  If it is determined that the focus jump is to be performed from the L1 layer to the L0 layer (L1 → L0 in step S422), the process proceeds to step S431, and driving of the CL26 to the LD4 side is started. Then, the process proceeds to step S432.

  Subsequently, in step S424, the arithmetic unit 402 in the servo controller 40 determines whether the value of the aberration error signal has reached the focus jump start threshold voltage (threshold). If the value of the aberration error signal has reached the threshold value (YES in step S424), the process proceeds to step S425. On the other hand, if the value of the aberration error signal has not reached the threshold value (NO in step S424), the flow of step S424 is performed again.

  Also in step S432, the calculation unit 402 in the servo controller 40 determines whether the value of the aberration error signal has reached the focus jump start threshold voltage (threshold). If the value of the aberration error signal has reached the threshold value (YES in step S432), the process proceeds to step S425. On the other hand, when the value of the aberration error signal has not reached the threshold value (NO in step S432), the flow of step S432 is performed again.

  In step S425, the driving of CL26 is stopped. In step S426, a focus jump is performed to the target recording layer.

  In step S427, the servo DSP 16 confirms whether the focus jump has been completed. If the focus jump has ended (YES in step S427), the process proceeds to step S428. On the other hand, if the focus jump has not ended (NO in step S427), the flow of step S427 is performed again.

  In step S428, the aberration servo is turned ON, and the process proceeds to step S429.

  In step S429, the servo DSP 16 checks whether the value of the aberration error signal has reached 0 (the aberration error has crossed zero). If the value of the aberration error signal has reached 0 (YES in step S429), the process proceeds to step S430. On the other hand, if the value of the aberration error signal has not reached 0 (NO in step S429), the flow in step S429 is performed again.

  In step S430, the tracking servo and the sled servo are turned on. Then, the interlayer jump in the optical disc recording / reproducing apparatus 30 ends.

  According to the above configuration, it is possible to use, for the optical disc recording / reproducing apparatus 30, driving means that does not detect the position by the number of pulses, such as a DC motor.

  In addition, this invention is not limited to said embodiment, A various change is possible within the scope of the present invention. For example, in the above-described embodiment, after the aberration servo is turned on, it is configured to check whether the value of the aberration error signal has reached 0. However, the present invention is not particularly limited to this. For example, even if the aberration error signal does not reach 0, it may be configured to check whether the value of the aberration error signal has reached an allowable error range in which tracking servo and thread servo can be pulled.

  In this embodiment, the focus jump is performed after driving of the CL 26 is stopped, and the aberration servo is turned on after the focus jump is finished. However, the present invention is not limited to this, and the focus jump is finished. It is also possible to stop driving the CL 26 later and turn on the aberration servo.

  In this embodiment, the focus jump is performed after the aberration servo is turned off and the aberration servo is turned on after the focus jump is finished. However, the present invention is not limited to this, and the aberration servo is turned on. It is also possible to perform a focus jump while keeping

  In this embodiment, the threshold value for starting the focus jump is the voltage corresponding to the aberration error signal when it is located at the midpoint between L0 and L1, but other values can also be used. . This point will be described with reference to FIGS.

  FIG. 27 is a graph showing the relationship between the position of the CL 26 and the gain of the focus servo. In the drawing, the solid line is a graph when the L0 layer is in focus, and the broken line is a graph when the L1 layer is in focus. The horizontal axis indicates the position of CL26 by the number of pulses from the reference position. The vertical axis indicates the ratio of the gain of the focus servo at a certain position of the CL 26 to the focus servo gain at the CL optimum position in decibels (dB). Here, the CL optimum position means the position of the CL 26 that can optimally correct the spherical aberration. The optimum CL position varies depending on the recording layer. In the example shown in the drawing, the CL optimum position is about 50 pulses for the L0 layer and about 120 pulses for the L1 layer.

  As shown in FIG. 27, the focus servo gain increases as it approaches the CL optimum position corresponding to the recording layer that is in focus, and the focus servo gain decreases as the distance from the CL optimum position increases. Understandable. Therefore, when the CL 26 is moved from the optimum CL position of one recording layer to the optimum CL position of the other recording layer in the focus jump, the gain of the focus servo when the one recording layer is in focus is reduced. The gain of the focus servo increases when the other recording layer is in focus.

  Therefore, when the focus servo gain when the other recording layer is in focus reaches a range where focus servo control is possible, if the focus servo is controlled by performing a focus jump, the other recording layer The focus can be drawn accurately. Further, when the focus servo gain when one recording layer is in focus reaches a range in which the focus servo cannot be controlled, the focus is removed from one recording layer.

  For example, in FIG. 27, it is assumed that focus pull-in is possible when the ratio of the focus servo gain at a certain position of CL26 to the focus servo gain at the CL optimum position is about −10 dB or more. In this case, the focus jump from the L0 layer to the L1 layer may be performed when the number of pulses at the CL position reaches about 65. The focus jump from the L1 layer to the L0 layer may be performed when the number of pulses at the CL position reaches about 105. In either condition, the focus jump can be performed before the number of pulses at the CL position reaches the number of pulses at the intermediate point (about 85).

  Furthermore, when focusing on the L0 layer, it is desirable to limit the position of the CL 26 so that the number of pulses at the CL position is in the range of about 5 to about 95. When focusing on the L1 layer, it is desirable to limit the position of the CL 26 to a range where the number of pulses at the CL position is about 72 to about 170.

  FIG. 28 is a graph showing the relationship between the position of the CL 26 and the aberration error signal. In the drawing, the solid line is a graph when the L0 layer is in focus, and the broken line is a graph when the L1 layer is in focus. The horizontal axis indicates the position of CL26 by the number of pulses from the reference position. The vertical axis indicates the aberration error signal in voltage (V).

  Referring to FIGS. 27 and 28, when focusing on the L0 layer, the number of pulses at the CL optimum position is about 50, which corresponds to the case where the aberration error signal is about 0.03V. Therefore, when focusing on the L0 layer, the target voltage of the aberration error signal in the aberration servo is about 0.03V. On the other hand, when focusing on the L1 layer, the number of pulses at the CL optimum position is about 120, which corresponds to the case where the aberration error signal is about 0.08V. Therefore, when focusing on the L1 layer, the target voltage of the aberration error signal in the aberration servo is about 0.08V.

  Further, as described above, the focus jump from the L0 layer to the L1 layer may be performed when the number of pulses at the CL position reaches about 72. This is when the aberration error signal is about −0.12V. Corresponding to Therefore, the threshold value for starting the focus jump from the L0 layer to the L1 layer is about −0.12V. On the other hand, the focus jump from the L1 layer to the L0 layer may be performed when the number of pulses at the CL position reaches about 95, which corresponds to the case where the aberration error signal is about 0.24V. Therefore, the threshold value for starting the focus jump from the L1 layer to the L0 layer is about 0.24V.

  In the example shown in FIG. 23, the focus jump is performed with the value of the aberration error signal at the intermediate point between the CL optimum position for the L0 layer and the CL optimum position for the L1 layer as the threshold value. Therefore, in the example shown in FIG. 23, the focus jump is performed at the position where the number of pulses in the case of FIG. In the case of FIG. 27, since the focus servo can be pulled in when the number of pulses is in a range between about 65 and 105, in the focus jump of FIG. 23 where the number of pulses is about 80, The focus servo can be pulled in.

  Further, the number of pulses of about 85 at a time point between the CL optimum position for the L0 layer and the CL optimum position for the L1 layer, the gain ratio for the L0 layer that can perform focus jump more stably, and the L1 layer Since the number of pulses at the point where the gain ratio is equal (intermediate point) is approximately 80, it is an aberration at a point in time between the CL optimum position for the L0 layer and the CL optimum position for the L1 layer. The value of the error signal may be set as the above threshold value at which the focus jump can be performed more stably.

