JP2004178735A - Focus servo controller, method for controlling layer jump of multilayer optical disk and program for executing the method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a focus servo controller which can keep the moving speed, timing, etc., between layers always constant and can secure the stability of a layer jump, a method for controlling the layer jump of a multilayer optical disk and a program for executing the method. <P>SOLUTION: The focus servo controller has a focus error signal processing means (121) which performs normalization processing to match the focus error signal generated during a focus search to a recording surface of a selected recording layer with a preset reference value, a correction gain calculating means (122) which calculates a correction gain value in accordance with the level value of the focus error signal and the level value of the reference value and an acceleration/deceleration pulse correcting means (160) which applies the correction gain calculated by the correction gain calculating means to the acceleration/deceleration pulse used for the layer jump. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a focus servo control device, a layer jump control method for a multilayer optical disc, and a program for executing the method. More specifically, the present invention relates to the movement of a pickup focus between layers of a multilayer optical disc such as a DVD (Digital Versatile Disk). To perform an inter-layer movement (hereinafter, referred to as a layer jump) operation in order to perform the operation.
[0002]
[Prior art]
2. Description of the Related Art An optical disk reproducing device used for a conventional audio device, visual device, or computer peripheral device has a configuration as shown in FIG. The operation of the conventional optical disk reproducing apparatus shown in FIG. 6 will be described. First, an electric signal read by the optical pickup 12 from the optical disk 11 rotated by the disk motor 13 is input to the RF amplifier 15, and the RF amplifier 15 A tracking error signal (hereinafter abbreviated as a TE signal), a focus error signal (hereinafter abbreviated as an FE signal), and an RF signal used as an information signal are extracted from the above. The TE signal and the FE signal are AD-converted by the AD converter 40. The RF signal is input to the RF signal level detection circuit 31, and the output is AD-converted by the AD converter 40. The data converted to these digital values are latched by the TE register 41, the FE register 42, and the RF level register 43, respectively. Then, the data of the TE register 41 is sent to the digital tracking servo control circuit 49. The output is converted to an analog value by the DA converter 53 and sent to the actuator driver 19. On the other hand, the output of the servo control circuit 49 is also sent to a digital feed motor control circuit 51, converted to an analog value by a DA converter 52, and sent to the motor driver 18. The output of the actuator driver 19 drives a tracking actuator (not shown) of the optical pickup 12, and the output of the motor driver 18 drives the feed motor 14.
[0003]
Then, the focus error data latched by the FE register 42 is sent to the FE hold register 46 and is also sent to the selector 48 at the same time. The selector signal of the selector 48 depends on the output signal of the level comparator 47. That is, the level comparator 47 compares the absolute values of the data of the FE register 42 and the data of the FE hold register 46, and outputs “H” when the absolute value of the data of the FE hold register 46 is large, This is input to the AND gate 60 together with the output signal of the timer circuit 56. When the output signal of the timer circuit 56 is “H”, the input terminal S of the selector 48 becomes “H”, and the data of the FE hold register 46 is output from the selector 48. When the absolute value of the data in the FE hold register 46 is equal to or smaller than the absolute value of the data in the FE register 42, the level comparator 47 outputs “L”. In this case, the output of the AND gate 60 becomes "L", and the selector 48 outputs the data of the FE register 42. The timer circuit 56 starts when the lens makes a layer jump and reaches the target layer, and the servo mechanism operates again. Then, "H" is output for a certain period of time.
[0004]
Next, a digital value corresponding to a predetermined level is set in the RF reference register 44. The level comparator 45 compares the output of the RF reference register 44 with the output of the RF level register 43 and selects whether to hold the FE hold register 46 or to output the result of the FE register 42 as it is. That is, when the value of the RF level register 43 falls below the value of the RF reference register 44, the value of the FE register 42 is held by the FE hold register 46. The output of the selector 48 is sent to a digital focus servo equalizer 50, the output of which is added to the output signal of a lens drive signal generation circuit 55 prepared for performing a layer jump, and converted to an analog value by a DA converter 54. You. The RF signal is also sent to a data extracting circuit & CD / DVD data signal processing circuit 26, where the RF signal is binarized by the data extracting circuit, a bit clock and a synchronizing signal are extracted, demodulated, and corrected using the correction RAM 27. Is made. This synchronization signal is sent to the disk motor control circuit 24 to control the disk motor 13 through the disk motor driver 25.
