JP2004206872A - Optical disk reproducing device, and method for optimizing servo control for optical disk reproducing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the waiting time at the start of an optical disk reproducing unit even for a disk having a plurality of recording layers for promptly accurately obtaining the optimum state of servo control for the optical disk reproducing device and to cope with sudden temperature changes or the like without interrupting the reproduction in a normal reproduction mode. <P>SOLUTION: In a method for optimizing the servo control for the optical disk reproducing device, the control in a servo control means is readjusted to be optimized in each layer, firstly optimization is applied to the layer conducting the reproduction instead of applying the optimization to all the layers when starting the device, and after once storing the reproduction data on a memory, the optimization is applied to the other layers when reading the data for reproduction, namely, when an optical head is in a stand-by mode. The optimization is performed by measuring the frequency response or jitter of a reproduction signal, and optimizing the gain of a transversal filter passing through the reproduction signal. In addition, the physical state of the optical disk reproducing device, itself, or an optical disk is detected. When the optimization is required, the optimization is applied to each layer in the stand-by state. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to an optical disk recording / reproducing apparatus or an optical disk reproducing apparatus for recording / reproducing a signal on / from a disk-shaped recording medium, and more particularly, to appropriately controlling a servo control mechanism of a recording / reproducing head and reproducing from an optical pickup. Regarding signal optimization, specifically, data is recorded in a predetermined block time unit on a disk such as a DVD (digital video disk or digital versatile disk) on which data can be recorded on a plurality of recording layers. And optimization control of an information recording / reproducing apparatus to be reproduced.

  Generally, in this type of information recording / reproducing apparatus, tracking control and focus control of an optical head are performed, and data is accurately written and read during recording and reproduction. Such control is performed by controlling the optical head by a so-called servo control circuit. As a method of generating a tracking error signal used for tracking control of an optical head, a three-beam method and a phase difference method (phase difference detection method: DPD method) are generally used. These methods are described in, for example, "Compact Disc Reader", pp134-138 (Showa 57), published by Ohmsha, and Japanese Patent Application Laid-Open No. 61-230637. Various types of disc-shaped optical recording media have been developed. As discs having a diameter of 12 cm, in addition to a so-called CD (compact disc), a plurality of discs such as a CD-ROM, a video CD, and a DVD (digital versatile disc) have been developed. The types have been put to practical use.

  Among these optical recording media, DVD has a high signal recording density. Of the EFM + reproduction signals obtained by reading the DVD recording signal with the optical head, the reproduction amplitude of the 3T wavelength signal is about 25% of the reproduction amplitude of the 14T wavelength signal among the 3T to 14T wavelength signals. become. Therefore, the frequency characteristics of the high-frequency signal are raised by a waveform equivalent equalizer to improve the signal jitter.

  However, the shape of the pits of the disk, the optical frequency characteristics of the optical pickup, and the frequency characteristics of the IV conversion amplifier, the operational amplifier, and the like change from the initial time due to the effects of temperature change and aging. Therefore, among the plurality of manufactured optical disk reproducing devices, there may be a case where the state of each part varies. If you try to re-adjust the offset, balance, gain, etc. of the tracking error signal and focus error signal in response to the physical change of the usage environment of the optical disk recording / reproducing device or the optical disk reproducing device or the non-uniformity of the disk, In the method of (1), the optical disk recording / reproducing apparatus or optical disk reproducing apparatus must be stopped once and released from the recording or reproducing state. Therefore, the use environment of the optical disk recording / reproducing apparatus or optical disk reproducing apparatus suddenly changes during recording or reproducing. However, it was not possible to respond to such a case. For example, when the outside temperature is −30 ° C., and a disc placed in such an atmosphere is brought indoors at + 25 ° C. and loaded into an optical disc recording / reproducing apparatus or an optical disc reproducing apparatus, automatic recording or reproduction is started at the beginning. The offset, balance, and gain of the tracking error signal and the focus error signal set appropriately and appropriately change over time, and servo control becomes impossible at a certain time, that is, at a time when the disk temperature has risen to some extent. Sometimes.

  Prior to the present invention, the inventor of the present invention has considered the above-mentioned conventional problems, and even if there is a change in the physical state of the optical disk recording / reproducing device or the optical disk reproducing device itself or the non-uniformity of the optical recording medium, the optical disk recording / reproducing device is not used. An optical disk recording / reproducing apparatus capable of quickly and accurately re-adjusting the offset, balance, and gain of a tracking error signal and a focus error signal without stopping the reproducing apparatus or the optical disk reproducing apparatus itself, that is, without interrupting recording and reproduction. A playback device has been developed and a patent application has been filed (Japanese Patent Application No. Hei 7-31514). In one aspect of the invention disclosed in the prior application, in order to solve the above-mentioned conventional problem, the physical state of the optical disk recording / reproducing apparatus itself or the optical recording medium is detected, and the detected physical state is used as a reference value or a reference value. The optical head is compared with a temporally previous value of the physical state, and detects whether the optical head is recording or reading data on or from the optical disk or is in a standby state, and offsets and balances the tracking error signal and the focus error signal. When it is necessary to readjust at least one of the gains, the optical head is readjusted to optimize the control by the servo control means when the optical head is in a standby state with respect to the optical disk.

  In another aspect of the invention disclosed in the prior application, in order to solve the above-mentioned conventional problem, an elapsed time after the optical disk recording / reproducing apparatus itself is powered on is measured, and the measured elapsed time is measured. By comparing with the reference value, it is detected whether the optical head is recording or reading to the optical disk or in a standby state, and at least one of offset, balance, and gain of the tracking error signal and the focus error signal is readjusted. When necessary, when the optical head is in the standby state, readjustment is performed so as to optimize the control by the servo control means.

  In still another aspect of the invention disclosed in the prior application, in order to solve the above-mentioned conventional problem, an error signal generated in an error correction means of an optical disk reproducing device is counted, and the number of the counted error signals is set to a reference value. The optical head detects whether the optical head is reading data from the optical disk or is in a standby state. When the number of error signals counted exceeds a reference value, the offset, balance, and error of the tracking error signal and the focus error signal are detected. It is determined that readjustment is necessary for at least one of the gains, and when the optical head is in a standby state, readjustment is performed so as to optimize the control by the servo control means. The “optical disk recording / reproducing device” means a disk device having one or both of an optical disk recording function and an optical disk reproducing function.