  As shown in FIG. 27, when a focus jump from the L0 layer to the L1 layer is performed, about 55 pulses are required rather than CL26 reaching the optimal CL position for the L1 layer, which is also a position where aberration correction for the L1 layer is completed. The focus servo can be pulled in from the previous time.

  In the present invention, the threshold value includes a time point approximately 55 pulses before the CL 26 reaches the optimal CL position for the L1 layer. Therefore, according to the present invention, a time point approximately 55 pulses before the correction is completed. It is actually possible to perform a focus jump with. In other words, it is actually possible to perform the focus jump at a time point approximately 55 pulses before the conventional case where the focus jump is performed after the correction is completed.

[Embodiment 6]
Still another embodiment of the present invention will be described with reference to FIG. The configurations other than those described in the present embodiment are the same as those of the optical disc recording / reproducing apparatus common to the above-described embodiments or the above-described embodiments. For convenience of explanation, members having the same functions as those shown in the drawings used in the description of the configuration of the optical disc recording / playback apparatus common to the embodiments are denoted by the same reference numerals. The description is omitted.

  FIG. 29 is a functional block diagram of the servo controller 40. First, the configuration of the servo controller 40 will be described. The servo controller 40 includes a storage unit 401, a calculation unit 412, and a total signal acquisition unit 413 as shown in FIG.

  The calculation unit 412 refers to the aberration error signal transmitted from the error signal generation circuit 41, the threshold information stored in the storage unit 401, and the total signal transmitted from the total signal acquisition unit 413, and performs predetermined processing. The calculation is performed according to the procedure. Then, switching is instructed to SW1 according to the result of the calculation.

  The total signal acquisition unit 413 acquires a total signal indicating the total amount of reflected light from the optical disc 1 from the signal processing circuit 17 and transmits it to the calculation unit 412.

  Next, processing in the calculation unit 412 when recording / reproducing is performed by the optical disc recording / reproducing apparatus 30 while switching between the two optical discs 1 will be described. Further, it is assumed that recording / reproduction of a plurality of recording layers is performed in the order of the first optical disc 1 and the second optical disc 1, respectively.

  When recording / reproducing the first optical disc 1, the calculation unit 412 corrects the value of the aberration error signal according to the total signal of the first optical disc 1 acquired by the total signal acquisition unit 413. Then, the corrected aberration error signal is compared with the threshold value. Subsequently, when the value of the corrected aberration error signal reaches the threshold value, the focus servo various compensation circuit 42 is instructed to drive the actuator driver 13 to perform the focus jump. As a result, a focus jump is performed.

  Further, when the value of the corrected aberration error signal does not reach the threshold value, the focus servo various compensation circuits 42 are instructed not to drive the actuator driver 13 to perform the focus jump.

  When recording / reproduction of the second optical disc 1 is performed following recording / reproduction of the first optical disc 1, the arithmetic unit 412 generates an aberration error signal according to the total signal of the second optical disc 1 acquired by the total signal acquisition unit 413. Correct the value. Then, the corrected aberration error signal is compared with the threshold value. Subsequently, when the value of the corrected aberration error signal reaches the threshold value, the focus servo various compensation circuit 42 is instructed to drive the actuator driver 13 to perform the focus jump. As a result, a focus jump is performed.

  Further, when the value of the corrected aberration error signal does not reach the threshold value, the focus servo various compensation circuits 42 are instructed not to drive the actuator driver 13 to perform the focus jump. In this way, each time the optical disk 1 to be recorded and reproduced is switched, the aberration error signal is corrected based on the total signal acquired by the total signal acquisition unit 413.

  As described above, the value of the aberration error signal is proportional to the signal from the reflected light of the optical disk, that is, the value of the total signal. Therefore, each time the optical disk 1 to be recorded / reproduced is switched, the aberration error signal is corrected based on the total signal acquired by the total signal acquisition unit 413, thereby correcting the aberration error signal corresponding to each of the two optical disks 1. It becomes possible. And the aberration error signal for every two optical disks 1 becomes uniform. Therefore, the servo DSP 16 can control the actuator driver 13 at a timing corresponding to each of the two optical disks 1.

  The storage unit 401, the calculation unit 412 and the total signal acquisition unit 413 are functional blocks realized by the CPU executing a program stored in the storage device and controlling peripheral circuits such as an input / output circuit (not shown). .

  In the present embodiment, the threshold information is stored in the storage unit 401. However, the threshold information is not necessarily limited thereto. For example, the threshold information is incorporated into a program executed by the calculation unit 412. It is also possible to adopt a configuration that does not store in 401.

  Further, in the present embodiment, the aberration error signal is corrected by the calculation unit 412 based on the total signal acquired by the total signal acquisition unit 413. However, the present invention is not necessarily limited to this. For example, the total signal acquisition unit The calculation unit 412 may correct the threshold value based on the total signal acquired in 413. The same applies when switching between three or more optical disks 1.

[Embodiment 7]
Next, still another embodiment of the present invention will be described with reference to FIGS. The servo DSP 16 of the optical disc recording / reproducing apparatus 30 of this embodiment does not always operate the spherical aberration servo, but stops the spherical aberration servo when the value of the aberration error signal is within a predetermined range. In addition, the same code | symbol is attached | subjected to the structure which has the function similar to the structure demonstrated in the said embodiment, and the description is abbreviate | omitted.

  FIG. 30 shows a schematic configuration of the servo controller 40 in the servo DSP 16. As illustrated, the servo controller 40 includes an aberration error signal acquisition unit 500, a range determination unit 501, and an aberration correction control unit 502.

  The aberration error signal acquisition unit 500 acquires an aberration error signal from the error signal generation circuit 41. The aberration error signal acquisition unit 500 transmits the acquired aberration error signal to the range determination unit 501 and the aberration correction control unit 502.

  The range determination unit 501 determines whether the value of the aberration error signal from the aberration error signal acquisition unit 500 is within a predetermined range. The range determination unit 501 notifies the aberration correction control unit 502 of the determination result. Details of the range determination unit 501 will be described later.

  The aberration correction control unit 502 instructs the various aberration servo compensation circuits 44 to perform appropriate aberration correction based on the aberration error signal from the aberration error signal acquisition unit 500 and the determination result from the range determination unit 501. . Specifically, when the value of the aberration error signal is outside a predetermined range, the aberration correction control unit 502 transmits an instruction based on the aberration error signal to the various aberration servo compensation circuits 44 to drive the aberration correction servo mechanism. To do. On the other hand, when the value of the aberration error signal is within the predetermined range, the aberration correction control unit 502 stops transmitting the instruction to the various aberration servo compensation circuits 44 in order to stop the driving.

  As a result, the aberration correction servo mechanism is not always driven, but is stopped when the value of the aberration error signal is within a predetermined range, so that power consumption due to the driving can be suppressed. Further, by stopping the driving, vibrations and heat generation of the stepping motor 33 which is a driving means of the aberration correction servo mechanism can be suppressed, so that the influence of the vibrations and heat generation on other components can be suppressed, and the optical pickup 7 can be suppressed. Can be maintained in a good state.

  Note that the predetermined range used for the determination by the range determination unit 501 is preferably a range in which the influence on various signals from the photodetector 6 is low even if the state of the spherical aberration changes slightly. This range will be described with reference to FIG.

  FIG. 31 shows an aberration error signal when the collimating lens 26 is moved from the home position to the end position with the focus position adjusted to the L0 layer with respect to the optical disc 1 having one recording layer (L0 layer). It shows a change. As shown in the figure, the aberration error signal is an S-shaped curve, and the intersection with the horizontal axis is the zero cross level. In the case of this zero cross level, the spherical aberration is optimally corrected.

  By the way, the spherical aberration is mainly caused by the thickness from the surface of the optical disc 1 to the recording layer. Therefore, in FIG. 31, the position of the collimating lens 26 is shown on the horizontal axis in association with the thickness error from the position where the spherical aberration is optimally corrected.