[0005]
In the case of a DVD movie, the data corrected by the data extraction circuit & CD / DVD data signal processing circuit 26 is sent to an MPEG video decoder & audio decoder processing circuit or a data buffer circuit 28, and then a video signal or an audio signal. Is output. In the case of a DVD-ROM, output data from the data extraction circuit & CD / DVD data signal processing circuit 26 is sent to an MPEG video decoder & audio decoder processing circuit or a data buffer circuit 28, and the output signal is converted into digital data by the host personal computer. Etc. The system controller 29 controls the control timing of each control circuit and the operation of the entire set.
[0006]
Here, at the time of the read / write operation in the same layer, the loop gain of the focus servo is automatically adjusted as described in, for example, Patent Document 1. At the time of a layer jump, the lens (optical system) is moved to a target layer according to the acceleration pulse and the deceleration pulse generated by the lens drive signal generation circuit 55. At this time, the timing of the acceleration pulse and the deceleration pulse is controlled while monitoring the FE signal output from the digital focus servo equalizer 50.
[0007]
[Patent Document 1]
JP-A-10-143873
[0008]
[Problems to be solved by the invention]
However, the above prior art has the following problems. The acceleration and deceleration pulses have a fixed amplitude. This fixed amplitude value is determined at the time of design. However, in practice, deviations in the inter-layer moving speed, the output timing of the deceleration pulse, and the like occur due to fluctuations in the servo driver gain, the sensitivity of the pickup actuator, and fluctuations over time. Since the acceleration pulse and the deceleration pulse having a fixed amplitude value are used for such a shift, the stability of the layer jump is adversely affected. If the layer jump fails when the focus servo is turned on again and the beam spot moves away from the destination layer, the servo must be returned to the initial state and the focus search must be performed again, so time is spent on recovery. Would.
[0009]
Accordingly, the present invention solves the above-mentioned problems of the prior art, and corrects acceleration and deceleration pulses during layer jump even when fluctuations in gain and sensitivity of a driver or an actuator occur, thereby moving speed and timing between layers. It is an object of the present invention to provide a focus servo control device, a layer jump control method for a multilayer optical disc, and a program for executing the method, which can always keep the constant value and can ensure the stability of the layer jump.
[0010]
[Means for Solving the Problems]
In order to solve the above problem, a focus servo control device according to the present invention is provided with a normal servo that adjusts a level value of a focus error signal generated during a focus search on a recording surface of a selected recording layer to a preset reference value. Error signal processing means for performing a conversion process, correction gain calculation means for calculating a correction gain value based on a level value of a focus error signal and a level value of a reference value, and an acceleration pulse and a deceleration pulse used for a layer jump. And acceleration / deceleration pulse correction means for applying the correction gain calculated by the correction gain calculation means. Since the correction gain value is calculated by performing the normalization process and the acceleration / deceleration pulse is corrected using the calculated value (for example, the intensity is corrected), the moving speed and timing between the layers are always kept constant. Therefore, the stability of the layer jump can be secured.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
[0012]
FIG. 1 is a block diagram showing a configuration of a focus servo control device according to an embodiment of the present invention. In the figure, a focus servo control device according to the present embodiment includes: an optical pickup 100 having an objective lens 101 and a focus actuator 102; a servo control unit 120 having an RF amplifier 110; a focus error amplifier 121; and a loop gain adjustment amplifier 122; It includes switches 130 and 140, a focus search signal generator 150, a pulse correction amplifier 160, a layer jump pulse generator 170, a driver 180, and a controller 190. In FIG. 1, an optical disc device is configured to include a circuit for processing a TE signal and an RF signal (for example, the RF signal level detection circuit 31 and the data signal processing circuit 26 shown in FIG. 6).
[0013]
A focus error amplifier 121 in the servo control unit 120 performs a focus error for performing a normalization process for adjusting a level value of a focus error signal generated during a focus search on a recording surface of a selected recording layer to a preset reference value. Functions as signal processing means. Further, the loop gain adjustment unit 122 functions as a correction gain calculation unit that calculates a correction gain value based on the level value of the focus error signal and the level value of the reference value. Further, the pulse correction unit 160 functions as an acceleration / deceleration pulse correction unit that applies the correction gain calculated by the correction gain calculation unit 122 to the acceleration pulse and the deceleration pulse used for the layer jump.