  According to the invention disclosed in the prior application, when the disk has one recording layer, servo control optimization processing is performed as necessary. However, as in the case of a DVD or the like, the recording layer has two or more recording layers. If provided, focus control must be performed for each layer, and if the recording density of data differs for each recording layer, the track pitch and reflectivity will differ, and optimization processing in tracking control and focus control will also be performed. It must be performed for each layer. As described above, it is necessary to select a pickup or a signal processing circuit portion suitable for each layer and perform an optimization process due to the difference in the recording mode of each layer, and the adjustment time required for that is 1 second per layer. Then, 2 seconds for 2 layers and n seconds for n layers. For example, when this adjustment is performed for all layers after the apparatus is started or after the disc is exchanged or loaded, the playback apparatus must wait for the time to start playback. It will not be. When the optimization processing is required due to factors such as temperature change, for example, if the optimization processing is performed on both the first layer and the second layer during the reproduction of the first layer, the reproduction of the first layer is interrupted. May occur, which is inconvenient.

  Therefore, according to the present invention, even when a plurality of recording layers are provided on a disc, a desired optimization process can be performed by shortening the waiting time at the time of startup (including when the disc is replaced or loaded). A first object is to provide an optical disk reproducing apparatus and a method for optimizing servo control of the optical disk reproducing apparatus. Further, even when a disc is provided with a plurality of recording layers, when optimization processing is required due to factors such as temperature changes during normal reproduction, it is desirable that the interruption does not occur during reproduction. It is a second object of the present invention to provide an optical disk reproducing apparatus capable of performing the above optimization processing and a method for optimizing servo control of the optical disk reproducing apparatus.

In order to achieve the above object, the method comprises the following 1) and 2).
1) An optical disk reproducing apparatus for reproducing information recorded on a plurality of recording layers including a first layer and a second layer of a disk-shaped optical recording medium, wherein the memory means temporarily stores reproduction data; A time axis changing unit for reading data from the memory unit at a speed lower than a writing speed of the read data from the optical head to the memory unit when reading from the optical disk; tracking control of the optical head and / or focusing of the optical head; Servo control means for performing control, and means for setting the optical head to a standby state when the optical head is not performing a read operation on the optical disc,
Optimizing means capable of optimizing control in the servo control means for each of the plurality of recording layers,
Recording layer determining means for determining which of the plurality of recording layers information reproduction is required from,
When reproduction of information is requested for the first layer, an optimization process is performed by the optimization means on the first layer, a predetermined amount of information is read from the first layer, and stored in the memory means. When information of a first predetermined amount or more is stored in the memory means, the optical head is set to the standby state, information is read out from the memory means to perform a reproducing operation, and the optical information is read out of the second layer. When the amount of information stored in the memory unit is smaller than a second predetermined amount, a predetermined amount of information is read from the first layer to perform the optimization process by the optimizing unit. When the reproduction of information is requested for the second layer, an optimization process is performed on the second layer by the optimization means, and a predetermined amount of information is read from the second layer. When the information is stored in the memory means and the memory means stores a first predetermined amount or more of information, the optical head is set to the standby state, the information is read out from the memory means, and a reproducing operation is performed. Controlling the optimization processing by the optimization means for the recording layers other than the second layer, and when the amount of information stored in the memory means is smaller than a second predetermined amount, Control means for controlling at least after starting the optical disc reproducing apparatus or after loading the optical recording medium, so that a predetermined amount of information is read and stored in the memory means,
And the optimization means is:
Signal quality detection means for detecting the quality of a reproduction signal that is an output signal from the optical head,
Means for optimizing the quality of the output signal of the optical head according to the signal quality detected by the signal quality detection means,
An optical disc reproducing apparatus, comprising:

2) An optical disc reproducing apparatus for reproducing information recorded on a plurality of recording layers including a first layer and a second layer of a disc-shaped optical recording medium, wherein the memory means temporarily stores reproduced data; A time axis changing unit for reading data from the memory unit at a speed lower than a writing speed of the read data from the optical head to the memory unit when reading from the optical disk; tracking control of the optical head and / or focusing of the optical head; A servo control means for controlling, and a method for optimizing the servo control of an optical disc reproducing apparatus having means for setting the optical head to a standby state when the optical head is not performing a read operation on the optical disc, comprising: After starting the optical disc reproducing apparatus or after loading the optical recording medium,
Determining from which of the plurality of recording layers information reproduction is required,
Performing a servo control optimization process on the first layer when information reproduction is required for the first layer;
Reading a predetermined amount of information from the first layer and storing it in the memory means;
When information equal to or more than a first predetermined amount is stored in the memory means, the optical head is set to the standby state, information is read out from the memory means to perform a reproducing operation, and the optimization is performed for the second layer. Performing an operation;
Reading the information from the first layer and storing it in the memory when the amount of information stored in the memory is less than a second predetermined amount;
Performing the optimization process on the second layer when information reproduction is required for the second layer;
Reading a predetermined amount of information from the second layer and storing it in the memory means;
When information of a first predetermined amount or more is stored in the memory means, the optical head is set to the standby state, information is read out from the memory means to perform a reproducing operation, and a recording layer other than the second layer is recorded. Performing the optimization process for
When the amount of information stored in the memory means is smaller than a second predetermined amount, reading out a predetermined amount of information from the second layer and storing the information in the memory means;
And performing the optimization process,
Performing focus servo control on the optical head;
Performing tracking servo control on the optical head;
Optimizing the quality of the playback signal;
Obtaining the amplitude of the reproduction signal;
A filtering step of extracting a highest frequency band of the reproduction signal,
Obtaining the amplitude of the output signal of the highest frequency band extracted in the filtering step,
Storing each of the obtained amplitudes;
A calculating step of calculating to compare the stored amplitudes;
Generating a control signal that changes the frequency characteristic of the frequency characteristic changing unit according to the operation result obtained in the operation step,
Method for optimizing servo control of an optical disk reproducing apparatus having the same.