  Further, the thickness is different in each part of the optical disc 1. Therefore, when there is no focus jump or other disturbance factor, the aberration error signal has a waveform that vibrates with the rotation period of the optical disc 1.

  For this reason, even if the value of the aberration error signal deviates from the zero cross level, there is a high possibility of returning to the zero cross level. Therefore, assuming that the range of vibration centered on the zero cross level is the optimum range, when the value of the aberration error signal is included in this optimum range, the aberration error can be obtained without moving the collimating lens 26 based on the aberration error signal. The signal value is likely to return to the zero cross level. Therefore, it can be understood that it is desirable to include the optimum range in the predetermined range.

  Similarly, even if the value of the aberration error signal deviates from the optimum range, there is a high possibility that it will return to the optimum range again. Therefore, if an allowable range is a range including the optimal range, a range in which the lower limit of the optimal range is the upper limit of the vibration, and a range in which the upper limit of the optimal range is the lower limit of the vibration, the aberration error signal is included in the allowable range. If the value is included, the value of the aberration error signal is likely to return to the optimum range without moving the collimating lens 26 based on the aberration error signal. Therefore, it can be understood that the predetermined range may include a case that is out of the optimal range but still within the allowable range.

  Next, details of the range determination unit 501 will be described. As illustrated in FIG. 30, the range determination unit 501 includes an optimum range determination unit 503, an allowable range determination unit 504, and a determination result generation unit 505.

  The optimal range determination unit 503 determines whether the value of the aberration error signal from the aberration error signal acquisition unit 500 is within the optimal range. The optimum range determination unit 503 notifies the determination result generation unit 505 of the determination result.

  The allowable range determination unit 504 determines whether the value of the aberration error signal from the aberration error signal acquisition unit 500 is within the allowable range. The allowable range determination unit 504 notifies the determination result generation unit 505 of the determination result.

  The determination result generation unit 505 generates an aberration determination signal as a determination result based on the determination result from the optimum range determination unit 503 and the determination result from the allowable range determination unit 504. The determination result generation unit 505 transmits the generated aberration determination signal to the aberration correction control unit 502.

  Here, the aberration determination signal is a binary signal that can be at the H (high) level and the L (low) level, as shown in FIG. The aberration determination signal is at the H level when the value of the aberration error signal is within the optimum range or deviates from the optimum range, but is still within the allowable range, and at the L level otherwise. Is.

  According to the above configuration, when the value of the aberration error signal is within the optimum range or deviates from the optimum range, but is still within the allowable range, the determination result generation unit 505 determines the aberration determination at the H level. The signal is transmitted to the aberration correction control unit 502. When the aberration correction control unit 502 receives the H level aberration determination signal, the aberration correction control unit 502 stops the instruction to the various aberration servo compensation circuits 44 in order to stop driving the aberration correction servo mechanism.

  In addition, when the value of the aberration error signal is not yet within the optimum range, or the aberration error signal is out of the allowable range due to an impact or other disturbance factor, the determination result generation unit 505 determines the aberration determination at the L level. The signal is transmitted to the aberration correction control unit 502. When the aberration correction control unit 502 receives the L-level aberration determination signal, the aberration correction control unit 502 instructs the aberration servo compensation circuit 44 to drive the aberration correction servo mechanism.

  As a result, the aberration correction servo mechanism is not always driven, but is stopped when the value of the aberration error signal is within a predetermined range, so that power consumption due to the driving can be suppressed. Furthermore, even if the drive of the aberration correction servo mechanism is stopped, the influence on various signals from the photodetector 6 can be suppressed.

  Next, the flow of processing during an aberration servo operation including the servo controller 40 having the above configuration will be described with reference to the flowchart shown in FIG. 32 using FIGS. 30 and 3.

  First, various initial settings are made (S500). At this time, the aberration determination signal may be either H level or L level, but in the case of FIG. 32, it is set to H level.

  Next, the determination result generation unit 505 determines whether or not the current aberration determination signal is at the H level (S501). If it is at the L level (NO in S501), the process proceeds to S502. On the other hand, if it is at the H level (YES in S501), the process proceeds to S504.

  In S502, the optimal range determination unit 503 determines whether or not the spherical aberration error signal is within the optimal range. If it is out of the optimum range (NO in S502), the following aberration correction servo processing (S506 to S508) is executed.

  That is, the aberration correction control unit 502 determines whether or not the aberration error signal from the aberration error signal acquisition unit 500 is zero or more (S506). If the aberration error signal is greater than or equal to zero (YES in S506), the aberration correction control unit 502 instructs the stepping motor control circuit 46 via the aberration servo various compensation circuit 44 to set the collimating lens 26 to 1 in the end position direction. Step movement is performed (S507). Thereafter, the process returns to step S501.

  On the other hand, if the aberration error signal is less than zero (negative) (NO in S506), the aberration correction control unit 502 instructs the stepping motor control circuit 46 via the aberration servo various compensation circuit 44 to move the collimating lens 26. Move one step in the home position direction (S508). Thereafter, the process returns to step S501.

  On the other hand, if the aberration error signal is within the optimum range in S502 (YES in S502), the determination result generation unit 505 sets the aberration determination signal to the H level and transmits it to the aberration correction control unit 502 ( S503). Accordingly, the aberration correction control unit 502 returns to S501 without performing the aberration correction servo processing (S506 to S508).

  On the other hand, in S504, the allowable range determination unit 504 determines whether or not the spherical aberration error signal is within the allowable range. If it is within the allowable range (YES in S504), the determination result generation unit 505 maintains the aberration determination signal at the H level and transmits it to the aberration correction control unit 502. Accordingly, the aberration correction control unit 502 returns to S501 without performing the aberration correction servo processing (S506 to S508).

  On the other hand, when the aberration error signal is out of the allowable range in S504 (NO in S504), the determination result generation unit 505 sets the aberration determination signal to L level and transmits it to the aberration correction control unit 502. (S505). Accordingly, the aberration correction control unit 502 executes the aberration correction servo processing (S506 to S508). Thereafter, the process returns to S501.

  As described above, in this embodiment, if the aberration determination signal is at the L level, the aberration correction servo mechanism is driven, whereas if the aberration determination signal is at the H level, the driving of the aberration correction servo mechanism is stopped. ing. Thereby, useless driving of the collimating lens driving motor 33 can be prevented.

  Specifically, the collimating lens driving motor 33 is not driven in accordance with the noise of the small aberration error signal or the fluctuation of the aberration error signal due to the rotation of the optical disc 1, and as a result, the collimating lens driving motor 33 is excessively driven. Overheating due to driving can be prevented.

  In addition, since the optical pickup 7 is provided with a high-temperature component such as the semiconductor laser 4, it is possible to satisfy the demand of suppressing the temperature of other components in order not to raise the temperature further.

  Further, by preventing unnecessary driving of the collimating lens driving motor 33, vibration generated when the collimating lens driving motor 33 is driven can be suppressed.

  In this embodiment, the spherical aberration is corrected by moving the collimating lens 26 in the optical axis direction by the collimating lens driving motor 33. Therefore, when driving the aberration correction servo mechanism is stopped, it is not necessary to apply a voltage to the collimating lens driving motor 33. As a result, power consumption in the collimating lens driving motor 33 can be suppressed.

  In the present embodiment, the optimum range and the allowable range include the zero cross level. However, if the target voltage of the aberration correction servo is different from the zero cross level, the zero range may not be included.

[Embodiment 8]
Next, still another embodiment of the present invention will be described with reference to FIGS. The servo DSP 16 of the optical disk recording / reproducing apparatus 30 of the present embodiment suppresses the influence on the correction of spherical aberration due to a defect or the like of the optical disk 1 or some sudden abnormality. In addition, the same code | symbol is attached | subjected to the structure which has the function similar to the structure demonstrated in the said embodiment, and the description is abbreviate | omitted.

