CN100407301C - Optical disc recording/reproducing apparatus, its focusing method, and optical disc recording medium - Google Patents

Abstract

The present invention relates to an optical disc recording/reproducing apparatus, a focusing method thereof, and an optical disc recording medium, wherein there is provided a focus jump part (DSP (51)) according to A recording/reproducing operation performs a focus jump for moving a beam spot from one recording layer to another recording layer of a multilayer optical disc (10) having a plurality of recording layers. The focus jump part performs acceleration for moving the objective lens (34) installed in the optical pickup to move its focal point from one recording layer to another recording layer of the multi-layer optical disc, waits, and performs acceleration for stopping the objective lens deceleration.

Description

Optical disc recording/reproducing apparatus, its focusing method, and optical disc recording medium

The patent application of the present invention is a divisional application of the invention patent application with the international filing date of July 26, 2002, the application number 02814627.1, and the invention title of "optical disc recording/reproducing device, its focusing method, and optical disc recording medium".

Background technique

The present invention relates to an optical disc (disc) recording/reproducing apparatus and method.

In particular, the present invention relates to a technique for stably and reliably performing a focus jump operation in an optical disc recording/reproducing apparatus (optical disc drive) capable of Data is recorded/reproduced on an optical disc, and the focus jump operation is used to move between recording layers.

In an optical disc drive (optical disc recording/reproducing apparatus) capable of recording/reproducing on a multilayer optical disc having a plurality of recording layers, a focus jump operation is used to move a beam spot between recording layers. This focus jump operation combines acceleration pulses and deceleration pulses to move the objective lens (objective lens), thereby moving the beam spot at high speed between recording layers. This operation method is basically similar to the tracking jump operation for moving between tracks in tracking servo control. It should be noted that the jump direction of the focus jump operation is the jump between recording layers along the focus direction, which is different from the track jump.

The following explains the track jump operation also performed in the embodiment of the optical disc recording/reproducing apparatus of the present invention. As shown in Fig. 1A, in the track jump operation, the tracking error signal TE changes in a sine wave state, using time as a variable, therefore, the position of the beam spot relative to the target track can be correctly known, and the acceleration/ time to slow down,

The pulse waveform shown in Fig. 1 B shows for example: in order to drive the coaxial actuator 35 shown in Fig. The executor 35 sends out the acceleration pulse ACCE as the tracking jump drive signal TJ _drv to accelerate the objective lens 34 through the coaxial actuator to move in the tracking direction. Then, the tracking control part in the DSP 51 sends a deceleration to the tracking driver 57. Pulse DECCE, as the tracking jump driving signal TJ _drv , decelerates the movement of the objective lens 34 in the tracking direction.

In the focus jump operation for making the beam spot output by the objective lens 34 jump between a plurality of recording layers of the optical disc, as shown in FIGS. In the (n+1)th recording layer (n+1)L, it is not easy to observe (detect) changes in the focus error signal TE and the summation signal RF except in the vicinity of the recording layer. Outside of this vicinity, it is difficult to accurately time the acceleration/deceleration of the coaxial actuators to stabilize the focus jump. Thus, as shown in FIG. 2C , the focus jump control part sends an acceleration pulse ACCE for driving the coaxial actuator at time t1 as the focus jump drive signal FJ _drv , at this time predicting the moving speed of the objective lens, and, when When the focus error signal FE exceeds the threshold FE _th , a deceleration pulse DECCE for driving the coaxial actuator 35 is issued as a focus jump drive signal FJ _drv at time t2 after a predetermined time elapses. That is, the focus jump control part uses the prediction to accelerate and decelerate the coaxial actuator near the target recording layer of the optical disc to perform the focus jump.

A disc drive (optical disc recording/reproducing apparatus) having a focus jump function is already on the market as a DVD (Digital Versatile Disc) video player, wherein the disc drive executes a control method by such prediction. Techniques disclosed in, for example, Japanese Unexamined Patent Publication (kokai) No. 10-143872, International Patent Publication No. WO98/05032 and the like have been used.

The technique disclosed in Japanese Unexamined Patent Publication (kokai) No. 10-143872 employs a technique of estimating the movement speed of an objective lens mounted on an optical pickup, from the focus error on the initial recording layer before the focus jump When a certain level is exceeded to when it exceeds a certain threshold on the target recording layer is evaluated and a braking pulse as shown in Figures 2A-2C is generated.

However, in the technique disclosed in Japanese Unexamined Patent Publication (kokai) No. 10-143872, when an optical disc whose distance between recording layers deviates from a reference value is loaded in an optical disc recording/reproducing apparatus, the An error occurs in the estimated movement speed of the objective lens, and therefore, focus jump may become unstable.

International Patent Publication No. WO98/05032 discloses a technique for determining the amplitude of a braking pulse from the maximum value of a differential of a focus error signal.

In Japanese Unexamined Patent Publication (kokai) No. 10-143872 and International Patent Publication No. WO98/05032, the reflectance in each recording layer of an optical disc is properly managed. These are techniques performed in DVD-Video players in which a good S-curve is obtained for focus error in each of a plurality of recording layers. However, in a disk drive system in which the numerical aperture (NA) of the objective lens is increased to achieve higher density, the effect of aberrations due to variations in the substrate thickness of the optical disk becomes larger. For example, as shown in Figure 3A, when the numerical aperture (NA) is small, an S-curve with symmetrical positive and negative characteristics is obtained for the focus error, but, as shown in Figure 3B, when the NA is large, the S-curve's Positive and negative characteristics sometimes become asymmetrical. As shown in FIG. 3B, when the S-curve becomes asymmetric between positive and negative, switching timing of acceleration and deceleration of the coaxial actuator for moving the objective lens 34 in the focusing direction cannot be correctly determined.

Furthermore, in a writable optical disc drive for recording/reproduction, the reflectance in each recording layer of the optical disc also varies, so, as in tracking control, for determining the same value by referring to the value of the S-curve of the focus error With the method of deceleration time of the axis actuator, it is impossible to achieve a stable focus jump operation.

Contents of the invention

An object of the present invention is to provide an optical disc recording/reproducing apparatus and method using an optical disc having a plurality of recording layers, even when the waveform of the S-curve of the focus error signal changes due to aberration or at the level of the S-curve. The apparatus and method also enable a stable focus jump operation in the case of changes due to changes in reflectivity in multiple recording layers of the optical disc, where aberrations are caused by changes in the substrate thickness of the optical disc.

The present invention provides an optical disc recording/reproducing apparatus having a focus actuator for performing a focus jump operation corresponding to a recording/reproduction operation for making a laser beam spot with multiple The recording/reproducing operation is used for recording data on the multi-layer optical disc or for reproducing recorded data, and the optical disc recording/reproducing device includes: An optical pickup having an objective lens, a focusing actuator for moving the objective lens in a focusing direction, a light beam emitting part for emitting a light beam, a light receiving part for receiving light returned from the optical disc, and an optical system, the The optical system is used to guide the light beam from the light beam emitting part to the objective lens and guide the return light incident on the objective lens from the optical disc to the light receiving part; the focus error signal generating part, based on the a signal from the light receiving part to generate a focus error signal; a sum signal generating part to generate a sum signal based on the signal from the light receiving part; and a focus drive control part; wherein the focus drive control part performs the following actions : outputting an acceleration pulse signal to the focus actuator to move the objective lens in the focusing direction so that the beam spot from the objective lens is positioned on the Targeting the recording layer of the multi-layer optical disc, waiting for a first waiting time, when the current value of the current summation signal generated from the return light of the optical disc during the waiting for the first waiting time shows a minimum value, and then passing outputting a signal for decelerating movement of the objective lens to the focus actuator when a value obtained by dividing the current summation signal by the reflectivity information of the recording layer specified by the target recording layer signal exceeds a threshold value. The first deceleration pulse signal, in which the target positioning recording layer signal is recorded in the recording layer of the multi-layer optical disc, waits for a second waiting time, and when the return light of the optical disc is generated while waiting for the second waiting time, When the absolute value of the focus error signal shows a maximum value and then crosses zero, a second deceleration pulse for stopping movement of the objective lens is output to the focus actuator.