  As described above, in one embodiment of the present invention, optimization processing is not performed on all layers at least after the optical disk reproducing apparatus is started or after the optical recording medium is loaded, but optimization processing is first performed on the layer to be reproduced. After storing the reproduced data in the memory means once, reading out the read data and performing the reproducing process while optimizing the servo control for other layers, that is, by adjusting the tap gain of the transversal filter through which the reproduced signal passes. Since the frequency characteristics of the reproduction signal are optimally controlled, the waiting time at the time of starting (including the time of replacing / loading a disk) can be reduced. Also, the physical state of the optical disk reproducing apparatus itself or the optical recording medium is detected, and the control by the servo control means is optimized according to the detected physical state when the optical head is in a standby state in which the optical disk is not reading data from the optical disk. In the aspect of re-adjusting to be optimized, even if a sudden change in the physical state occurs during playback, optimization can be performed without interrupting recording and playback of audio, images, etc., and thus stable afterwards Playback can be continued.

  In addition, the elapsed time after the power is turned on to the optical disk reproducing device itself is measured, and the control by the servo control means is optimized according to the measured elapsed time when the optical head is in a standby state with respect to the optical disk. In the aspect of re-adjusting, even if a sudden change in the physical state occurs during playback, optimization can be performed without interrupting playback of audio, images, etc., and thereafter stable playback can be performed. Can continue.

  Further, the error signal generated by the error correction means is counted, and readjustment is performed according to the counted number of the error signals so as to optimize the control by the servo control means when the optical head is in a standby state with respect to the optical disk. In this mode, even if a sudden change in the physical state or other undesired phenomena occurs during playback, optimization can be performed without interrupting recording and playback of audio and images, and thus stable afterwards. Playback can be continued.

  Hereinafter, embodiments of the present invention will be described together with preferred examples with reference to the drawings. FIG. 2 is a block diagram showing a DVD recording / reproducing apparatus as an embodiment of the optical disc reproducing apparatus according to the present invention. FIG. 1 is a flowchart showing a processing procedure of a part related to optimization processing at the time of startup (including the time of disk replacement / loading) during operation of the microcomputer (microcomputer) 11 in FIG. FIG. 3 is a flowchart showing a processing procedure of a part related to the optimization processing at the time of normal reproduction. Note that the same step numbers in FIG. 1 and FIG. 3 indicate substantially the same processing. On the other hand, the same step numbers in FIGS. 9 and 12 to 14 indicate substantially the same processing, but have no relevance to the step numbers in FIGS. 1, 3 and 18.

  Discs known as DVDs (digital video discs) include a pit-type disc dedicated to reproduction, like a conventional audio disc in which only audio is recorded, a phase-change type optical disc capable of recording and reproduction, and a disc once. There is a so-called write-once type disc that can only be written. In the present embodiment, a description will be given by taking as an example a recordable and reproducible disc having a laminated structure of two recording layers. That is, in FIG. 2, the disk 1 has a track formed in a spiral form from the inner circumference to the outer circumference, and the optical pickup 2 gives a laser beam spot to this track to obtain bibliographic information of a predetermined format, Audio information and video information are optically recorded and reproduced. The disk 1 is servo-controlled by the servo circuit of the block 10 based on the signal read and reproduced by the optical pickup (optical head) 2, and the spindle motor 3 and the motor driver / tracking / focus control circuit 4 perform CLV (CLV) control. It is rotated at a constant linear velocity. The optical pickup 2 has a superimposer 5. The optical head 2 can be moved in the radial direction of the disk 1 by the traverse motor 6.

  The optical pickup 2 also has a laser diode that emits a laser beam to the disk 1. A signal obtained by reproducing optical information recorded on the disk 1 on the basis of the reflected light, and four types of focus using the astigmatism method. It outputs error signal detection signals A to D and two types of tracking error signal detection signals E and F of a three-beam method (see FIG. 7 described later). These signals A to F are amplified by the head amplifier 8 whose frequency characteristics are switched in accordance with the frequency, and output to the preamplifier 9 which operates as a detecting / adjusting means. Further, a signal for driving a laser diode in the optical pickup 2 is applied from the preamplifier 9 to the head amplifier 8.

  A temperature sensor 20 for measuring an ambient temperature is provided near the optical pickup 2 and near the disk 1. The output signal is input to the A / D converter 11a of the microcomputer 11. The preamplifier 9 outputs a reproduced EFM signal, a focus error signal FEO, a tracking error signal TEO, and the like to the variable speed transfer controller / memory controller / EFM modulation / demodulation / error correction / servo circuit block 10. The servo circuit of the block 10 is constituted by, for example, a DSP (Digital Signal Processor). The 4 MB DRAM 13 temporarily stores data when compressing and decompressing data at the time of recording and reproduction. Writing and reading are controlled by the memory controller of the block 10 which receives an instruction from the microcomputer 11. .

  The variable speed transfer controller / memory controller / EFM modulation / demodulation / error correction / servo circuit block 10 encodes the recording data and modulates it into an EFM signal at the time of recording, transfers the data at a variable speed, and transmits the data through the preamplifier 9 to the head amplifier 8. Output to Also, at the time of reproduction, the block 10 demodulates the EFM signal from the preamplifier 9, performs error correction decoding, and transfers data at a variable speed. The servo circuit of the block 10 controls the optical pickup 2 via the motor driver / tracking / focus control circuit 4 so that the optical pickup 2 performs tracking and focusing on the track of the disk 1 based on the focus error signal FEO and the tracking error signal TEO. . Further, at the time of writing, the microcomputer 11 moves the optical pickup 2 to the vicinity of the innermost circumference (TOC: Table Of Contents) of the disk 1 and reads necessary ID information, and determines the offset and balance of the tracking error signal TEO as described later. adjust. The compression / expansion control means 14 compresses (encodes) the recording signal by a predetermined method and decompresses (decodes) the reproduced signal by a predetermined method. Note that an A / D converter and a D / A converter can be provided as needed in the interface between the block 10 and the outside for video signals, audio signals, and ROM signals.