  FIG. 33 shows a configuration relating to the focus servo and the spherical aberration servo in the optical disc recording / reproducing apparatus 30 of the present embodiment, and corresponds to FIG. The optical disk recording / reproducing apparatus 30 of the present embodiment shown in FIG. 33 has an LPF (low-pass filter, LPF) between the error signal generation circuit 41 and the various aberration servo compensation circuits 44, as compared with the configuration shown in FIG. Low-pass filter) 700 is inserted, and other configurations are the same.

  FIG. 34 shows temporal changes of various signals when the light beam passes through the black dots BD of the optical disc 1 in the optical disc recording / reproducing apparatus 30 shown in FIG. FIG. 35 is a comparative example of FIG. 34, and shows temporal changes of various signals when the light beam passes through the black dots BD of the optical disc 1 in the optical disc recording / reproducing apparatus shown in FIG.

  Regarding the graphs shown in FIGS. 34 and 35, the signals are a total signal, an aberration error signal, and an RF signal in order from the top. The horizontal axis is an axis indicating time, and the vertical axis is an axis indicating voltage. One scale on the horizontal axis is 200 μs, and one scale on the vertical axis depends on the signal. Furthermore, the time axis (horizontal axis) passes from the right side to the left side. That is, the right side is old and the left side is new. Further, the period surrounded by the alternate long and short dash line is a period during which the light beam passes through the black dots BD.

  Referring to FIG. 35, it can be understood that in the conventional optical disc recording / reproducing apparatus, when the light beam passes through the black dot BD, the total signal, the aberration error signal, and the RF signal all fluctuate. In particular, when the aberration error signal fluctuates, the spherical aberration deviates from an appropriate correction position. Further, it takes time to return to an appropriate correction position thereafter.

  On the other hand, referring to FIG. 34, in the optical disc recording / reproducing apparatus 30 of this embodiment, it can be understood that the fluctuation of the aberration error signal does not occur even when the light beam passes through the black dot BD. Thereby, it can prevent that the collimating lens 26 remove | deviates from the appropriate correction position of spherical aberration, and it can avoid spending time until it returns to an appropriate correction position after that.

  Note that the LPF 700 is preferably one that blocks a frequency component generated in the aberration error signal when it is abnormal.

  For example, an abnormality caused by a defect or the like of the optical disk 1 may occur every time the optical disk 1 makes one round. Therefore, the LPF 700 may block a signal having a frequency higher than the rotational speed of the optical disc 1. In this case, the influence on the correction of the spherical aberration can be suppressed with respect to the abnormality due to the defect of the optical disk.

  Also, for example, Blu-ray Disc, which is one standard for next-generation optical disc technology, allows a defect in the optical disc 1 corresponding to 20 μs. Therefore, the LPF 700 may block a signal having a frequency higher than 50 kHz. In this case, it is possible to suppress the influence on the correction of the spherical aberration with respect to the abnormality due to the defect on the optical disc 1 which is not allowed.

  When using the stepping motor 33 that changes the collimating lens 26 stepwise, the LPF 700 blocks a signal having a frequency higher than the number of pulses that the stepping motor control circuit 46 can input to the stepping motor 33 per second. Also good. For example, when using the stepping motor 33 that requires 1 ms to move by one step, a signal having a frequency higher than 1 kHz may be cut off.

  Usually, the stepping motor control circuit 46 is set to control the stepping motor 33 to change the collimating lens 26 at a change rate (number of pulses that can be changed per second) that can correct spherical aberration. That is, it can be said that the frequency component higher than the change rate in the aberration error signal is a component unrelated to the correction of spherical aberration for the stepping motor control circuit 46. Therefore, even if the LPF 700 cuts off a signal having a frequency higher than the above change rate, it hardly affects the correction of the spherical aberration.

[Embodiment 9]
Next, still another embodiment of the present invention will be described with reference to FIG. The servo DSP 16 of the optical disk recording / reproducing apparatus 30 of the present embodiment suppresses the influence on the correction of spherical aberration due to a defect or the like of the optical disk 1 or some sudden abnormality. In addition, the same code | symbol is attached | subjected to the structure which has the function similar to the structure demonstrated in the said embodiment, and the description is abbreviate | omitted.

  FIG. 36 shows a schematic configuration of the servo controller 40 in the servo DSP 16 of the optical disc recording / reproducing apparatus 30 of the present embodiment. As illustrated, the servo controller 40 includes an aberration error signal acquisition unit 710, an abnormality detection unit 711, and an aberration correction control unit 712.

  The aberration error signal acquisition unit 710 acquires an aberration error signal from the error signal generation circuit 41. The aberration error signal acquisition unit 710 transmits the acquired aberration error signal to the abnormality detection unit 711.

  The abnormality detection unit 711 detects whether or not the signal is abnormal based on the aberration error signal from the aberration error signal acquisition unit 710. The abnormality of the signal can be detected, for example, by detecting an aberration error signal exceeding a preset threshold value or detecting an aberration error signal that fluctuates rapidly in a short time. When detecting an abnormality, the abnormality detection unit 711 notifies the aberration correction control unit 712 to that effect.

  The aberration correction control unit 712 controls the correction of spherical aberration by instructing the various aberration servo compensation circuit 44, the jump control circuit 45, the stepping motor control circuit 46, the switch SW3, and the switch SW4. In the present embodiment, the aberration correction control unit 712 turns off the switch SW3 when notified from the abnormality detection unit 711 that an abnormality has been detected. Thereby, since the driving of the stepping motor 33 is stopped, the collimating lens 26 can be prevented from deviating from an appropriate correction position of the spherical aberration as described above.

  The aberration correction controller 712 may instruct the aberration servo compensation circuit 44 to stop the instruction to the stepping motor control circuit 46 instead of turning off the switch SW3, The stepping motor control circuit 46 may be instructed to stop the pulse input.

[Embodiment 10]
Still another embodiment of the present invention will be described below with reference to FIGS. The servo DSP 16 of the optical disc recording / reproducing apparatus 30 of the present embodiment corrects spherical aberration in a state corresponding to the next recording layer when the focus crosses a certain recording layer in the optical disc 1 having a plurality of recording layers. Is. In addition, the same code | symbol is attached | subjected to the structure which has the function similar to the structure demonstrated in the said embodiment, and the description is abbreviate | omitted.

  FIG. 37 is a schematic diagram showing the configuration of the servo controller 40 of the servo DSP 16 in the optical disc recording / reproducing apparatus 30 of the present embodiment. As shown in FIG. 37, the servo controller 40 includes a comparison unit 901, a measurement unit 902, an aberration correction value switching unit 903, a circuit control unit 904, and a control unit 905.

  The comparison unit 901 receives the focus error signal from the error signal generation circuit 41 and compares the level of the focus error signal with the level of the layer detection threshold. When the comparison unit 901 determines that the level of the focus error signal has reached the level of the layer detection threshold, the comparison unit 901 outputs a peak detection signal indicating that to the measurement unit 902 and the aberration correction value switching unit 903.

  When the measurement unit 902 receives the peak detection signal from the comparison unit 901, the measurement unit 902 adds 1 to a counter (not shown) included in the measurement unit 901, the number recorded in the memory (not shown) included in the measurement unit 902, and the number indicated by the counter Are compared. When the number recorded in the memory matches the number indicated by the counter, the measuring unit 902 outputs matching information indicating that to the focus servo various compensation circuits 903 and the circuit control unit 904.

  That is, the measurement unit 902 counts the number of peaks of the focus error signal detected by the comparison unit 901, and outputs information indicating that a predetermined number of peaks have been detected.