Description of drawings

The above and other objects and features of the present invention will become more apparent from the following description in conjunction with the accompanying drawings.

1A and 1B are waveform diagrams of a tracking error signal and a track jump driving signal in a track jump operation.

2A-2C are waveform diagrams of a focus error signal, a summation signal and a focus jump driving signal in a focus jump operation.

3A and 3B are waveform diagrams of focus error signals when the numerical aperture is not large and when the numerical aperture is large in the focus jump operation.

4 is a configuration diagram of a multilayer optical disc recording/reproducing apparatus (disk drive) as a basic embodiment of the optical disc recording/reproducing apparatus of the present invention.

FIG. 5 is a view showing a cross-sectional configuration of the multilayer optical disc shown in FIG. 4 and a focus jump state of a beam spot.

FIG. 6 is a view showing phase compensation processing performed by a digital signal processor (DSP) shown in FIG. 4 in a block configuration.

7 is a flowchart of focus control processing executed after the optical disc is loaded in the multilayer optical disc recording/reproducing apparatus (disk drive) shown in FIG. 4 as the first embodiment of the present invention.

8A-8C are graphs of changes in the focus error signal, summation signal and focus drive signal in the focus jump (focus pull-in) operation of the first embodiment.

9A is a block diagram of a high-frequency phase lead compensation filter used to compensate the focus error signal in the DSP shown in FIG. 4; FIG. 9B is a frequency characteristic diagram of the amplitude and phase of the high-frequency phase lead compensation filter shown in FIG. 9A; Figure 9C shows the case where the focus error (FE) signal does not pass through the high-frequency phase lead compensation filter of Figure 9A (dotted line) and the case where the focus error (FE) signal passes through the high-frequency phase lead compensation filter (solid line) and Fig. 9D is under the situation (dotted line) that the braking pulse signal does not pass through Fig. ) waveform diagram.

FIG. 10 is a flowchart of focus control processing as a second embodiment of the present invention.

11A-11C are waveform diagrams of a focus error signal, a summation signal, and a focus jump drive signal in the focus jump operation of the second embodiment.

FIG. 12 is a flowchart of focus control processing as a third embodiment of the present invention.

13A-13C are waveform diagrams of a focus error signal, a summation signal, and a focus jump drive signal in the focus jump operation of the third embodiment.

Fig. 14 is a diagram schematically showing a cross-sectional structure of a multilayer optical disc in a fourth embodiment of the present invention.

15A-15B are diagrams for explaining the method of calculating the sum signal level in each recording layer of the optical disk shown in FIG.

FIG. 16 is a flowchart of focus control processing in the fourth embodiment of the present invention.

17A-17C are a focus error signal, a value obtained by dividing the current sum signal by the level of the sum signal in the target recording layer, and a focus jump drive signal in the focus jump operation of the fourth embodiment of the present invention. waveform diagram.

list of reference numbers

10, 10A.. multi-layer disc

21. Spindle motor

30.. Optical pickup

31..Laser Diode (LD)

32.. Photodetector (PD)

33. Optical system

34. Objective lens

35.. Coaxial Actuator

36.. Skid motor

42..LD driver

50.. Servo Board

51..DSP (Digital Signal Processor)

56. Focus drive

57..Track drive

58.. Skid motor driver

59.. Spindle motor driver

60.. Control microcomputer

Detailed ways

According to a first aspect of the present invention, there is provided an optical disc recording/reproducing apparatus for performing a focus jump operation corresponding to a recording/reproducing operation for making a beam spot Moving between multiple recording layers of a multi-layer optical disc, the recording/reproducing operation is used to record data on the multi-layer optical disc or to reproduce data recorded on the multi-layer optical disc, the device includes: (a) an optical pickup, an optical The pickup has an objective lens, a focus actuator for moving the objective lens in a focusing direction, a beam emitting part for emitting a light beam, a light receiving part for receiving light returned from an optical disc, and an optical system for directing the beam emitting part guides the beam of light to the objective lens and guides the return light incident on the objective lens from the optical disc to the light receiving part, and (b) a focus drive control part that outputs a focus drive signal to the focus actuator to move the objective lens in the focus direction , when the focus jump start signal and the target positioning recording layer signal are applied, it is used to position the beam spot of the objective lens to the target positioning recording layer of the multi-layer optical disc, and this part performs focusing to the The device outputs a first deceleration pulse, and the focus error signal and the sum signal are obtained according to the moving position of the objective lens driven by the focus actuator.

According to a second aspect of the present invention, there is provided an optical disc recording/reproducing method for performing a focus jump operation corresponding to the recording/reproducing operation, the focus jump operation being used to make the beam spot Moving between a plurality of recording layers of a multi-layer optical disc, a recording/reproducing operation is used for recording data on the multi-layer optical disc or for reproducing data recorded on the multi-layer optical disc, the method comprising: (a) outputting to a focus actuator The step of focusing the drive signal, so that the objective lens moves in the focus direction, when the focus jump start signal and the target positioning recording layer signal are applied, for positioning the beam spot of the objective lens to the target positioning recording layer of the multilayer optical disc, and ( b) A step of outputting a first deceleration pulse to a focus actuator by interrogating a focus error signal and a sum signal obtained from a shifted position of an objective lens driven by the focus actuator.

According to a third aspect of the present invention, there is provided an optical disc recording/reproducing apparatus for performing a focus jump operation corresponding to the recording/reproducing operation, the focus jump operation being used to make the beam spot Moving between multiple recording layers of a multi-layer optical disc, the recording/reproducing operation is used to record data on the multi-layer optical disc or to reproduce data recorded on the multi-layer optical disc, the device includes: (a) an optical pickup, an optical The pickup has an objective lens, a focus actuator for moving the objective lens in a focusing direction, a beam emitting part for emitting a light beam, a light receiving part for receiving light returned from an optical disc, and an optical system for directing the beam emitting part guides the beam of light to the objective lens and guides the return light incident on the objective lens from the optical disk to the light receiving part, and (b) a focus drive control part that outputs an acceleration pulse signal to the focus actuator to move the objective lens in the focus direction , when the focus jump start signal and the target positioning recording layer signal are applied, the beam spot of the objective lens is positioned to the target positioning recording layer of the multi-layer optical disc, the first waiting time is precisely waited, and output to the focus actuator for stopping the movement of the objective lens The first deceleration pulse signal.

According to a fourth aspect of the present invention, there is provided an optical disc recording/reproducing method for performing a focus jump operation corresponding to the recording/reproducing operation, the focus jump operation being used to make the beam spot Moving between a plurality of recording layers of a multi-layer optical disc, a recording/reproducing operation is used for recording data on the multi-layer optical disc or for reproducing data recorded on the multi-layer optical disc, the method comprising: (a) outputting to a focus actuator The step of accelerating the pulse signal, so that the objective lens moves in the focus direction, and the beam spot of the objective lens is positioned to the target positioning recording layer of the multilayer optical disc when the focus jump start signal and the target positioning recording layer signal are applied; (b) precisely A step of waiting for a first waiting time; and (c) outputting a first deceleration pulse signal for stopping movement of the objective lens to the focus actuator.