  The microcomputer 11 drives an A / D converter 11a that receives various signals A to F, FEO, TEO, and the like from the preamplifier 9 and a laser diode LD in the optical pickup 2 with a signal corresponding to, for example, a 12-bit PWM signal. It has a PWM unit 11b for controlling the output power of the laser diode LD, a RAM 11c for a work area, a ROM 11d for a program, etc., and a CPU 11e for performing control as described below. These circuits 11a to 11e Are connected via a bus 11f. The RAM 11c has an area for storing the upper and lower peak values of the tracking error signal and the like for the CPU 11e to perform the adjustment described later. The PWM signal from the PWM unit 11b is converted into a DC voltage by a low-pass filter (LPF) 12, applied to a laser power control circuit (not shown), and then a laser diode in the optical pickup 2 is driven via a head amplifier 8. . The input means 16 and the display means 18 are connected to the microcomputer 11, respectively, and receive instructions from the user and display a recording / reproducing state, a control state, and the like.

  According to the present invention, as shown in the flow chart of FIG. 1, when the servo control means composed of the blocks 4, 10 and the preamplifier 9 needs to be optimized, the optimization is performed. The contents of the servo control will be described. First, the configuration of the preamplifier 9 will be described in detail with reference to FIG. RF signals A, B, C, and D input from the optical pickup 2 via the head amplifier 8 are output to the EFM modulation / demodulation / error correction circuit 10 as EFM signals via the information reproduction signal output circuit in the preamplifier 9. . In order to adjust the focus balance, an envelope signal EFMENV of the EFM signal is detected by an EFMENV detection circuit in the preamplifier 9 (see FIG. 7 described later) and output to an A / D converter 11a in the microcomputer 11.

  Further, (A + C-B-D) is calculated using the output signals A to D of the four-divided sensor for detecting the focus error (FE) signal, and a focus error (FE) signal is generated. Further, (FE) is calculated using the output signals E and F of the two-split sensors E and F (see FIG. 7) for detecting a tracking error signal from the optical pickup 2, and a tracking error (TE) signal is generated. Is done. The well-known balance, gain, and offset of these two error signals (FE, TE) are adjusted, and the adjusted focus error signal FEO and tracking error signal TEO are adjusted by the A / D converter in the servo circuit 10 and the microcomputer 11. 11a.

  The CPU 11e in the microcomputer 11 uses these input signals and the signals from the block 10 to control the focus balance signal FBAL, the focus gain signal FG, the focus offset signal FOFS, the tracking balance signal TBAL, the tracking gain signal TG, the tracking offset signal TOFS, and the like. Is generated and supplied to the preamplifier 9. The preamplifier 9 uses these signals to adjust the balance, gain, and offset of the focus error signal FE and the tracking error signal TE, and outputs the adjusted focus error signal FEO and tracking error signal TEO from the preamplifier 9. Is done.

  Returning to FIG. 1, the procedure of the optimization process at the time of startup by the microcomputer 11 will be described. The flowchart of FIG. 1 shows an example of a procedure for performing an optimization process at the time of starting the optical disc recording / reproducing apparatus of FIG. This flow is started when, for example, the apparatus is turned on and the disc 1 is loaded. First, it is determined whether or not an instruction (Y1, Y2) for requesting information reproduction of the first layer or the second layer of the disk 1 has been input from the input means 16 to the optical disk recording / reproducing apparatus (step S1). In the following description and in step S2 and subsequent steps in FIG. 1, these two layers may be simply referred to as one layer or two layers.

  If there is a reproduction request (Y1) for one layer, or if there is no reproduction request for any layer, the optimization process for one layer is immediately executed (step S2). The one-layer optimization process is executed, and the one-layer optimization request flag 1F is set to 1. The one-layer optimization request flag 1F and a two-layer optimization request flag 2F described later are both 0 when the power is turned on or when a disc is inserted, 0 when there is a request for optimization, and when the optimization process is completed. It becomes 1. The optimization process is performed by controlling the frequency characteristics of a reproduction signal generated from the output signal of the optical head 2. In addition to the control of the frequency characteristics of the reproduction signal, at least one of offset, balance, and gain in tracking control and focus control of the optical head may be adjusted. Details of the optimization processing will be described later. When there is a reproduction request (Y2) for the second layer in step S1, the processing from step S11 described below is executed.

  When step S2 of the optimization processing of the first layer is completed, the optical head 2 is moved to the inner peripheral portion of the disk, and the TOC of one layer is read (step S3). In the next step S4, it is determined whether there is a reproduction request (Y1, Y2) similar to that in step S2. When the reproduction request (Y1) for one layer is confirmed again, the process goes to step S5, where data is read from the first layer of the optical disc 1 by the optical head 2 and written to the DRAM 13 as memory means. The data written in the DRAM 13 is read at a speed lower than the speed at which the data was written, the time axis is changed, the data is decoded and sequentially time-expanded, and output is started as a reproduction signal.

  Next, it is checked whether or not data of a certain amount (for example, about 80%) which is relatively close to the capacity is accumulated in the DRAM 13 (step S6). That is, since the data in the DRAM 13 is erased when read, the remaining amount of data decreases as the read proceeds. If there is no data of a certain amount or more in the DRAM 13 which is relatively close to the capacity, the process returns to step S5. On the other hand, if there is a certain amount of data relatively close to the capacity in the DRAM 13, it is determined in step S7 whether or not the two-layer optimization request flag 2F is 1. When 2F = 0, that is, when the optimization processing has not been executed yet for the two layers, the optimization processing for the two layers is executed in step S8.

  The processing in step S8 is basically the same as step S2 except that the target recording layer is different. However, the difference is that step S2 is executed before the optical head 2 reads out a signal, whereas step S7 is executed in the middle of data reproduction of the first-layer sound and image.

  When 2F = 1 in step S7 or after the end of step S8, a one-track kick is performed in step S9, and the apparatus stands by for the next read timing. Next, a check is made to see if there is any remaining data of less than a certain amount (for example, 20% of the capacity) close to the empty state in the DRAM 13 (step S10). On the other hand, when data of a certain amount or more does not remain in the DRAM 13, that is, when the amount of remaining data is small, the process returns to step S7 and data is newly read from the disk 1. As described above, the process of optimizing the control for the second layer by the servo control means (step S8) is performed when the optical head is in a standby state where the data of the first layer is not being read (pickup) from the disk 1, that is, read first. Since the data of the first layer is expanded during time and is reproduced during the reproduction, it is not necessary to interrupt the data reading performed by the optical head 2 one after another.