  When the aberration correction value switching unit 903 receives the peak detection signal from the comparison unit 901, the spherical aberration is optimized so as to be optimal for the information recording layer next to the information recording layer that is the target of spherical aberration correction at that time. The aberration correction value switching command is output to the aberration servo compensation circuit 904 so as to switch the correction value. In addition, the aberration correction value switching unit 903 outputs an aberration correction value switching command, and simultaneously outputs aberration correction value switching information to the circuit control unit 904.

  The next information recording layer is the next information recording layer in the moving direction of the objective lens. For example, when the objective lens moves in the direction from the first information recording layer to the third information recording layer, the information recording layer next to the first information recording layer is the second information recording layer.

  The circuit control unit 904 includes switches SW1 and SW2 for turning on the focus servo based on the coincidence information output from the measurement unit 902 and the aberration correction value switching information output from the aberration correction value switching unit 903, and The switches SW3 and SW4 for turning on the aberration servo are switched.

  The control unit 905 controls each unit of the servo controller 40 based on a command from the system controller 18.

  When the coincidence information is received from the measurement unit 902, the focus servo various compensation circuit 42 pulls the focus into the information recording layer in which the peak is generated. At this time, the focus servo various compensation circuit 42 calculates a correction value for focus servo based on the focus error signal output from the error signal generation circuit 41. The various focus servo compensation circuits 42 output the calculated correction values for focus servo to the focus driver 51.

  When each aberration servo compensation circuit 44 receives an aberration correction value switching command from the aberration correction value switching unit 903, the spherical aberration is optimized so as to be optimal for the next information recording layer based on the aberration correction value switching command. The correction value is calculated. At this time, the various aberration servo compensation circuit 44 calculates a correction value for the aberration servo based on the aberration error signal output from the error signal generation circuit 41. The various aberration servo compensation circuits 44 output the calculated correction values to the stepping motor control circuit 46.

(Processing flow related to focus search)
The flow of processing when performing a focus search in the optical disc recording / reproducing apparatus 30 will be described with reference to FIG. FIG. 38 is a flowchart showing the flow of the focus pull-in process in the optical disc recording / reproducing apparatus 30.

  Hereinafter, by moving the objective lens 2 from the initial position of the objective lens 2 toward the optical disc 1 with respect to the optical disc 1 having the information recording layers from the first layer to the Nth layer, A flow of processing when performing a focus search from the information recording layer to the Nth information recording layer in order will be described.

  As shown in FIG. 38, first, the control unit 905 sets the value X indicated by the counter of the measurement unit 902 to 0 based on a command from the system controller 18 (S901), and stores N in the memory of the measurement unit 902. Record the value of.

  Then, the control unit 905 instructs the aberration correction value switching unit 903 to optimize the spherical aberration for the first information recording layer. The aberration correction value switching unit 903 controls the switches SW3 and SW4 to turn on the aberration servo via the circuit control unit 904, and the aberration servo various compensation circuit 44 has spherical aberration with respect to the first information recording layer. The correction value of the aberration servo that is optimal is calculated.

  The various aberration servo compensation circuits 44 output the calculated correction values to the stepping motor control circuit 46. Thereby, the collimating lens driving mechanism 27 is controlled via the driving collimating lens motor driver 25, and the position of the collimating lens 26 is adjusted (S902).

  Thereafter, the system controller 18 controls the actuator 3 to move the objective lens 2 from the initial position toward the optical disk (S903). At this time, the error signal generation circuit 41 generates a focus error signal from the light beam reflected by the optical disc 1 and outputs the focus error signal to the comparison unit 901.

  Upon receiving the focus error signal, the comparison unit 901 compares the level of the focus error signal with the level of the layer detection threshold (S904).

  When a focus error signal having a level equal to or higher than the layer detection threshold is detected (YES in S905), comparison unit 901 outputs a peak detection signal to measurement unit 902 and aberration correction value switching unit 903.

  When receiving the peak detection signal, the measuring unit 902 adds 1 to the value X indicated by the counter (S906).

  Here, the measurement unit 902 compares the value N recorded in the memory with the value X indicated by the counter (S907).

  If value X indicated by the counter is smaller than the value of N recorded in the memory (NO in S905), measurement unit 902 postpones the output of the coincidence information (returns to S902).

  When returning to S902, the aberration correction value switching unit 903 that has received the peak detection signal supplies the aberration servo various compensation circuit 44 so as to switch the correction value of the spherical aberration so as to be optimal for the (X + 1) th information recording layer. An aberration correction value switching command is output (S902). Thereafter, the processes of S903 to S907 are executed.

  On the other hand, when the value of N recorded in the memory matches the value indicated by the counter (YES in S905), measurement unit 902 outputs the matching information to focus servo various compensation circuits 42 and circuit control unit 904.

  When the coincidence information is received, the circuit control unit 904 controls the switches SW1 and SW2 to turn on the focus servo, and the focus servo various compensation circuit 42 pulls the focus into the Nth layer (S908). .

  When the focus pull-in to the Nth layer is finished, a series of processes related to the focus search is finished.

(Effect of optical disk recording / reproducing apparatus 30)
Next, effects of the optical disc recording / reproducing apparatus 30 will be described with reference to FIG. FIG. 39 is a diagram for explaining the effect of the optical disc recording / reproducing apparatus 30. In FIG. FIG. 6A shows a case where the objective lens is moved from the initial position in a direction approaching the optical disc in a state where the spherical aberration is optimally corrected for the third information recording layer in the conventional optical disc recording / reproducing apparatus. 2 shows the waveform of the focus error signal obtained. On the other hand, FIG. 5B shows a focus error signal obtained when the objective lens 2 is moved while sequentially switching the information recording layer to be corrected for spherical aberration in the optical disc recording / reproducing apparatus 30 of the present embodiment. A waveform is shown.

  As shown in FIG. 39A, when the objective lens is moved in the direction approaching the optical disc 1 from the initial position in a state where the spherical aberration is optimally corrected in the third information recording layer, The peak of the focus error signal related to the three information recording layers is a peak equal to or higher than the layer detection threshold having (+) polarity (extending in FIG. 39), but the focus error signal related to the first and second information recording layers. This peak is below the layer detection threshold.

  In this state, the first and second information recording layers are not recognized, and only the third information recording layer is recognized. Therefore, the optical disc recording / reproducing apparatus misrecognizes the third information recording layer as the first information recording layer, and further moves the objective lens. As a result, if the optical disk is composed of three information recording layers, the objective lens may collide with the optical disk.

  On the other hand, as shown in FIG. 39B, when the objective lens 2 is moved while sequentially switching the information recording layers to be corrected for spherical aberration, the peak of the focus error signal for each information recording layer is It becomes more than the layer detection threshold. Therefore, there is little possibility of erroneously recognizing the information recording layer, and the focus can be reliably pulled into the target information recording layer. Therefore, it is possible to reduce the possibility that the objective lens collides with the optical disc due to erroneous recognition of the information recording layer.

  In the above embodiment, the correction value for the aberration servo is calculated based on the aberration error signal generated by the error signal generation circuit 41. However, the correction value of the spherical aberration appropriate for each information recording layer is previously calculated. The aberration correction value switching unit 903 may be configured to switch the correction value based on the peak detection signal.

  In the above embodiment, the comparison unit 901 outputs the peak detection signal when the level of the focus error signal is equal to or higher than the layer detection threshold, but the level of the focus error signal is equal to or higher than the layer detection threshold. A peak detection signal may be output later when the value falls below the layer detection threshold.

  Further, when the level of the focus error signal is lower than the reference level of the focus error signal by a predetermined value or more, the comparison unit 901 may output a peak detection signal. That is, the comparison unit 901 may detect a peak of a focus error signal having a polarity of (−) (extending downward in FIG. 39).