According to a fifth aspect of the present invention, there is provided an optical disc recording/reproducing apparatus for performing a focus jump operation corresponding to the recording/reproducing operation, the focus jump operation being used to make the beam spot Moving between multiple recording layers of a multi-layer optical disc, the recording/reproducing operation is used to record data on a multi-layer optical disc and record information on the number of recording layers and the reflectivity of each recording layer on one recording layer, or to reproduce recording data on a multi-layer optical disc, the apparatus includes: (a) an optical pickup having an objective lens, a focusing actuator for moving the objective lens in a focusing direction, a beam emitting part for emitting a light beam, A light receiving part of the returned light, and an optical system for guiding the light beam of the light beam emitting part to the objective lens and guiding the return light incident on the objective lens from the optical disc to the light receiving part; (b) focus error signal generating part , generate a focus error signal based on the signal of the light receiving part; (c) a summation signal generation part, generate a summation signal based on the signal of the light receiving part; and (d) a focus drive control part, which is used to perform The device outputs an acceleration pulse signal to move the objective lens in the focusing direction, and when the focus jump start signal and the target positioning recording layer signal are applied, the beam spot of the objective lens is positioned on the target positioning recording layer of the multi-layer optical disc, and the first time is accurately waited. Waiting time, when the summation signal shows a minimum value during the first waiting process, and then when a value obtained by dividing the current summation signal by the reflectance information of the recording layer specified by the target positioning recording layer signal exceeds a threshold value , outputting the first braking pulse for decelerating the movement of the objective lens to the focus actuator, wherein the target positioning recording layer signal is recorded in the recording layer of the multi-layer optical disc, waiting for the second waiting time exactly, and when When the absolute value of the focus error signal shows a maximum value and then crosses zero during the second waiting period, a second brake pulse for stopping the movement of the objective lens is output to the focus actuator.

According to a sixth aspect of the present invention, there is provided an optical disc recording/reproducing method for performing a focus jump operation corresponding to the recording/reproduction operation, the focus jump operation being used to make the beam spot Moving between multiple recording layers of a multi-layer optical disc, the recording/reproducing operation is used to record data on a multi-layer optical disc and record information on the number of recording layers and the reflectivity of each recording layer on one recording layer, or to reproduce recording For data on a multi-layer optical disc, the method includes: (a) the step of outputting an acceleration pulse signal to a focus actuator to move the objective lens in the focus direction, and when the focus jump start signal and the target positioning recording layer signal are applied, the The beam spot of the objective lens is positioned to the target positioning recording layer of the multi-layer optical disc; (b) the step of accurately waiting for the first waiting time; (c) when the sum signal shows a minimum value during the first waiting process, and then when When the value obtained by dividing the current summation signal by the reflectivity information of the recording layer specified by the target positioning recording layer signal exceeds a threshold value, outputting the first brake pulse for decelerating the movement of the objective lens to the focus actuator step, wherein the target positioning recording layer signal is recorded in the recording layer of the multi-layer optical disc; (d) the step of accurately waiting for the second waiting time; and (e) when the absolute value of the focus error signal during the second waiting process represents A step of outputting a second brake pulse for stopping the movement of the objective lens to the focus actuator when the maximum value is reached and then crosses zero.

According to a seventh aspect of the present invention, there is provided an optical disc recording/reproducing apparatus for performing a focus jump operation corresponding to the recording/reproduction operation, the focus jump operation being used to make the beam spot Moving between a plurality of recording layers of a multi-layer optical disc, the recording/reproducing operation is used for recording data on the multi-layer optical disc or for reproducing data recorded on the multi-layer optical disc, the apparatus is provided with a focus drive control part, the part: applying an acceleration pulse signal to a focusing actuator that moves the objective lens in a focusing direction, for moving the beam spot of the objective lens mounted on the optical pickup from the recording layer where the beam spot is currently located in the multilayer optical disc to a designated recording layer; then , output a deceleration pulse signal to the focusing actuator, and decelerate the movement of the objective lens near the designated recording layer; and, after making the absolute value of the impulse of the acceleration pulse signal greater than the absolute value of the impulse of the deceleration pulse signal, output the acceleration pulse signal Impulse.

According to an eighth aspect of the present invention, there is provided an optical disc recording/reproducing apparatus having a focus actuator for performing a focus jump operation corresponding to the recording/reproduction operation for making the laser beam spot Moving between a plurality of recording layers of a multi-layer optical disc having a plurality of recording layers, the recording/reproducing operation is for recording data on the multi-layer optical disc or for reproducing recorded data, the apparatus is provided with a focus drive control section which Apply an acceleration pulse signal to the focus actuator to move the beam spot of the objective lens installed on the optical pickup from the recording layer where the beam spot is currently located in the multilayer optical disc to the designated recording layer; after that, it acts on the focus actuator a first deceleration pulse signal; and, when the focus error signal becomes not greater than a certain level on the target recording layer, a second deceleration pulse signal is applied.

According to a ninth aspect of the present invention, there is provided a writable or read-only optical disc recording medium formed by stacking a plurality of recording layers, wherein the optical disc recording medium is characterized in that: the total number of recording layers of the optical disc recording medium is recorded in a predetermined in the area.

According to a tenth aspect of the present invention, there is provided a writable or read-only optical disc recording medium formed by laminating a plurality of recording layers, wherein the optical disc recording medium is characterized in that: reflection when the beam spot is focused on each recording layer The rate is recorded in a predetermined area of the disc in advance.

Preferred embodiments of the optical disc (disk) recording/reproducing apparatus and method of the present invention are explained below with reference to the accompanying drawings.

basic terms

Before describing the preferred embodiments of the present invention, basic terms and conditions of the optical disc recording/reproducing apparatus and method of the embodiments of the present invention are explained.

Condition 1. In order to prevent the influence of the S-curve level fluctuation on the focus error signal, for the focus jump, the acceleration and deceleration time of the actuator used to move the position of the objective lens (objective lens) and the amplitude of the pulse are determined in advance, and the summation is considered The level of the signal RF.

Furthermore, the impulse of the acceleration pulse acting on the objective lens is slightly larger than the impulse of the deceleration pulse. At the end of the deceleration pulse, the beam spot approaches the target recording layer (layer) in a state where the velocity is sufficiently reduced.

"Impulse" refers to the value obtained by multiplying the pulse duration by the pulse amplitude. "Impulse" refers to the change in velocity of the objective lens driven by the coaxial actuator.

Condition 2. In order to make the movement speed of the objective lens close to 0 when the focus error becomes a certain level or less (slightly ahead of the focus position), a deceleration pulse (brake pulse) is applied to the actuator for moving the objective lens .

The impulse of the deceleration pulse (braking pulse) is the value obtained by dividing the differential of the S-curve of the focus error signal by the level of the summation signal RF, that is, this value is the same as the arrival speed of the beam spot of the objective lens when it reaches the target recording layer of the optical disc Proportionally, wherein a focus jump must be performed on the disc. Due to the influence of aberration, etc., there may be a slight deviation between the braking pulse and the optimum value, but the movement speed of the objective lens has dropped at this time, so that, by the normal focus servo control performed after the focus jump operation ends, This deviation can be absorbed.

According to conditions 1 and 2, in such a high-density writable multi-layer disc, the beam spot can move stably between recording layers, wherein, in this disc, the interlayer distance between a plurality of recording layers of the disc is the same as the reference The values vary, or a constant S-curve cannot always be obtained around each recording layer.

Furthermore, it is also possible to stabilize the focus pull-in operation by applying a value proportional to the differential of the focus error signal, as a braking pulse, to the actuator for moving the objective lens.