  Returning to step S4, if the request for reproduction of the second layer (Y2) is confirmed, or if there is no request for reproduction of any layer, the optimization processing for the second layer (step S11) and reading of the TOC (step S12). Execute Note that, depending on the disc, the TOC may exist only in the first layer, and in this case, step 12 is omitted. In step S11, the flag 2F is set to 1. When step S12 ends, the same determination as in step S4 is performed in step S13. When the first layer reproduction request (Y1) is confirmed, the process proceeds to step S5, and the second layer reproduction request (Y2) is confirmed. If so, go to step S14. If there is no request to reproduce any layer, step S13 is repeated. Steps S14 to S19 perform the optimization processing of the first layer during reading of the information of the second layer. The contents of steps S5 to S10 are executed by replacing the layers, and the description is omitted.

  Next, the procedure of the optimization process during normal reproduction will be described with reference to FIG. The flowchart in FIG. 3 shows, as an example, a procedure for performing the optimization processing when the optical disc recording / reproducing apparatus in FIG. 2 is in the reproducing mode. This flow is for normal playback, and is described separately from the flowchart of FIG. 1 for convenience. However, the two flowcharts of FIGS. 1 and 3 are used in combination to enable both startup and normal playback. Can be optimized. It is assumed that the temperature near the optical disc 1 is detected in real time by the temperature sensor 20 shown in FIG. 2 and is sequentially written to the RAM 11c. In addition, the measured temperature is compared with a reference value, or is compared with a measured temperature temporally before. Such processing is performed under the control of the CPU 11e in the microcomputer 11, but is not particularly shown in FIG.

  When the temperature measured by the temperature sensor 20 exceeds the reference value or changes so as to have a difference equal to or more than a predetermined value from the previously measured value, the optimization request flags 1F and 2F are set to 0. In step S20, it is determined whether the recording layer requested to be reproduced is the first layer or the second layer. In the case of the first layer, the process proceeds to step S5, and steps S5 and S6 are executed as in FIG. Next, in step S21, it is determined whether or not the optimization process is necessary as a result of the measured temperature. If the optimization process is necessary, the first layer is optimized in step S22, and the flag 1F is set to 1 and the flag 2F is set to 0. If NO in step S21 or after the end of step S22, it is determined in step S7 whether 2F = 1. Since 2F = 0 after step S22, the optimization processing of the second layer is executed in step S8. If YES in step S7 or after the end of step S8, a one-track kick is performed (step S9), and it is determined again whether the reproduction request is for the first layer (step S23). If the determination is YES, the process returns to step S5 or S21 via step S10.

  If NO in step S23 or S20, that is, if the request for reproducing the second layer is confirmed, the process proceeds to step S14. The flow of step S14 and subsequent steps is a modification of the steps of step S5 and subsequent steps for the reproduction of the second layer. Only the layers are different, and the processing contents correspond. Now, assuming that a rapid temperature change occurs during the reproduction of the second layer, an optimization request is issued in step S24, the optimization process is performed on the second layer in step S25, the flag 2F is set to 1, and the flag 2F is set to 1 Since 1F is set to 0, the next time step S16 is executed, the determination becomes NO, and the optimization processing is also performed on the first layer in step S17.

  FIG. 4 is a timing chart showing one mode of the control (first embodiment of the present invention) according to the flowchart of FIG. This example shows that steps S2 to S10 in FIG. 1 and steps S5 to S8, S21 to S23, and S10 in FIG. 3 are being executed, and is shown on the left side of the portion showing the optical head state in FIG. The first layer optimization part corresponds to step S2 in FIG. 1, and the second layer optimization part shown on the right corresponds to step S8 in FIG. The first layer optimization portion shown on the right side corresponds to step S22 in FIG. 3, and the second layer optimization portion shown on the right side (right end) corresponds to step S8 in FIG. . In FIG. 4 and FIG. 5, the part of the optimization processing is indicated by hatching. In the example shown in FIG. 4, if the temperature difference exceeds 30 ° C. at time t1, it is determined that an optimization request has been issued. In the drawing, "disc reproduction" refers to reading data from the optical disc 1 (step S5 in FIG. 1, etc.), and "reproduction" in the audio / image reproduction portion indicates a sound / image whose time axis is expanded. It does not mean what is actually provided via an audio playback device and display such as an amplifier and a speaker.

  FIG. 5 is a timing chart showing another mode of the control according to the flowchart of FIG. 1 (second embodiment of the present invention). The configuration of the second embodiment of the present invention is also substantially the same as the block diagram of FIG. 2, but the temperature sensor 20 is unnecessary in the second embodiment, the third embodiment described later, and the fourth embodiment. In FIG. 5, the first layer optimization part and the second layer optimization part shown in the part indicating the state of the optical head correspond to the optimization processing steps in FIGS. 1 and 3 as in FIG. In the example shown in FIG. 5, when the error count in the error correction processing in the block 10 in FIG. 2 exceeds a predetermined value at the time t2, it is determined that an optimization request is present.

  In the figure, "disc reproduction" and "reproduction" in the audio / image reproduction portion are the same as those in FIG. In the second embodiment, the first embodiment detects the physical state of the optical disc recording / reproducing apparatus itself or the optical disc 1 which is an optical recording medium by detecting the physical state of the optical disc 1 and the first detecting means. A comparison means (microcomputer 11) that compares the physical state with a reference value or a value before the physical state with respect to time to determine whether to perform the optimization process. A counting means (microcomputer 11) for counting error signals generated in the error correcting means in the block 10; and a comparing means (microcomputer 11) for comparing the number of error signals counted by the counting means with a reference value. It is determined whether or not to perform optimization processing. Therefore, there is no need for a means for monitoring a physical condition such as a temperature sensor.