  Further, in the above embodiment, when the peak detection signal is received, the aberration correction value switching unit 903 is optimized for the information recording layer next to the information recording layer that is the correction target of the spherical aberration at that time. An aberration correction value switching command is output to the various aberration servo compensation circuit 44 so as to switch the correction value of the spherical aberration. However, an intermediate point of the information recording layer may be set as a spherical aberration correction target.

  For example, in the case of a three-layer optical disc, the intermediate point between the first information recording layer and the second information recording layer and the intermediate point between the second information recording layer and the third information recording layer are set as spherical aberration correction targets. Also good. In this case, when the peak detection signal is received, the aberration correction value switching unit 903 sets a correction value suitable for the intermediate point ahead in the focal movement direction with respect to the intermediate point that is the target of spherical aberration correction at that time. Thus, an aberration correction value switching command may be output to the various aberration servo compensation circuits 44 as described above.

  Further, the correction value of the spherical aberration does not necessarily need to be optimal for each information recording layer, and is at least enough to obtain a focus error signal at a level equal to or higher than the layer detection threshold value from each information recording layer. That's fine.

[Embodiment 11]
Still another embodiment of the present invention will be described below with reference to FIGS. When performing a focus search on the optical disc 1 having two recording layers, the servo DSP 16 of the optical disc recording / reproducing apparatus 30 of the present embodiment corrects the spherical aberration corresponding to the midpoint between the two recording layers, and focuses Based on the value of the aberration error signal after drawing, the recording layer into which the focus is drawn is determined. In addition, the same code | symbol is attached | subjected to the structure which has the function similar to the structure demonstrated in the said embodiment, and the description is abbreviate | omitted.

  FIG. 40 is a schematic diagram showing the configuration of the servo controller 40. As shown in FIG. 40, the servo controller 40 includes a comparison unit 1001, a measurement unit 1002, a measurement unit 1003, a determination unit 1004, a control unit 1005, and a circuit control unit 1006.

  The comparison unit 1001 receives the focus error signal from the error signal generation circuit 41 and compares the level of the focus error signal with the level of the detection threshold. When the comparison unit 1001 determines that the level of the focus error signal has reached the detection threshold level, the comparison unit 1001 outputs a peak detection signal indicating that to the measurement unit 1002.

  When the measurement unit 1002 receives the peak detection signal from the comparison unit 1001, the measurement unit 1002 adds 1 to the counter (not shown) included in the measurement unit 1001, and the counter indicates the number recorded in the temporary storage memory (not shown) included in the measurement unit 1002. Compare numbers. When the number recorded in the temporary storage memory matches the number indicated by the counter, the measurement unit 1002 outputs matching information indicating that fact to the focus servo various compensation circuits 903 and the circuit control unit 1006.

  The measuring unit 1003 measures the voltage of the aberration error signal output from the error signal generation circuit 41. The measurement unit 1003 outputs the measurement result to the determination unit 1004.

  The determination unit 1004 determines whether the voltage value of the aberration error signal measured by the measurement unit 1003 is within a predetermined range. Specifically, the determination unit 1004 determines whether the voltage value of the aberration error signal is a positive value or a negative value.

  The determination unit 1004 determines that the target information recording layer is the L1 layer and the voltage value of the aberration error signal is a negative value, or the target information recording layer is the L0 layer, and the aberration error When the voltage value of the signal is a positive value, abnormal information indicating that the focus is drawn into the wrong information recording layer is output to the control unit 1005.

  The determination unit 1004 determines that the target information recording layer is the L1 layer and the voltage value of the aberration error signal is a positive value, or the target information recording layer is the L0 layer, and the aberration error When the voltage value of the signal is a negative value, normal information indicating that the focus has been drawn into the target information recording layer is output to the control unit 1005.

  The control unit 1005 controls each unit of the servo controller 40 based on a command from the system controller 18. In particular, when the control unit 1005 receives abnormality information from the determination unit 1004, the focus servo various compensation circuits 42 so as to perform a focus jump (interlayer jump) to an information recording layer different from the information recording layer on which the focus has been drawn. To instruct.

  The circuit control unit 1006 turns on the switches SW1 and SW2 for turning on the focus servo and the aberration servo on the basis of the coincidence information outputted from the measurement unit 1002 and the control signal outputted from the control unit 1005. Switches SW3 and SW4 for switching.

  In the present embodiment, the jump control circuit 45 corrects spherical aberration suitable for an intermediate point between the L0 layer and the L1 layer in the stacking direction, that is, a point (or layer) at an equal distance from the L0 layer and the L1 layer. By setting the value and outputting the correction value to the stepping motor control circuit 46, the position of the collimating lens is controlled.

(Significance of voltage measurement of aberration error signal)
Here, the significance of measuring the voltage of the aberration error signal will be described with reference to FIG. FIG. 41 is a graph showing a change in the voltage of the aberration error signal obtained when the collimator lens (CL) is moved from the home position to the end sensor position when the L0 layer or the L1 layer is in focus.

  As shown in the figure, when the collimating lens is arranged so that the spherical aberration is optimal at the intermediate point between the L0 layer and the L1 layer, the voltage value of the aberration error signal derived from each layer is the reference line 1010. It becomes the value of the intersection with the line of the aberration error signal originating from each layer. That is, when the L1 layer is in focus, the voltage value of the aberration error signal is a positive value (the value indicated by the arrow 1011), and when the L0 layer is in focus, the aberration error signal The voltage value is a negative value (value indicated by an arrow 1012).

  Therefore, by measuring whether the voltage value of the aberration error signal is a positive value or a negative value, it is possible to determine which information recording layer the focus has been drawn into. .

(Processing flow for focus pull-in)
Next, the flow of processing when the optical disc recording / reproducing apparatus 30 performs focus pull-in will be described with reference to FIG. FIG. 42 is a flowchart showing the flow of the focus pull-in process in the optical disc recording / reproducing apparatus 30.

  First, the control unit 1005 instructs the lamp circuit 43 to set the focus pull-in to the L0 layer or the L1 layer based on an instruction from the system controller.

  Then, as shown in FIG. 42, the control unit 1005 moves the collimating lens 26 to the home position by controlling the collimating lens driving mechanism 27 via the stepping motor control circuit 46 and the driving collimating lens motor driver 25 ( S1001).

  Then, the circuit control unit 1006 operates the switches SW3 and SW4 for turning on the aberration servo, and connects the jump control circuit 45 and the stepping motor control circuit 46. The jump control circuit 45 sets a spherical aberration correction value suitable for an intermediate point between the L0 layer and the L1 layer, and moves the collimating lens 26 based on this correction value (S1002).

  Thereafter, the control unit 1005 outputs “1” to the measurement unit 1002 when the focus is pulled into the L1 layer, and “2” when the focus is pulled into the L0 layer. The counter of the unit 1002 is set to 0.

  When receiving the signal from the control unit 1005, the measuring unit 1002 records “1” or “2” in the temporary storage memory provided in the measuring unit 1002.

  Further, the control unit 1005 outputs information indicating which of the L0 layer and the L1 layer is the target information recording layer to the determination unit 1004.

  Upon receiving the information, the determination unit 1004 records the information in a temporary storage memory (not shown) provided in itself.

  Thereafter, the control unit 1005 operates the switches SW1 and SW2 to connect the ramp circuit 43 and the actuator 3. The ramp circuit 43 moves the objective lens 2 from the initial position in a direction approaching the optical disc 1 by controlling the actuator 3. At this time, the error signal generation circuit 41 generates a focus error signal from the light beam reflected by the optical disc 1 and outputs the focus error signal to the comparison unit 1001.

  When the focus error signal is received, the comparison unit 1001 compares the level of the focus error signal with the level of the layer detection threshold as in the processes S904 to S908 of FIG. When a focus error signal having a level equal to or higher than the layer detection threshold is detected, the comparison unit 1001 outputs a peak detection signal to the measurement unit 1002.