In this description, the operation of making the beam spot of the objective lens jump from a certain recording layer to another recording layer of an optical disc having multiple recording layers is called a "focus jump operation", and the beam spot is focused on the target recording layer The moment of is called "end of focus introduction".

After focus pull-in, control is transferred to conventional focus servo control. Focus servo control is performed by existing circuits and existing methods. Accordingly, in this description, the control for performing focus jump control and performing focus pull-in is mainly explained.

Further, in the optical disc recording/reproducing apparatus of the present invention, tracking servo control is performed during the focus jump operation, but tracking servo control is not the subject of the present invention, and thus its detailed description is omitted. In the same manner, in the optical disk recording/reproducing apparatus of the present invention, a track jump operation is performed by driving the sled motor while performing focus servo control, but a detailed description thereof is omitted.

first embodiment

The first embodiment of the optical disc recording/reproducing apparatus and method of the present invention is explained with reference to FIGS. 4 to 9A-9D.

4 is a configuration diagram of a multilayer optical disc recording/reproducing apparatus (disk drive) of a basic embodiment of the optical disc recording/reproducing apparatus of the present invention.

The optical disc recording/reproducing apparatus has an optical pickup 30 , a servo board 50 , a spindle motor 21 , a turntable 22 , a chucking plate 23 , a laser diode (LD) driver 42 , and a summing signal amplifier 41 .

FIG. 5 is a view showing a cross-sectional configuration of the multilayer optical disc shown in FIG. 4 and a focus jump state of a beam spot.

The multilayer optical disc 10 shown in FIG. 4 is a double-layer disc having two information recording layers as shown in FIG. recording layer 13 , and a light-transmitting cover layer 15 . 5 shows a state in which the beam spot of the objective lens 34 is irradiated to the first recording layer 13 indicated by a solid line, and a state in which the focus of the beam spot of the objective lens 34 has shifted to the second recording layer 12 is indicated by a dotted line.

The multi-layer optical disk 10 is loaded into the turntable 22 and fixed with the clamping plate 23 , wherein the turntable 22 is connected to the spindle motor 21 . The control microcomputer 60 performs information recording/reproduction on the optical disc 10 rotationally driven by the spindle motor 21 through the optical pickup 30 .

The optical pickup 30 includes an optical system 33; an objective lens 34; a coaxial actuator 35 for driving the objective lens 34 in a focusing direction and a tracking direction; Optical elements of detector (PD) 32, beam splitter BS and collimator lens CL.

Instead of the coaxial actuator 35, it is also possible to configure the actuators as a first actuator for driving the objective lens 34 in the focusing direction and a second actuator for moving the objective lens 34 in the orbital direction, respectively.

The gist of the present invention is to make the beam spot of the objective lens 34 perform focus jump among multiple recording layers of the multilayer optical disc 10 . The following description focuses on the driving of the coaxial actuator 35 in the focusing direction or the driving of the first actuator.

Under the control of a digital signal processor (DSP) 51 , the sled motor 36 is driven by a sled motor driver 58 to move the optical pickup 30 in a direction intersecting the track of the optical disc 10 .

The photodetector 32 is, for example, a two-part or four-part photodetector. A focus error signal FE, a tracking error signal TE and a sum signal RF are generated from the detection signals of the two-part or four-part detectors.

The servo board 50 is a circuit board on which the following components are mounted: a focus error processor 51A, a sum signal processor 51B, a tracking error processor 51C, three first low-pass filters ( LPF) 52, three parallel-connected analog/digital conversion circuits (ADC) 53, digital signal processor (DSP) 51, three parallel-connected digital/analog conversion circuits (DAC) 54, three parallel-connected second Low-pass filter (LPF) 55, focus driver 56 for driving coaxial actuator 35 in focusing direction, tracking driver 57 for driving coaxial actuator 35 in tracking direction, sled motor 36 for driving The sled motor driver 57, the spindle motor driver 59 for driving the spindle motor 21, and the control microcomputer 60.

The servo board 50 refers to a board including the above circuit elements mounted on one or more circuit boards. The circuit components mounted on the servo board 50 do not always have to be mounted on the circuit board, and may be arranged individually. Conversely, it is also possible to mount on the servo board 50 the LD driver 42 and the summing signal (RF) amplifier 41 which are not mounted on the servo board 50 .

The output of the photodetector 32 is supplied to an RF amplifier circuit (RF amplifier) 41 for amplifying the summation signal RF, and simultaneously supplied to a servo board 50 . By processing the focus error processor 51A, the focus error signal FE is generated from the output of the photodetector 32 input to the servo board 50, the sum signal RF processed by the sum signal processor 51B is generated, and the tracking error processor 51C processes And a tracking error signal TE is generated.

High-frequency components of the three generated signals FE, RF and TE are eliminated in three low-pass filters (LPF) 52 arranged in parallel, and low-frequency components are passed. Furthermore, the passed low-frequency components are converted into digital signals in three AD converters (ADC) 53 arranged in parallel, and the converted digital signals are output to the DSP 51 for high-speed processing.

As explained in FIG. 6, the DSP 51 executes a control process of starting a focus jump operation based on a focus jump start command output from the control microcomputer 60, and performs phase compensation on the focus error signal FE and the tracking error signal TE (refer to FIG. 9A). Preferably, the DSP 51 performs a control process for the focus jump operation based on the values of the phase-compensated focus error signal FE and the sum signal RF. That is, the DSP 51 functions as the focus jump processing part of the present invention in addition to functioning as the above-mentioned phase compensation processing part. In this embodiment, the control microcomputer 60 performs overall control of the optical disk recording/reproducing apparatus. Focus control processing required for high-speed processing is performed by the DSP 51, and the focus control processing includes focus jump operation and phase compensation processing.

Three DA converters (DAC) 54 arranged in parallel convert the digital output signal of the DSP 51 into an analog signal. Low-frequency components of the focus error signal FE and the tracking error signal TE that have been phase-compensated and converted into analog signals are extracted in respective low-pass filters (LPFs) in the three LPFs 55 arranged in parallel.

The low-frequency components of the phase-compensated focus drive signal F _drv , tracking drive signal TR _drv and sled motor drive signal SM _drv in the DSP 51 are applied to the focus driver 56 , tracking driver 57 and sled motor driver 58 to drive the coaxial Actuator 35 and sled motor 36.

The coaxial actuator 35 positions the beam spot collected by the objective lens 34 on a desired recording layer of the optical disc 10, and moves the beam spot to a desired track. The sled motor 36 moves the optical pickup 30 in the track direction in large increments.

The spindle motor driver 59 rotates the spindle motor 21 under the control of the control microcomputer 60 . The rotation of the spindle motor 21 is determined by the optical disc 10, such as a constant linear velocity system optical disc or a constant angular velocity system optical disc.

FIG. 6 is a view showing phase compensation processing performed by a digital signal processor (DSP) shown in FIG. 4 in a block diagram configuration.

The DSP 51 for performing phase compensation has a first phase compensating section 511 for phase compensating the focus error signal FE, a second phase compensating section 512 for phase compensating the tracking error signal TE, and a phase compensating section 512 based on the sum signal RF and the focus error Timing signal generation unit 513 for generating focus start and focus jump timing signals from signal FE.

The DSP 51 has a first switch 514 which routinely switches between the focus error signal FE, the focus jump signal FJ and the focus search signal FS according to the timing signal of the timing signal generating part 513, and outputs the selected signal to the connection to the DAC of the focus driver 56, wherein the focus error signal FE has been phase-compensated in the first phase compensation part 511. The DSP 51 has a second switch 515 which routinely switches between the tracking error signal TE and the tracking jump signal TJ according to a single rotation signal 1ROT or a track jump command TJ, and outputs the selected signal to a track driver connected to 57 DAC, wherein the tracking error signal TE has undergone phase compensation in the second phase compensation unit 512 .