  As a counting means for counting error signals, an error counter of C1, C2 or an error counter of C1, C2, C3 (in the case of DVD-ROM or CDROM) is provided in the error correction circuit in the block 10, or It can be realized by software. When an IC provided with a counting means for counting such an error signal is used as the IC for performing the error correction processing, this can be used. The counting means counts the number of errors at regular time intervals, and the counted value is compared with a reference value by the counting means. As described above, the second embodiment differs from the first embodiment in the material for determining whether or not there is an optimization request. Further, the comparing means can be easily realized by software of the microcomputer 11.

  Further, as a third embodiment of the present invention, there is the following variation of the second embodiment. In the third embodiment, as in the second embodiment, the optimization processing of steps S8, S22, or S17, S25 in FIG. 3 is performed based on the number of errors, but the number of errors falls below a reference value in this optimization processing. In order to check whether or not this has happened, the optical head (optical pickup 2) reads again the data block for which optimization processing has been determined to be necessary. That is, by reading the same data again, the number of errors is counted again and compared with the reference value. As a result, if the number of errors is smaller than the reference value, it is determined that there is an improvement, and the optimization process is subsequently performed based on the number of errors. On the other hand, if the number of errors is not smaller than the reference value, it is determined that there is no improvement, and thereafter, the optimization process based on the number of errors is not performed. Such processing can be performed in the flowchart of FIG. 3 instead of or together with the one-track kick in steps S9 and S18. When the disk 1 has been replaced, the startup optimization process is performed according to the flow of FIG.

  If the number of errors is not less than the reference value after the optimization processing in the third embodiment, the reason why the optimization processing is not performed thereafter is as follows. That is, the case where there is no improvement in the number of errors despite the optimization processing means that the disk 1 is extremely deteriorated, the optical pickup 2 is covered with dust, or the temperature or other environmental condition is out of the use range. In such a case, the execution of the optimization process is useless, so it is preferable to send an alarm signal from the microcomputer 11 to the display unit 18 to warn the user.

  Further, as a fourth embodiment of the present invention, the determination as to whether or not there is an optimization request can be replaced with whether or not a predetermined time has elapsed. That is, since the environmental conditions of the optical disk recording / reproducing device or the optical disk reproducing device change with time, executing the optimization process at regular time intervals is one of the preferable embodiments of the present invention. In the fourth embodiment, there is no need to provide a detecting means for detecting the physical state of the optical disc recording / reproducing apparatus itself or the optical disc 1 which is an optical recording medium, a counting means for counting an error signal, and the like. Since step S6 can be realized only by configuring a timer, the cost can be minimized.

  Next, optimization processing (steps S2, S8, S11, S17, S22, S25) common to the above embodiments will be described. For example, when performing the optimization process on the first layer during the reproduction on the first layer, the optimization can be performed while the light spot by the optical pickup remains at that position, or the track is moved to a predetermined area such as the TOC area. It can also be done on the move. When performing the optimization process on the second layer during the reproduction on the first layer, the focus of the light spot by the optical pickup may be controlled to move the light spot in the direction perpendicular to the disc. Alternatively, it can be performed by moving a track to a predetermined area.

In the first embodiment, the temperature sensor is used as the first detecting means for detecting the physical state of the optical disk recording / reproducing apparatus itself or the optical recording medium. However, instead of or in addition to this, the following items are used. Measurement and detection may be performed.
(1) Humidity change (2) Power supply voltage change (3) Physical change due to impact (4) Change in resonance state caused by difference in rotation speed between inner and outer circumferences of disk (5) Eccentricity and runout of disk Changes (6) Changes in optical characteristics due to differences in position on the disc (7) Changes in the number of rotations of the spindle motor (8) Number of times the spindle motor is started (9) Number of times or distance of movement of the optical pickup by the actuator FIG. However, since the recording information is once stored in the DRAM 13 and read out and sent from the block 10 to the preamplifier 9 even during recording, the optimization of another layer is performed during writing of one layer. It is possible to execute the processing as in the case of the reproduction. Although the block diagram of FIG. 2 has both functions of recording and reproduction, it is obvious that the present invention is also applied to an apparatus having only one of them. Furthermore, in the above example, the case where the optical disc 1 has two recording layers has been described, but the present invention is applicable to a disc having a multilayer structure of three or more layers. Although the above embodiment has been described for the case of reproduction, it is possible to perform optimization processing on a recordable disc at the time of start-up as in FIG. According to the remaining data amount, a result of detecting a physical state such as a temperature, a result of measuring an elapsed time after the optical disc reproducing apparatus itself is turned on, or performing an error correction process on the reproduced data. It is determined whether or not optimization processing is necessary from the count result of the error signal generated in the error correction unit that performs the error correction. When it is determined that the optimization processing is required, the optical head is in a standby state and each recording layer, that is, The optimization process can be performed on the recording layer on which writing is currently being performed and the other recording layers in the same manner as in FIG.

  Next, a specific method of optimization in each of the above embodiments will be described. FIG. 6 is a block diagram showing a simplified configuration as a reproducing device in the optical disk recording / reproducing device of FIG. As a specific method of optimization, the optical disk reproducing apparatus shown in FIG. 6 reproduces information from a read-only CD and a DVD, and a DVD is a read-only two-layer type, a write-once type, and a recording method. The description will be made assuming that the reproduction type is included. FIG. 7 is a circuit diagram showing an optical pickup (PU) in FIG. 6 and an arithmetic unit (part of the preamplifier in FIG. 6) which responds to an output signal thereof. Two types of tracking are performed according to the discrimination result of the disc type. 5 shows an example of a circuit for selecting one of the error signals.