  When receiving the peak detection signal, the measuring unit 1002 adds 1 to the value indicated by the counter. Here, the measurement unit 1002 compares the value recorded in the temporary storage memory with the value indicated by the counter.

  If the value indicated by the counter does not match the value recorded in the memory, the measuring unit 1002 postpones the output of the matching information and waits until a new peak detection signal is received.

  On the other hand, when the value recorded in the memory matches the value indicated by the counter, the measuring unit 1002 outputs the coincidence information to the focus servo various compensation circuits 42 and the circuit control unit 1006.

  When the coincidence information is received, the circuit control unit 1006 controls the switch SW2 to turn on the focus servo, and the focus servo various compensation circuit 42 pulls in the focus (S1004).

  When the focus pull-in is completed (YES in S1004), measurement unit 1003 measures the voltage of the aberration error signal output from error signal generation circuit 41. The measurement unit 1003 outputs the measurement result to the determination unit 1004.

  Upon receiving the measurement result, the determination unit 1004 determines whether the voltage value of the aberration error signal is a positive value or a negative value.

  Further, the determination unit 1004 determines that the target information recording layer is the L0 layer (YES in S1005), and the voltage value of the aberration error signal is a positive value (NO in S1006). When the information recording layer is the L1 layer (NO in S1005) and the voltage value of the aberration error signal is a negative value (NO in S1008), abnormality information is output to the control unit 1005.

  When the abnormal information is received, the control unit 1005 instructs the focus servo compensation circuit 42 to perform a focus jump to an information recording layer different from the information recording layer on which the focus has been drawn (S1007 or S1009).

  On the other hand, the determination unit 1004 determines that the target information recording layer is the L0 layer (YES in S1005), and the voltage value of the aberration error signal is a negative value (YES in S1006). When the information recording layer to be performed is the L1 layer (NO in S1005) and the value of the voltage of the aberration error signal is a positive value (YES in S1008), normal information is output to the control unit 1005.

  Upon receiving normal information, the control unit 1005 ends a series of focus pull-in processes.

  When performing the focus jump, the objective lens 2 is moved so that the target information recording layer is in focus. At this time, it is desirable to turn on the aberration servo.

(Effect of optical disk recording / reproducing apparatus 30)
As described above, the optical disc recording / reproducing apparatus 30 measures the voltage of the aberration error signal derived from the information recording layer on which the focus is drawn, so that the information recording layer on which the focus is drawn has the target information. It is determined whether or not it is a recording layer.

  Therefore, it is possible to determine whether or not the information recording layer on which the focus is drawn is the target information recording layer without reading the data recorded on the information recording layer on which the focus is drawn. .

  Therefore, it is possible to shorten the processing time when data is recorded or reproduced on the target information recording layer.

  In the above embodiment, the determination unit 1004 determines whether the voltage value of the aberration error signal is a positive value or a negative value. It may be determined whether or not the voltage value of is greater than or equal to a positive threshold value or less than or equal to a negative threshold value.

  The correction value of the spherical aberration is not necessarily optimum for the intermediate point between the L1 layer and the L0 layer, and a focus error signal having a level equal to or higher than the detection threshold can be obtained from at least the L1 layer and the L0 layer. Anything is acceptable.

  In the above embodiment, the optical disc 1 has two information recording layers. However, the optical disc 1 may have three information recording layers (L2, L1, L0). In that case, spherical aberration correction suitable for the intermediate point between the L2 layer and the L1 layer or the intermediate point between the L1 layer and the L0 layer is performed, and the difference between the voltage of the aberration error signal and the reference level is calculated. What is necessary is just to determine whether this difference is in the predetermined range.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

  For example, in the above embodiment, the stepping motor 33 is used to drive the collimating lens 26, but a motor provided with a rotary encoder may be used. In this case, the count value may be obtained from the rotary encoder.

  In the above embodiment, the spherical aberration is corrected by driving the collimating lens 26 in the optical axis direction. However, by adding a beam expander and driving the beam expander in the optical axis direction. You can go. Alternatively, a liquid crystal element may be added and a voltage may be applied to the liquid crystal element. Alternatively, a solid immersion lens may be added between the objective lens and the optical disk, and the solid immersion lens may be driven in the optical axis direction.

  Finally, each block of the servo DSP 16 may be configured by hardware logic, or may be realized by software using a CPU as follows.

  That is, the servo DSP 16 includes a CPU (central processing unit) that executes instructions of a control program that realizes each function, a ROM (read only memory) that stores the program, a RAM (random access memory) that expands the program, A storage device (recording medium) such as a memory for storing the program and various data is provided. An object of the present invention is to provide a recording medium in which a program code (execution format program, intermediate code program, source program) of a control program of the servo DSP 16 which is software for realizing the above-described functions is recorded so as to be readable by a computer. This can also be achieved by supplying the servo DSP 16 and reading and executing the program code recorded on the recording medium by the computer (or CPU or MPU).

  Examples of the recording medium include, for example, a tape system such as a magnetic tape and a cassette tape, a magnetic disk such as a floppy (registered trademark) disk / hard disk, and an optical disk such as a CD-ROM / MO / MD / DVD / CD-R. Card system such as IC card, IC card (including memory card) / optical card, or semiconductor memory system such as mask ROM / EPROM / EEPROM / flash ROM.

  The servo DSP 16 may be configured to be connectable to a communication network, and the program code may be supplied via the communication network. The communication network is not particularly limited. For example, the Internet, intranet, extranet, LAN, ISDN, VAN, CATV communication network, virtual private network, telephone line network, mobile communication network, satellite communication. A net or the like is available. Also, the transmission medium constituting the communication network is not particularly limited. For example, even in the case of wired such as IEEE 1394, USB, power line carrier, cable TV line, telephone line, ADSL line, etc., infrared rays such as IrDA and remote control, Bluetooth ( (Registered trademark), 802.11 wireless, HDR, mobile phone network, satellite line, terrestrial digital network, and the like can also be used. The present invention can also be realized in the form of a computer data signal embedded in a carrier wave in which the program code is embodied by electronic transmission.

  The present invention can also be realized in the form of a computer data signal embedded in a carrier wave in which the program code is embodied by electronic transmission.

  Thus, in this specification, the means does not necessarily mean physical means, but includes cases where the functions of the means are realized by software. Further, the function of one means may be realized by two or more physical means, or the functions of two or more means may be realized by one physical means.

  An optical pickup control apparatus according to the present invention controls an optical pickup that reads and / or writes information by irradiating a light beam to an arbitrary recording medium such as a magneto-optical disk in addition to an optical disk. It can be applied to the device.