The DSP 51 has a low-frequency component boost filter (LBF) section 516 that performs low-frequency component boost filter processing on the tracking error signal TE that has been phase-compensated in the second phase compensating section 512, so as to extract only low-frequency components and convert the The ingredients are output to the sled motor driver 58.

Output signals of the first switch 514, the second switch 515, and the low-frequency component boosting filter (LBF) section 516 are converted from digital signals to analog signals in three DA converters (DACs) 54 arranged in parallel. The resulting drive signal passes through three low-pass filters (LPF) 55 arranged in parallel, and then the low-frequency components are sent to the corresponding drivers, namely focus driver 56 , tracking driver 57 and sled motor driver 58 . Under the control of the control microcomputer 60 , the optical disc 10 is rotationally driven by operating the spindle motor driver 59 . For the optical disc 10 rotated in this way, the sled motor driver 58 drives the sled motor 36 to move the optical pickup 30 in the track direction of the optical disc 10, and at the same time, the focus driver 56 and the tracking driver 57 drive the coaxial actuator 35, Focus servo control and tracking servo control are performed on the beam spot of the objective lens 34 .

The control microcomputer 60 communicates the target rotation speed to the spindle motor driver 59 so that the rotation speed of the optical disk 10 is controlled by the spindle motor 21 .

Tracking control of the objective lens 34 and track jumping control using the sled motor 36 are not the subject of the present invention, and thus detailed descriptions are omitted. An overview of tracking control has been given above in connection with Figures 1A-1B.

7 is a flow chart of the focus pull-in (focus jump) operation of the first embodiment of the present invention performed by the DPS 51 after the optical disc is loaded in the multilayer optical disc recording/reproducing apparatus (disk drive) shown in FIG. 4.

8A-8C are graphs of changes in the focus error signal FE, the sum signal RF, and the focus jump drive signal FJ _drv at the time of focus pull-in of the first embodiment.

Step S1: Start focus import operation

When a focus pull-in (focus jump) start command is received from the control microcomputer 60 at time t1 in FIG. 8C, the DPS 51 outputs a focus jump drive signal FJ _drv to the focus driver 56, which increases with a slope of a constant gradient, as shown in FIG. 8C As shown, thereby, the objective lens 34 gradually approaches the optical disc 10 . Through this, the focus jump drive signal FJ _drv is applied from the focus driver 56 to the coaxial actuator 35, and the coaxial actuator 35 moves the objective lens 34 in the focusing direction. The photodetector 32 detects the signal according to the motion of the objective lens 34, the focus error signal generating unit (processor) 51A generates a focus error signal FE as shown in FIG. 8A from the detection signal of the photodetector 32, and the sum signal generating unit ( A processor) 51B generates a summation signal RF as shown in FIG.

Considering the inertia, response, etc. of the objective lens 34 and the coaxial actuator 35, the gradient of the focus jump drive signal FJ _drv is controlled to a certain value. By this value, the response will not be reduced due to the slow movement speed of the objective lens 34, and the beam spot will not be reduced. Because the objective lens 34 moves too fast and surpasses the target recording layer.

Steps S2-S5: focus jump processing

When the DSP 51 detects that the focus error signal FE has exceeded the predetermined level FEon (S2) at time t2 of FIG. 8A and the summed signal RF has exceeded the level PIon (S3) at time t3 of FIG. When the focus error signal FE crosses zero (ZC) at time t4 in FIG. 8A and its absolute value becomes smaller than the zero-cross threshold FEzc (S4), the DSP 51 calculates the differential (dFE/dt) of the focus error signal FE at time t4. ), and output the first brake pulse signal BRK1 (or the first deceleration pulse DECCE1) to the focus driver 56 at time t5 in FIG. 8C for a certain time Δtbrk (S5), wherein the first brake pulse signal The amplitude Abrk=kx(dFE/dt) (k is a proportionality constant) is proportional to the differential, and the time t5 is almost the same as the time t4. By doing this, the movement of the objective lens 34 is stopped.

The first brake pulse signal BRK1 is a signal for stopping the movement of the objective lens 34 . A pulse signal having an impulse is produced according to the movement acceleration of the objective lens 34 at this time, and therefore, BRK1 has an amplitude proportional to the differential (dFE/dt) of the focus error signal FE at time t4.

The polarity of the amplitude of the first brake pulse signal BRK1 is determined according to the polarity of the side where the focus error signal FE crosses zero. For example, when the focus error signal FE crosses zero from the positive polarity side to the negative polarity side, the DSP 51 changes the amplitude polarity of the first brake pulse signal BRK1 to negative polarity. In this way, the DSP 51 always outputs the first brake pulse signal BRK1 to the focus driver 56 in the direction of decreasing the relative speed between the objective lens 34 and the optical disc 10 in the focusing direction.

When the DSP 51 determines the magnitude and polarity of the amplitude of the braking pulse BRK1 through the above method, according to the reflectivity of the recording layer of the optical disc 10, the amplitude of the braking pulse BRK1 Abrk deviates from the optimum point for focus servo. To prevent this, the DSP 51 always prevents this by using Abrk = ((dFE/dt)/(PItn) x kr (kr is a constant of proportionality in the case of using the level of the summation signal RF) and taking into account the voltage of the summation signal RF PItn is equal, and an optimal braking pulse independent of the reflectivity of the recording layer of the optical disc 10 is issued.

Step 6: The focus jump operation ends

Subsequently, when the DSP 51 detects a zero-cross at time t6 while the focus error signal FE of negative polarity is changed to positive polarity, the DSP 51 assumes that the focus jump processing is terminated, closes the focus loop, and shifts to focus servo control. By the focus servo control, the objective lens 34 is controlled (maintained) at the focus jump position.

Steps S7-S8: Also after this, the DSP 51 monitors the state of the optical disc recording/reproducing device, and monitors, for example, the signal level of the summation signal RF. If disturbance such as strong vibration occurs in the disc drive (optical disc recording/reproducing apparatus), the amount of defocus becomes large and the DSP 51 detects at time t7 that the summation signal RF representing the state of the synchronization pull-in level is lower than the level PIoff (S7 ), the DSP 51 outputs the second brake pulse BRK2 with amplitude Aoff to the focus driver 56 at time t8, for as long as the precise time Δtoff (S8), and moves the objective lens 34 away from the optical disc 10 through the coaxial actuator 35, thus The objective lens 34 is prevented from hitting and damaging the optical disc 10, wherein the time t8 is almost the same as the time t7. At this time, the focus servo control is forcibly turned off by the DSP 51.

In the above description, the time Δtbrk of the first brake pulse BRK1 is made constant and the amplitude Abrk is changed, but it is also possible not to change the amplitude but to change the output time Δtbrk of the first brake pulse BRK1 . In this embodiment, the DSP 51 controls the product (impulse) of the output time Δtbrk and the amplitude Abrk of the brake pulse BRK1.

For the value of the impulse (Ark x Δtbrk), when the focus error signal FE becomes lower than the threshold FEzc (time t4), even the amplitude Abrk and the braking time Δtbrk are changed so as to be proportional to the differential (dFE/dt) of the focus error signal ratio, the same effect as above can also be obtained.

Modification of the first embodiment

9A is a block diagram of a high-frequency phase lead compensation filter used to compensate the focus error signal in the DSP shown in FIG. 4; FIG. 9B is a frequency characteristic diagram of the amplitude and phase of the high-frequency phase lead compensation filter shown in FIG. 9A; Figure 9C shows the case where the focus error (FE) signal does not pass through the high-frequency phase lead compensation filter of Figure 9A (dotted line) and the case where the focus error (FE) signal passes through the high-frequency phase lead compensation filter (solid line) and Fig. 9D is under the situation (dotted line) that the braking pulse signal does not pass through Fig. ) waveform diagram.