The reference numerals in FIG. 6 correspond to those in FIG. 2, but the block 10 in FIG. 2 is shown as a digital signal processor (DSP) / digital servo control circuit (DSV) 10, and the microcomputer 11 is shown as a system controller 11. I have. Since FIG. 6 is a simplified diagram, some elements in FIG. 2 are omitted. The system controller 11 is connected to an EEPROM (Electrically Erasable, Programmable Read Only Memory) 7 which is a nonvolatile storage means, and predetermined data is stored in this memory as described later. Hereinafter, four preferable methods as specific methods for performing optimization in each of the above embodiments of the present invention will be described.
<First method>
FIG. 7 schematically shows a part of an optical pickup 2 having four-divided optical sensor portions A, B, C, and D and optical sensor portions E and F used for a three-beam method, and a first method for performing optimization. 2 shows an arithmetic unit (a part of the preamplifier 9) that responds to an output signal from the optical sensor part in the case of (1). Symbols A to F indicate both these optical sensor parts and their output signals. An adder 20 adds and outputs the output signals of the photosensor portions A and C on the diagonal lines, and an adder 22 adds and outputs the output signals of the photosensor portions B and D on the other diagonals. Is what you do. The adders 24 and 32 both add the output signals of the adders 20 and 22, and the subtractor 30 subtracts the output signal of the adder 22 from the output signal of the adder 20. Further, the subtracter 28 subtracts the output signal of the optical sensor portion F from the output signal of the optical sensor portion E. The output signal of the adder 24 is output as it is as an RF signal, and is also supplied to an envelope detection circuit 36 as an envelope generating means. Further, the output signal of the adder 24 is supplied to a second envelope detection circuit 37 as a second envelope generating means via the HPF 34. The output signal of the first envelope detection circuit 36 is represented as ENV, and the output signal of the second envelope detection circuit 37 is represented as 3TENV. Although the first and second envelope detection circuits 36 and 37 are provided separately in the configuration of FIG. 7, a single envelope detection circuit can be switched and used.

  The output signal of the subtractor 28 is given to a known tracking servo control system and a known focus servo control system so that the output signal of the subtracter 30 is used as a signal tracking error signal TE and the output signal of the subtracter 30 is used as a focus error signal FE. The output signal of the adder 32 is output as a sum signal (sum all (SA) signal) of the four-division optical sensor portion. The sum signal SA is a main signal for reading the recorded information of the disc and a signal to be measured for disc type discrimination described later. Note that the sum signal SA can be output via an LPF (not shown) in order to remove a high-frequency component that may be included in the sum signal SA.

  The system controller 11 performs discrimination of a disc type, which will be described later, in addition to the normal system control by the operation of the CPU 11e, measures the amplitude of the signal ENV and the signal 3TENV from the preamplifier 9, and measures the amplitude of the transformer incorporated in the preamplifier 9. The tap gain of the versal filter (see FIG. 8) is adjusted and set to be optimal. Once optimally controlled, the data is stored in EEPROM 7 which is a non-volatile storage means.

  The focus search is performed by moving the objective lens, which is a part of the optical system of the optical pickup 2, along the optical path by increasing or decreasing the voltage applied to the focus coil of the optical pickup 2. FIG. 9 is a flowchart showing an operation procedure of a microcomputer for determining a disc type by focus search as a first method of the present invention, thereafter setting parameters according to the discrimination result, and controlling a frequency characteristic of a reproduction signal. . In FIG. 9, when the control is started, when the power of the reproducing apparatus is turned on, the disc is exchanged, or when data reproduction of another layer is required in the multi-layer disc, it is determined that the initial setting is necessary ( In step S1), initialization such as clearing predetermined contents of a memory and a buffer (not shown) connected to the microcomputer is performed. Next, in step S2, necessary data is read from the EEPROM 7 and transferred to the preamplifier 9 and the digital servo control circuit (DSV) 10. In step S3, a focus search is started, and in step S4, the amount of reflected light is detected. Based on this, the type of the disc is determined. Next, in step S5, parameters are set according to the determination result. Discrimination of the disc type refers to, for example, discrimination between a CD and a DVD, and the method thereof will be described later.

  In the next step S6, the focus servo control is turned on. In the following step S7, the spindle motor is started, and in step S8, the tracking servo control is turned on. In the following step S9, the rotation speed of the spindle motor is controlled to the CLV rotation speed. In step S10, the operating point of the focus servo control is changed, and an offset for obtaining the maximum level of the ENV signal is set. That is, the level of the ENV signal is maximized while adding an offset to the operating point. If the processing in step S10 is not performed, the optical frequency characteristics change, and it is difficult to perform stable control thereafter. For the adjustment or setting of the offset in the focus servo control, a known method disclosed in the prior application of the present inventors (Japanese Patent Application Laid-Open No. 7-235072) can be applied. This is the same for the other methods described later.

  In the next step S11, the average value of the ENV signal is obtained, and in step S12, the average value of the 3TENV signal is obtained. The method of calculating the average value in steps S11 and S12 is to measure each signal level a plurality of times and calculate the arithmetic average. Note that the measurement of the signal level may be performed alternately on the two signals so that the influence of a defect or the like affects equally. In the next step S13, the 3TENV signal is divided by the ENV signal to obtain its quotient X. In step S14, a filter gain is set so as to obtain a desired X stored in the ROM in advance. The gain is set by the transversal filter included in the preamplifier 9 or the DSP / DSV 10, and its configuration is five taps as shown in FIG. The delay time T of the unit delay element can be switched between 440 ns for a CD and 80 ns for a DVD. Each gain coefficient of the five taps is stored as a table in the ROM of the microcomputer in advance in accordance with the optical characteristics of the optical pickup 2 and the electric characteristics of the amplifier, etc. Table values are set. Here, when 3TENV / ENV = X does not pass through the filter of FIG. 8, for example, if the gain of G0 is 1, G1, G2, G3, and G4 are each 0, and the initial setting value is about X = 0.2, For example, G0 = 0.02, G1 = 0.2, G2 = 1, G3 = 0.2, so that X = approximately 0.4 by calculation or by a lookup table stored in the ROM. G4 = 0.02.

  Next, in step S15, the optical pickup is moved to a target track, and reproduction and the like are started. These gain values are obtained by writing in the EEPROM 7 the values obtained by the same adjustment as described above in the manufacturing process before shipment of the reproducing apparatus. When the playback device is used by the user, these gain values are read out as a center value at the time of start-up, and when the power is turned on or the disk is inserted in FIG. The operation is performed. Note that once the processing of FIG. 9 is performed, the value can be used normally. However, when the servo control is turned off again due to the influence of vibration or the like, the adjusted value need only be set, and there is no need to measure the ENV signal or the like.