It is a block diagram which shows the principal part structure of the optical disk recording / reproducing apparatus common to embodiment of this invention. It is a perspective view which shows the principal part structure of the optical pick-up in the said optical disk recording / reproducing apparatus. It is a block diagram which shows schematic structure regarding the focus servo and spherical aberration servo in the said optical disk recording / reproducing apparatus. It is a block diagram which shows schematic structure regarding the tracking servo in the said optical disk recording / reproducing apparatus. 1 is a block diagram showing a schematic configuration of a servo controller in a servo DSP of an optical disc recording / reproducing apparatus according to an embodiment of the present invention. FIG. It is a graph which shows an example of the correspondence of the position of the collimating lens in the optical pick-up of the said optical disk recording / reproducing apparatus, and an aberration error signal. It is a flowchart which shows the flow of a process until it moves the said collimating lens from the initial position to the position corresponding to the selected recording layer in an optical disk. It is a flowchart which shows the flow of a process of the spherical aberration servo performed after the process shown by FIG. It is a block diagram which shows schematic structure of the servo controller in the servo DSP of the optical disk recording / reproducing apparatus which is another embodiment of this invention. 4 is a flowchart showing a processing flow until an optical pickup can access a recording layer instructed by a system controller in the optical disc recording / reproducing apparatus. It is a flowchart which shows the flow of a process of the spherical aberration servo in the process shown by FIG. It is a flowchart which shows the flow of the interlayer jump process in the said optical disk recording / reproducing apparatus. It is a graph which shows the time change of various signals at the time of performing an interlayer jump process in the said optical disk recording / reproducing apparatus. It is a graph which expands and shows the period which performs a focus jump in FIG. It is a comparative example of FIG. 13, Comprising: It is a graph which shows the time change of various signals at the time of performing an interlayer jump process. FIG. 16 is an enlarged graph showing a period for performing a focus jump in FIG. It is a functional block diagram of the servo controller in the optical disk recording / reproducing apparatus which is further another embodiment of this invention. It is a graph which shows the threshold value of an aberration error signal required in order to close a tracking servo loop. 3 is a flowchart showing an operation flow in the optical disc recording / reproducing apparatus. FIG. 4A is a diagram showing the time taken for the interlayer jump in the conventional optical disc apparatus, and FIG. 4B is the diagram showing the time taken for the interlayer jump in the optical disc recording / reproducing apparatus of the present invention. . It is a functional block diagram of the servo controller of the optical disk recording / reproducing apparatus which is further another embodiment of this invention. It is a functional block diagram of the servo controller in the optical disk recording / reproducing apparatus which is further another embodiment of this invention. It is a figure showing the change of the position of a collimating lens at the time of interlayer jump in the above-mentioned optical disc recording / reproducing apparatus, and an aberration error signal. FIGS. 7A to 7C are graphs showing changes in various signals at the time of interlayer jump in the optical disc recording / reproducing apparatus. 3 is a flowchart showing an example of an operation flow in the optical disc recording / reproducing apparatus. 10 is a flowchart showing another example of the operation flow in the optical disc recording / reproducing apparatus. It is a graph which shows the relationship between the position of the collimating lens in the said optical disk recording / reproducing apparatus, and the gain of a focus servo. It is a graph which shows the relationship between the position of a collimating lens, and an aberration error signal. It is a functional block diagram of the servo controller of the optical disk recording / reproducing apparatus which is further another embodiment of this invention. It is a block diagram which shows schematic structure of the servo controller of the optical disk recording / reproducing apparatus which is another embodiment of this invention. It is a figure which shows the relationship between the position of the collimating lens in the said optical disk recording / reproducing apparatus, an aberration error signal, and the aberration determination signal. It is a flowchart which shows the flow of a process of the spherical aberration servo in the said optical disk recording / reproducing apparatus. It is a block diagram which shows schematic structure regarding the focus servo and spherical aberration servo in the optical disc recording / reproducing apparatus which is another embodiment of this invention. 5 is a graph showing temporal changes of various signals when a light beam passes through a black dot of an optical disc in the optical disc recording / reproducing apparatus. FIG. 35 is a comparative example of FIG. 34, and is a graph showing temporal changes of various signals when a light beam passes through a black dot of an optical disc in the optical disc recording / reproducing apparatus shown in FIG. It is a block diagram which shows schematic structure of the servo controller in the servo DSP of the optical disk recording / reproducing apparatus which is further another embodiment of this invention. It is the schematic which shows the structure of the servo controller with which the optical disk recording / reproducing apparatus which is another embodiment of this invention is provided. It is a flowchart which shows the flow of the focus drawing-in process in the said optical disk recording / reproducing apparatus. This is for explaining the effect of the optical disc recording / reproducing apparatus. FIG. 5A shows the waveform of a focus error signal in the conventional optical disc recording / reproducing apparatus, and FIG. It is a figure which shows the waveform of the focus error signal in an optical disk recording / reproducing apparatus. It is the schematic which shows the structure of the servo controller with which the optical disk recording / reproducing apparatus which is another embodiment of this invention is provided. It is a graph which shows the change of the voltage of the aberration error signal obtained when a collimating lens is moved in the state where the L0 layer or the L1 layer is in focus. It is a flowchart which shows the flow of the focus drawing-in process in the said optical disk recording / reproducing apparatus. 5 is a graph showing an example of a correspondence relationship between a position of a collimating lens and two aberration error signals in a method of correcting spherical aberration by moving the collimating lens in the optical axis direction.

Explanation of symbols

1 Optical disc 7 Optical pickup 16 DSP for servo (control device for optical pickup)
26 Collimating lens (optical element)
27 Collimating lens drive mechanism (aberration correction means)
30 Optical disk recording / reproducing apparatus (optical disk apparatus)
33 Stepping motor (aberration correction means)
100 Aberration error signal acquisition unit (aberration error signal acquisition means)
101 Count acquisition unit (change amount acquisition means)
102 Aberration correction control unit (aberration correction control means)

Claims (12)

An optical pickup control apparatus that controls an optical pickup including an aberration correction unit that corrects spherical aberration generated in the optical system by changing an optical element in the optical system,
Aberration error signal acquisition means for acquiring the spherical aberration as an aberration error signal;
Change amount acquisition means for acquiring a change amount from an initial state of the optical element;
An optical pickup control apparatus comprising: an aberration correction control unit that controls the aberration correction unit based on the aberration error signal when the amount of change is within a predetermined range.   The aberration correction control unit controls the aberration correction unit to change the optical element from the initial state to a state corresponding to the recording layer of the optical disc on which the optical system condenses, and changes after the change. 2. The optical pickup control device according to claim 1, wherein when the amount is within the predetermined range, the aberration correction unit is controlled based on the aberration error signal.   When the aberration correction control unit controls the aberration correction unit based on the aberration error signal, the aberration correction unit does not perform control such that the change amount is out of the predetermined range. The control apparatus for an optical pickup according to claim 1 or 2.   2. The optical pickup control apparatus according to claim 1, wherein the predetermined range is a range in which the value of the aberration error signal monotonously decreases with respect to the amount of change.   5. The control of the optical pickup according to claim 4, wherein the predetermined range has a change amount when the value of the aberration error signal is equal to a target value for correcting the spherical aberration as a median value of the predetermined range. apparatus.   2. The optical pickup control apparatus according to claim 1, wherein the aberration correction unit includes a stepping motor that moves the optical element stepwise from an initial position in an optical axis direction. An optical pickup control apparatus that controls an optical pickup including an aberration correction unit that corrects spherical aberration generated in the optical system by changing optical elements in the optical system stepwise.
Aberration error signal acquisition means for acquiring the spherical aberration as an aberration error signal;
Aberration correction control means for comparing the value of the aberration error signal with the target value for correcting the spherical aberration, and controlling the aberration correction means to change the optical element stepwise based on the comparison result And a control device for an optical pickup. An optical pickup that records and / or reproduces information by irradiating an optical disk with an optical beam, and includes an aberration correction unit that corrects spherical aberration generated in the optical system by changing an optical element in the optical system. With an optical pickup,
An optical disc apparatus comprising: the optical pickup control device according to claim 1. An optical pickup control method comprising an aberration correction means for correcting spherical aberration generated in the optical system by changing an optical element in the optical system,
An aberration error signal acquisition step for acquiring the spherical aberration as an aberration error signal;
Obtaining a number of stages of change from an initial state of the optical element; and
And a aberration correction control step of controlling the aberration correction means based on the aberration error signal when the number of steps is within a predetermined range. A method for controlling an optical pickup comprising aberration correction means for correcting spherical aberration generated in the optical system by changing optical elements in the optical system stepwise,
An aberration error signal acquisition step for acquiring the spherical aberration as an aberration error signal;
Aberration correction control step of comparing the value of the aberration error signal with the target value for correcting the spherical aberration, and controlling the aberration correction means to change the optical element stepwise based on the comparison result And a method for controlling an optical pickup.   8. An optical pickup control program for causing a computer to execute each means in the optical pickup control device according to claim 1.   A computer-readable recording medium on which the optical pickup control program according to claim 11 is recorded.

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