[0014]
The operation of the focus servo control device according to the present embodiment having such a configuration will be described below with reference to FIG. 2 showing signal waveforms of a focus search signal (hereinafter abbreviated as FS signal) and an FE signal at the start of disk reproduction. When a focus search is performed at the start of disc reproduction, the changeover switch 130 has been switched to the focus search signal generator 150 side, and the changeover switch 140 has been switched to the changeover switch 130 side. In such a switching state, the focus search signal (hereinafter abbreviated as FS signal) generated by the focus search signal generator 150 is supplied to the driver 180 via the changeover switch 130 and the changeover switch 140, and the objective of the optical pickup 100 is When the lens 101 is moved up and down with respect to the disk surface, as shown in FIG. 2, an S-curve amplitude occurs in the FE signal in the recording layer. Then, as shown in FIG. 2, the servo control unit 120 adjusts the gain of the focus error amplifier 121 in the servo control unit 120 so that the amplitude of the S curve of the FE signal becomes a predetermined level.
[0015]
Next, the changeover switch 130 is switched to the loop gain adjustment amplifier 122 side of the servo control unit 120 to close the servo loop and adjust the loop gain. Here, the loop gain automatically adjusted by the loop gain adjustment unit 122 is set in the pulse correction amplifier 160. At the time of the layer jump operation, the changeover switch 140 is switched to the pulse correction amplifier 160 side, and the acceleration pulse and the deceleration pulse are corrected from the layer jump pulse generator 170 and supplied to the driver 180 so that the objective lens 101 of the optical pickup 100 is moved. The jump operation is performed on the layer on the disk surface.
[0016]
FIG. 3 is a flowchart illustrating a focus error signal normalizing operation of the focus servo control device according to the present embodiment. As described above, the layer jump control method for a multilayer disc according to the present invention performs the intensity correction of the acceleration pulse and the deceleration pulse in the layer jump operation to perform a more stable layer jump operation. Performs focus error signal normalization operation. First, a focus search (no focus pull-in) is performed (step S101), and a focus error amplitude level during the search is captured (step S102). A correction gain (G _FE ) (= FEp-p / FEref) is calculated from the obtained signal level and reference level (step S103). Then, the correction of the correction gain (G _FE ) is applied to the focus error of the input stage (step S104). A focus search (with focus pull-in) is performed (step S105), and a focus pull-in is performed (step S106). Finally, the loop gain is adjusted. That is, the adjustment value _GACT is stored (step S107). In this manner, normalization is performed so that the focus error obtained during focusing is adjusted to the reference value, and processing for constantly keeping the focus error input to the servo DSP is performed. It should be noted that such normalization processing of the focus error signal is performed when the power of the device is turned on.
[0017]
Next, in a layer jump operation performed when actually reproducing a multi-layer disc such as a DVD disc, as shown in FIG. 4, which is a layer jump operation flow, first, the tracking servo is turned off (step S201), and the reference layer jump is performed. The actuator is driven with a correction pulse obtained by multiplying the focus actuator drive pulse PULSE _REF by the adjustment value G _ACT to perform a layer jump operation (step S202).
[0018]
Here, FIG. 5A shows signal waveforms of the FE signal and the focus drive signal (acceleration pulse and deceleration pulse) at the time of the layer jump operation from the first layer to the second layer, and FIG. Shows the signal waveforms of the FE signal and the focus drive signal (acceleration pulse and deceleration pulse) in the layer jump operation from the second layer to the first layer. The amplitudes PH and PL of the focus drive signal are corrected with the adjustment value _GACT . This correction is performed by the pulse correction amplifier 160 (PULSE _ACT = G _ACT × PULSE _REF ).
[0019]
Thereafter, the tracking servo is pulled in (step S203). That is, the focus servo loop is closed, and the loop gain is adjusted to obtain the correction gain _GFE with respect to the ideal value. The obtained correction gain _GFE is equivalent to the gain fluctuation amount of the servo driver and the sensitivity fluctuation of the focus actuator because the focus error has already been normalized as described above. Utilizing the above, the acceleration pulse and the deceleration pulse used for the layer jump are corrected with the correction gain _GFE to determine the pulse intensity actually output to the focus actuator.