In the first embodiment, the original focus error signal without signal processing, that is, the FEr without phase compensation, is used to judge the zero-crossing of the focus error signal FE in step 4 at time t4, but for the first embodiment As a modified example, as shown in FIG. 9A, if the focus error signal FEf passed through the high-frequency phase lead compensation filter 511 in the DSP 51 is used, the following advantages are obtained: the overshoot of the focus jump during focusing is reduced.

When the original focus error signal FEr generated in the focus error signal processor 51A is input, the high frequency phase lead compensation filter 511 shown in FIG. 9A outputs the compensated focus error signal FEf, but the filter 511 has the following frequency characteristics : During focus pull-in, the phase leads in the frequency domain of the S-curve, as shown in the amplitude characteristic curve CV1 and phase curve CV2 of FIG. 9B. By passing the original focus error signal FEr through the high-frequency phase lead compensation filter 511, the zero-crossing time tf of the focus error signal FEf after passing through the high-frequency phase lead compensation filter becomes shorter than that of the original focus error signal FEr shown in FIG. 9C. The waveform of the S-curve crosses zero earlier. Accordingly, if the DSP 51 performs zero-cross judgment of the focus error signal FE by using the focus error signal FEf after passing through the high-frequency phase lead compensation filter, the DSP 51 can output The braking pulse BRKf, wherein the braking pulse BRKr is indicated by a dotted line in FIG. 9D and the braking pulse BRKf is indicated by a solid line, thus reduces overshoot after focusing. Also in this case, the differentiation of the focus error signal FEf with an earlier time instant after passing through the high-frequency phase lead compensation filter is intended to be used for calculating the amplitude of the braking pulse BRKf.

The above-explained focus error signal FEf after passing through the high-frequency phase lead compensation filter can also be applied to the following embodiments.

In the first embodiment, by using a method of outputting a value proportional to the differential of the focus error signal at time t4 as the first brake pulse BRK1, the focus pull-in (focus jump) operation is stabilized. It is particularly desirable that, as explained in the modified example of the first embodiment, the zero-crossing is detected and judged at time t4 by using the focus error signal FEf after passing through the high-frequency phase lead compensation filter, and, after passing through the high-frequency phase lead compensation filter The differential of the focus error signal FEf after the detector is used to calculate the braking pulse BRKf.

In the first embodiment, after the focus synchronization pull-in, when disturbance occurs, the defocus becomes larger, and the synchronization pull-in level becomes lower than the level PIoff of the summation signal RF (S8, t7), by the output time The second braking pulse BRK2 ( S8 , t8 ) with exactly Δtoff and amplitude Aoff can prevent the objective lens 34 from colliding with the optical disc 10 .

It can be clearly seen from the description of FIG. 8C that the impulse of the first braking pulse BRK1 is greater than that of the second braking pulse BRK2 to prevent the objective lens 34 from colliding with the optical disc 10 . This is because the amount of movement of the objective lens 34 by the first braking pulse BRK1 is greater than the amount of movement of the objective lens 34 by the second braking pulse BRK2, which is used to separate the objective lens 34 from the optical disc 10 a little.

second embodiment

The second embodiment of the optical disc recording/reproducing apparatus and method of the present invention will be explained below with reference to FIG. 10 and FIGS. 11A-11C.

Fig. 10 is a flow chart of processing from when the control microcomputer 60 shown in Fig. 4 sends a focus jump start command to the DSP 51 until the DSP 51 completes the focus jump. In Fig. 10, steps D1-D3 show that DSP 51 drives the coaxial actuator 35 by focusing driver 56 and make the operation that objective lens 34 moves on the focus direction; Steps S11-S15 show the monitoring/judging process that DSP 51 carries out, And steps T1-T4 show the timer and the timing processing of the DSP 51.

11A-11C are waveform diagrams of the focus error signal FE, the sum signal RF, and the focus jump drive signal FJ _drv in the focus jump operation of the second embodiment.

In the first embodiment, an example of the focus pull-in operation is explained, in which the DSP 51 as the focus drive control part outputs a signal increasing at a constant gradient to the coaxial actuator 35 via the focus driver 56 as the focus jump drive signal FJ _drv , and when the beam spot reaches the target recording layer, the DSP 51 outputs the first braking pulse BRK1 to the coaxial actuator 35 through the focus driver 56 to stop the movement of the objective lens 34, but in the second embodiment, as shown in FIG. 11C As shown, the DSP 51 executes an acceleration step (processing) P1 of outputting an acceleration pulse signal ACCE, a waiting step (processing) P2, and a deceleration step (processing) P3 of outputting a first deceleration pulse signal DECCE to the coaxial actuator 35.

According to the second embodiment, it becomes possible to move the beam spot from the current recording layer to the target recording layer at high speed and stably.

In the second embodiment of the present invention, the DSP 51 shown in FIG. 4 is always kept in the DSP 51 memory not shown during the time when the focus servo loop is off, that is, when the focus jump operation is not performed. The value _{Afd_LPF} of the low-frequency component of the signal FJ _drv obtained by passing the focus jump drive signal FJ _drv through a low-pass filter (LPF) 55 . The value Afd_LPF of the low frequency component is used as an offset value of the focus jump drive signal FJ _drv .

When the DSP 51 receives a focus jump start command from the control microcomputer 60, the DSP 51 as a focus jump section (or a focus driving section) starts focus jump processing.

Step D1: DSP 51 as the focus drive control part of the present invention outputs to the focus driver 56 at time d1 in FIG. The pulse of the value (offset) Afd_LPF of the low frequency component of the focus jump drive signal FJ _drv is used as the acceleration pulse ACCE to accelerate the objective lens 34 in the focus direction by the coaxial actuator 35, and, within the time Δtdrv, The acceleration pulse ACCE is stored in the memory of the DSP 51 (FIG. 11C). In this way, the coaxial actuator 35 moves the objective lens 34 in the focusing direction by an amount corresponding to the value defined by the impulse of the acceleration pulse ACCE.

The offset value Afd_LPF is added to the amplitude Aacce stored in the memory as the acceleration pulse signal ACCE, because without adding this offset value, the objective lens 34 will not move exactly the desired amount.

It should be noted that the present embodiment exemplifies the multilayer optical disc 10 having two recording layers, thus, a single type of amplitude Aacce determined in advance and stored in the memory of the DSP 51 is sufficient, however, when the multilayer optical disc 10 has three When there are two or more recording layers, for the amplitude Aacce stored in the memory, the first amplitude when moving the beam spot in one recording layer and the second amplitude when moving the beam spot between two recording layers are stored in the memory. , and selectively used according to the amount of movement of the objective lens 34.

Steps D2-D3: After outputting the acceleration pulse ACCE for a time of Δtdrv, the focus drive part in the DSP 51 continuously outputs only the value Afd_LPF of the low frequency component of the focus jump drive signal FJ _drv to the focus drive 56 at time d2 as Offset value in wait time Δtwait (D2, Fig. 11C). The focus jump drive signal FJ _drv of the offset value Afd_LPF is output to the coaxial actuator 35 within the waiting time, because by applying the focus jump drive signal FJ _drv of this offset value to the coaxial actuator 35, it actually shows waiting state.

At time d3, the first deceleration pulse DECCE ( D3 ) of exactly Δtdrv is output, the amplitude (Adece−Afd_LPF) of DECCE is obtained by subtracting the offset value Afd_LPF from the initial amplitude Adece.

The DSP 51 outputs an acceleration pulse ACCE and a deceleration pulse DECCE whose values pass the previously determined output amplitudes accurately in all states of the acceleration step P1, the waiting time P2, and the deceleration step P3 of the focus jump cycle shown in FIG. 11C. It is obtained by offsetting the low-frequency component of the focus jump drive signal FJ _drv by the offset value Afd_LPF.

The offset value Afd_LPF is not limited to the value measured within the above waiting time. As explained in the first embodiment, during the focus servo control, the low-frequency component of the aggregated error signal FE measured in advance can also be used.

In the DSP 51, if the amplitude Aacce of the acceleration pulse is set slightly greater than the amplitude Adece of the deceleration pulse so that the impulse of the acceleration pulse ACCE acting on the objective lens 34 becomes slightly greater than the impulse of the deceleration pulse DECCE, then, in the motion of the objective lens 34 The focused laser beam (beam spot) in the state where the speed is sufficiently lowered hits the target recording layer of the optical disc 10, and therefore, the focus jump can be terminated without a large overrun and switching to the focus servo control can be performed.

In the same manner as the focus pull-in time, the DSP 51 as a focus drive control part can adjust the impulse by changing the time or amplitude of the acceleration pulse and the deceleration pulse, or can adjust both the amplitude and the time.

Steps S11-S14: In the same manner as the processing of steps S1-S5 explained in connection with FIG. 7, during the period in which the acceleration/deceleration operation is performed on the objective lens 34, the DSP 51 constantly monitors the focus error signal FE and the summation signal RF (FIG. 11A and FIG. 11B, time t11-t14), and check whether the beam spot emitted from the objective lens 34 moves reliably between the recording layers of the optical disc 10, wherein the focus driver 56 and the coaxial actuator 35 are controlled according to the data from the DSP 51 The acceleration pulse ACCE and the deceleration pulse DECCE shown in FIG. 11C are output to drive the objective lens 34 .

These steps are explained more specifically below. In step S11, the DSP 51 detects at time t11 whether the focus error signal FE becomes larger than the threshold value FEfj. Subsequently, the DSP 51 detects the fact that the deceleration pulse DECCE shown in FIG. 11C is output after the elapse of time d2 after the acceleration pulse ACCE shown in FIG. 11C ends, and the sum signal RF becomes the minimum value at time t12 (step S12).

The DSP 51 detects the fact that the absolute value of the focus error signal becomes larger than the threshold FEfj in step S13, and then the focus error signal FE has a polarity opposite to that at time t11. Further, in step S14, when the DSP 51 detects that the absolute value of the focus error signal FE shows a maximum value, then changes toward zero crossing and the absolute value of the focus error signal FE becomes smaller than the threshold value FEfj_zc at time t14, the DSP 51 judges that the focus jump operation is terminated, and in step S15, the focus loop is closed and shifted to focus servo control.

Step T1-T4 (T1-T4): when starting the focus jump operation, activate the timer in the DSP51, and check whether the DSP 51 as the focus drive control part executes the above steps S11-S14 in the time Tfj_limit determined in advance operation, and, when the operation is not yet terminated, the DSP 51 outputs a braking pulse similar to the second braking pulse BRK2 shown in FIG. , and then return to focus search mode.

According to the above method, it is possible to stably move the beam spot between recording layers even in a high-density writable multilayer disc in which the interlayer distances of the plurality of recording layers of the optical disc 10 are different from the reference The values deviate or a constant S-curve is not always obtained for the focus error signal around each recording layer.

third embodiment

An optical disc recording/reproducing apparatus and method for focus jump as a third embodiment of the present invention will be explained below with reference to FIG. 12 and FIGS. 13A-13C.

FIG. 12 is a flowchart of processing until completion of a focus jump according to the third embodiment.

13A-13C are waveform diagrams of the focus error signal FE, the sum signal RF, and the focus jump drive signal FJdr in the focus jump operation of the third embodiment.

In Fig. 12, in the same manner as Fig. 10, steps D1-D4 show that DSP 51 drives the coaxial actuator 35 and the operation of moving objective lens 34 in the focus direction by focusing driver 56, and steps S11-S15 show that DSP 51 is driven by DSP. The monitoring/judging process performed by 51, and steps T1-T4 show the timer and the timing process performed by DSP 51.

The processing of steps S11-S14, steps D1-D3, and steps T1-T4 in the third embodiment of the present invention shown in FIG. 12 is the same as that of the second embodiment explained with reference to FIG.

The third embodiment is different from the second embodiment explained with reference to FIG. 10 in that when in step S14 of FIG. When it is judged to cross zero, the DSP 51 does not immediately close the focus loop to terminate the focus jump operation and switch to the focus servo control as in the second embodiment, but increases the processing of step D4 at time t14 to focus in a short time Δtbrk2 The driver 56 outputs the second deceleration pulse DECCE2, drives the coaxial actuator 35, and stops the movement of the objective lens 34, wherein, the amplitude Abrk2=dFE/dt x kfj of the second deceleration pulse DECCE2 is proportional to the differential dFE/dt of the focus error signal FE Proportion.

Subsequently, in step S15, the DSP 51 closes the focus loop, and shifts to focus servo control.

Also in the third embodiment, the method of calculating the amplitude Abrk2 of the second deceleration pulse DECCE2 at time t14 of FIG. 13A using the level of the summation signal RF is exactly the same as in the case of the first embodiment. The differential dFE/dt of the focus error signal is divided by the level PILn of the sum signal RF at time t14. This value is multiplied by the proportionality factor kfj_PI to obtain Abrk2=((dFE/dt)/(PILn)xkfj_PI. By using these, it is possible to realize a stable focus jump which is not affected by the reflectivity of the recording layer of the optical disc 10.

Modified example of the third embodiment

Similar to what was explained in the modified example of the second embodiment, also in the third embodiment, after focusing using the focus error signal FEf, it is possible to reduce the overrun of the beam spot output to the recording layer of the optical disc 10, where , using the high frequency phase lead compensation filter 511 shown in FIG. 5A to obtain the focus error signal FEf by applying the high frequency phase lead compensation to the focus error signal FE, which compensation is used for zero cross judgment.

Fourth embodiment

An optical disc recording/reproducing apparatus and method as a fourth embodiment of the present invention will be explained below with reference to FIGS. 14 to 17A-17C.

The difference between the fourth embodiment and the third embodiment of the present invention is that the timing at which the first deceleration pulse DECCE1 is issued in the fourth embodiment is different from that of the third embodiment. Others are similar to the third embodiment.

In the fourth embodiment, it is necessary to determine the levels PI _L1 -PI _Ln of the summation signal RF when the beam spot is focused on each recording layer of the optical disk in advance. The levels PI _L1 -PI _Ln of the sum signal RF when the beam spot is focused on each recording layer of the optical disc are measured and stored in the optical disc.

Fig. 14 is a view schematically showing a cross-sectional structure of a multilayer optical disc used in the fourth embodiment.

Unlike the optical disc 10 shown in FIG. 5 having two recording layers, the optical disc 10A shown in FIG. 14 has three recording layers and has portions where levels PIL1-PIL3 of the summation signal RF are recorded.

The total number of recording layers of this optical disc 10A and the reflectances of the recording layers 12-14 are recorded in the read-in area RI of the first recording layer 14 of the optical disc 10A. The beam spot is first focused on the first recording layer 14, from which information is written and then recorded into a memory (not shown) within the DSP 51 . When the level PI _L1 of the summation signal RF of the first recording layer 14 is known, the second and third recording layer 13 can be calculated from the reflection levels PI _L2 -PI _L3 of the second and third recording layers 13 and 12. The level PILn of the summation signal RF in the sum 12 = PI _L1 x RLn/PI _L1 .