[0020]
As described above, the correction processing of the acceleration pulse and the deceleration pulse is performed, and the inter-layer moving speed, the timing, and the like can be always kept constant, and the operation can be stabilized.
[0021]
The embodiment of the present invention has been described above. The present invention is not limited to the above embodiments, and various modifications can be made within the scope of the present invention.
[0022]
【The invention's effect】
According to the present invention described above, the acceleration and deceleration pulses are corrected at the time of layer jump, and the movement speed and timing between layers are always kept constant even when the gain or sensitivity of the driver or actuator fluctuates. And the stability of the layer jump can be ensured.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a focus servo control device according to an embodiment of the present invention.
FIG. 2 is a timing chart showing signal waveforms of an FS signal and an FE signal at the start of disk reproduction.
FIG. 3 is a flowchart showing a focus error signal normalizing operation of the focus servo control device according to the present embodiment.
FIG. 4 is a flowchart showing a layer jump operation.
FIG. 5 is a timing chart showing signal waveforms of an FE signal and a focus drive signal during a layer jump operation.
FIG. 6 is a block diagram showing a configuration of a conventional optical disc reproducing device.
[Explanation of symbols]
11 Disk 12 Optical Pickup 13 Disk Motor 14 Feed Motor 15 RF Amplifier 18 Motor Driver 19 Actuator Driver 24 Disk Motor Control Circuit 25 Disk Motor Driver 26 Data Extraction Circuit & CD / DVD Data Signal Processing Circuit 27 Correction RAM
28 MPEG video decoder & audio decoder processing circuit or data buffer circuit 29 System control 31 RF signal level detection circuit 40 AD converter 41 TE register 42 FE register 43 RF level register 44 RF reference register 46 FE hold register 47 Level comparator 48 selector 49 Digital tracking servo control circuit 50 Digital focus servo equalizer 51 Digital feed motor control circuit 52 D / A converter 53 D / A converter 54 D / A converter 55 Lens drive signal generation circuit 56 Timer circuit 60 AND gate 100 Optical pickup 101 Objective lens 102 Focus actuator 110 RF amplifier 120 Servo control unit 121 Focus error amplifier 122 Loop gain adjustment amplifier 130 140 changeover switch 150 focus search signal generating unit 160 pulse correction amplifier 170 layer jump pulse generator 180 driver 190 control unit

Claims (5)

A data beam is selectively irradiated on a multilayer optical disc having data recorded on a plurality of recording surfaces, and is read out from reflected light of a recording surface of a recording layer selected from a plurality of recording surfaces of the multilayer optical disc. The focus position of the light beam on the recording surface of the selected recording layer on the basis of the detected signal, the level value of the focus error signal generated during the focus search on the recording surface of the selected recording layer Focus error signal processing means for performing normalization processing to match a preset reference value, correction gain calculation means for calculating a correction gain value based on the level value of the focus error signal and the level value of the reference value, Acceleration / deceleration for applying the correction gain calculated by the correction gain calculation means to the acceleration pulse and the deceleration pulse used for the layer jump Focus servo control apparatus characterized by having a pulse correction unit. An optical disc device having the focus servo control device according to claim 1. A data beam is selectively irradiated on a multilayer optical disc having data recorded on a plurality of recording surfaces, and is read out from reflected light of a recording surface of a recording layer selected from a plurality of recording surfaces of the multilayer optical disc. A focus error signal generated during a focus search on a recording surface of a selected recording layer in a layer jump control method for moving a focal position of a light beam to a selected recording layer based on the detected signal. A correction gain value is calculated based on the focus error signal level and the level value of the reference value by performing normalization processing according to the value, and the acceleration pulse and the deceleration pulse used for the layer jump are corrected based on the calculated correction gain value. A layer jump control method for a multilayer optical disc, characterized in that: The method according to claim 3, wherein the correction gain value is calculated by dividing the focus error signal level by a level value of a reference value. The computer performs a normalization process to match a focus error signal generated during a focus search to the recording surface of the selected recording layer with a preset reference value, and converts the focus error signal level and a reference value level value to the above. A layer jump control program for a multilayer optical disc for executing a procedure for calculating a correction gain value based on the calculated correction gain value and a procedure for correcting an acceleration and deceleration pulse used for a layer jump based on the calculated correction gain value.

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