15A is a graph for explaining the method of calculating the levels PI _L1 -PI _L3 of the summation signal RF in the recording layers 12-14 of the optical disc 10A, wherein, after the DSP 51 is sent from the DSP 51 to the focus driver 56 with a constant The level of the summation signal RF is obtained when the gradient focus jump drive signal FJ _drv and the objective lens 34 is continuously moved in the focus direction by the coaxial actuator 35 .

As shown in FIG. 15A, if the total number of recording layers is known, it is possible to determine the summation signal in the recording layers 12-14 by making the objective lens 34 close to each recording layer of the optical disc 10A until the peak number of the summation signal RF is read. RF level.

In the initial steps t00-t01, the maximum value of the summation signal RF is smaller than the judgment level JL, so it is ignored.

After time t01, the maximum value of summation signal RF exceeds judgment level JL.

Simultaneously with detecting the sum signal of the third recording layer at time t02, DSP 51 outputs negative focus drive signal BFDRV (negative polarity focus drive signal FJ _drv ) to focus driver 56 for moving objective lens 34 away from optical disc 10A.

In the above description, the total number of recording layers and the reflectance information are recorded in the first recording layer 14 of the optical disc 10A, but they may also be recorded in the other recording layers 12 and 13 .

16 is a flowchart of focus control processing from when the control microcomputer 60 issues a focus jump command to the DSP 51 to when the focus jump is completed in the fourth embodiment of the present invention. In Fig. 16, in the same manner as Fig. 12, steps D1-D4 show that DSP 51 drives the coaxial actuator 35 and the operation of moving objective lens 34 in the focus direction through focus driver 56, and steps S11-S15 show the operation by DSP The monitoring/judging process performed by 51, and steps T1-T4 show the timer and the timing process performed by DSP 51.

In the flowchart shown in FIG. 16 , step 12A is added to the flowchart shown in FIG. 14 . The rest of the processing is the same as that explained in conjunction with FIG. 12 .

17A-17C are the focus error signal FE (FIG. 17A) obtained by dividing the current summation signal RF by the summation signal in the target recording layer to be focused on in the focus jump operation of the fourth embodiment of the present invention. Level PI _LK+1 ( FIG. 17B ), and a waveform diagram of the focus drive signal FJ _drv ( FIG. 17C ).

This exemplifies the case where the beam spot is focused on the kth layer of the optical disc 10A, and the focus of the beam spot is jumped to the (k+1)th recording layer.

In step D1, the DSP 51 as a focus drive control part sends an acceleration pulse ACCE having an amplitude A _acce and a period Δt _drv to the focus driver 56 (FIG. 17C, time d1), and then the DSP 51 detects that the sum signal RF shows the minimum value (step S12, time t12 of FIG. 17B ), then, when DSP 51 detects the summation in the target recording layer of the irradiated beam spot in the optical disc 10A by dividing the current summation signal RF shown in FIG. 17B When the level _PILK+1 of the signal RF exceeds the threshold value PIRatio (step S12A, FIG. 17B, time t12a), the DSP 51 outputs the first deceleration pulse DECCE1 to the focus driver 56 (FIG. 17C, time d2).

Unlike the focus error signal FE, the level of the summation signal RF can tolerate the influence of aberrations, so that in an optical disc whose distance between recording layers varies, when the focus jumps, the level of the summation signal RF can be used. Flat and stable focus jump operation. It should be pointed out that if it is necessary to find the level of the sum signal RF for each recording layer of the optical disc in advance, the program becomes complicated and the format of the optical disc is limited, so that when the level of the current sum signal RF reaches a certain threshold DSP 51 generates first deceleration pulse DECCE1, and DSP 51 generates first deceleration pulse DECCE1 when the level of current summation signal RF is the minimum value (FIG. 17B, time t12). At this time, the same effect as above is obtained.

Other modifications

The optical disc recording/reproducing apparatus and method of the present invention are not limited to the above embodiments.

For example, they can not only be realized by DSP 51, but also can be realized by various circuit devices or computers and software, as long as they have the processing function of DSP 51, the above uses DSP 51 as the focus jump of the embodiment of the present invention shown in Figure 4 Examples of processing components are explained.

In the above embodiment, the case where the optical disc recording/reproducing apparatus is configured the same as that shown in FIG. 4 and only the processing content of the DSP 51 is different is explained. Correspondingly, when using the above respective embodiments, the processing contents of the DSP 51 are different.

In the above embodiment, the example in which the processing requiring high-speed real-time processing is processed by the DSP 51 and the overall processing of the optical disc recording/reproducing apparatus is handled by the control microcomputer 60 is explained, but the processing contents of the control microcomputer 60 and the DSP 51 can be appropriately changed division.

Furthermore, it is also possible to realize the processing contents of the DSP 51 through hardware circuits, such as the phase compensation processing explained in conjunction with FIG. 6 .

According to the present invention, even in an optical disc recording/reproducing apparatus using a high-density writable multilayer optical disc, stable movement of a beam spot between recording layers becomes possible.

In the present invention, it is also possible to stabilize the focus pull-in operation by using a technique of outputting a value proportional to the differential of the focus error signal as a braking pulse to the focus driver.

Industrial applicability

The optical disc recording/reproducing apparatus of the present invention can be used as recording apparatuses in various industrial fields.

Claims (1)

1. optical data recording/reproducing device with focus actuator (35), this focus actuator (35) is used for carrying out with recoding/reproduction operates corresponding focus jump operation, described focus jump operation is used to make laser beam spot to move between a plurality of recording layers of the multiplayer optical disk with a plurality of recording layers, the operation of described recoding/reproduction is used at described multiplayer optical disk identifying recording layer or is used to reproduce the data of record, and described optical data recording/reproducing device comprises:

Optical pickup apparatus (30), optical pickup apparatus has object lens (34), on focus direction mobile object lens focus actuator (35), be used to launch light beam beam emissions parts (42), be used to receive the light-receiving member (32) and the optical system (33) of the light that returns from described CD, described optical system is used for the light beam from described beam emissions parts is directed to described object lens and a back light that incides on the described object lens from described CD is directed to described light-receiving member;

Focus error signal production part (51A) is based on from the signal of described light-receiving member (32) and produce focus error signal (FE);

Summing signal production part (51B) is based on from the signal of described light-receiving member (32) and produce summing signal (RF); And

Focus on drive control component (51);

Wherein said focusing drive control component (51) is carried out following action:

To described focus actuator (35) output acceleration pulse signal (ACCE), so that described object lens (34) move on focus direction, handle navigates to the target localization recording layer of described multiplayer optical disk when applying focus jump commencing signal and target localization recording layer signal with box lunch from the bundle spot of described object lens (34)

Waited for for first stand-by period,

When waiting for described first stand-by period during the currency of the current summing signal (RF) that produces from the back light of described CD express minimum value (MIN), and then value (RF/PI by described current summing signal (RF) is obtained divided by the reflectivity information by the specified recording layer of target localization recording layer signal _LK+1) when surpassing threshold value (PIRatio), export the mobile first deceleration pulse signal (DECCE1) that slows down that is used for described object lens (34) to described focus actuator (35), wherein, target localization recording layer signal record is in the recording layer of described multiplayer optical disk

Waited for for second stand-by period, and

When waiting for described second stand-by period during the absolute value representation of the described focus error signal (FE) that produces from the back light of described CD go out maximal value and when then intersecting, be used to stop second deceleration pulse (DECCE2) that moves of described object lens (34) to described focus actuator (35) output with zero.

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