  Next, the second to fourth methods of the optimization processing according to the present invention will be described. FIG. 10 is a block diagram showing an arithmetic circuit (part of the preamplifier in FIG. 2 or 6) used in the second to fourth systems. Note that the circuit of FIG. 7 can be used for generating the tracking error signal. The circuit shown in FIG. 10 utilizes the circuit shown in FIG. 4 of Japanese Patent Application Laid-Open No. 57-74837, and the same reference numerals in FIG. 7 is different from FIG. 7 in that gate circuits 66 and 70 controlled by output signals of a falling pulse generating circuit 62 and a rising pulse generating circuit 64 in response to an output signal of the adder 24 are similar to the subtractor 30. The output signal of the function subtractor 26 is gated and applied to the hold circuits 68 and 72, respectively. The output signals of the hold circuits 68 and 72 are supplied to the + and-input terminals of a subtractor 74, respectively, and the output signal of the subtractor 74 is supplied to one terminal of the switch 60. The output signal of the subtractor 28 is given to the 0 terminal of the switch 60. Selection of the 1-side terminal and the 0-side terminal of the switch 60 is controlled by a control signal CONT1.

  The output signal of the adder 24 is output as a sum signal (SA), an EFM signal or an EFM plus signal via the LPF 58 and the equalizer (EQ) 76, respectively. The equalizer 76 is provided with a control signal CONT2 for controlling its characteristics. The output signal of the adder 24 is output as a 3T signal via a series circuit of the HPF 78 and the LPF 50. The control signals CONT1 and CONT2 are respectively generated by the CPU 11e in the system controller 11.

  Therefore, when the 0 side of the switch 60 is selected by the control signal CONT1 from the CPU 11e, the tracking error signal TE of the three-beam method is output, and when the 1 side is selected, the above-mentioned Japanese Patent Application Laid-Open No. 57-74837 is used. A tracking error signal TE similar to that shown in FIG. 4 is selected. As described in the publication, the method of obtaining the tracking error signal is such that a difference between both edges (output signals of the falling pulse generating circuit 62 and the rising pulse generating circuit 64) of the sum signal (the output signal of the adder 24) is obtained. By sampling the signal (the output signal of the subtractor 26), it is equivalent to obtaining a value obtained by adding a sign according to the direction of the deviation of the beam spot from the track to the instantaneous peak-to-peak value of the difference signal. (See FIG. 5 of the publication).

FIG. 11 is a block diagram showing the internal configuration of the DSP in the DSP / DSV 10 of FIG. 6 in the second to fourth systems. A PLL circuit 52 that matches the phase of input data read by the optical pickup 2 and supplied through the preamplifier 9 in bit units and generates a clock synchronized with a reproduction signal, and a reproduction data and an output signal of the PLL circuit 52 A comparator 54 for comparing with a certain clock and an integrator 56 for integrating an output signal of the comparator 54 are provided. In the second to fourth systems, the focus servo control is turned on, the tracking servo control is turned on, and the signal is reproduced in a state where the spindle is rotated at a predetermined rotation speed so that the jitter of the reproduced signal is optimized. This is for controlling the characteristics of the equalizer 76 while measuring the jitter. If the operation of the focus system is not optimized before the jitter at the equalizer 76 is set to the best point, the optical frequency characteristics fluctuate and the equalizer control becomes meaningless. Therefore, first, the operation of the focus system is optimized. The details of the second to fourth systems will be described below.
<Second method>
FIG. 12 is a flowchart showing a control procedure of the microcomputer in the second method. The same steps as those in FIG. 9 are denoted by the same reference numerals, and a description thereof will be omitted. The second method adjusts the best point of focus and the best point of equalizer characteristics based on the measurement of jitter. Since both focus and equalizer characteristics are measured by jitter measurement, the circuit configuration is the simplest. In step S10A of FIG. 12, in order to change the operating point of the focus servo control and optimize the quality of the RF signal, the measured value of the jitter of the reproduced signal is read from the output signal of the integrator 56 of FIG. Is reset, the measurement is performed again while adding an offset to the operating point of the focus servo control, and an offset value that minimizes the jitter is set.

Next, the characteristic of the equalizer 76 is controlled. For this purpose, the measured value of the jitter is read from the output signal of the integrator 56, and the jitter optimum point is set while switching the equalizer characteristic in several steps. Assuming that the initial measurement values are G0 = 0.02, G1 = 0.2, G2 = 1, G3 = 0.2, G4 = 0.02, the high frequency range is calculated or obtained by a look-up table stored in the ROM in advance. For example, G0 = 0.03, G1 = 0.3, G2 = 1, G3 = 0.3, and G4 = 0.03 so as to further increase the amplitude of. Then, the jitter is measured again, and control is performed so that the measured value is minimized (step S11A).
<Third method>
FIG. 13 is a flowchart showing a control procedure of the CPU 11e in the third method. The same steps as those in FIG. 12 are denoted by the same reference numerals, and a description thereof will be omitted. In the third method, the best focus point is the maximum level of the EFM signal, and the best point of the equalizer characteristics is adjusted based on the measurement of the jitter. In the second method, when the initial quality of the signal is poor, it may not be possible to measure the jitter stably, but in the third method, the level measurement is performed, so that the measurement can be performed stably in a short time. is there. In step S10B of FIG. 13, in order to optimize the quality of the RF signal, the SA signal (or 3T signal) is measured, and the SA signal (or 3T signal) is measured while adding an offset to the focus servo control operating point. Alternatively, an offset value that maximizes the level of the 3T signal) is set.

Next, the characteristic of the equalizer 76 is controlled. For this purpose, the measured value of the jitter is read from the output signal of the integrator 56, and the jitter optimum point is set while switching the equalizer characteristic in several steps. Assuming that the initial measurement values are G0 = 0.02, G1 = 0.2, G2 = 1, G3 = 0.2, G4 = 0.02, the high frequency range is calculated or obtained by a look-up table previously stored in ROM. For example, G0 = 0.03, G1 = 0.3, G2 = 1, G3 = 0.3, and G4 = 0.03 so as to further increase the amplitude of. Then, the jitter is measured again, and control is performed so that the measured value is minimized (step S11A).
<Fourth method>
FIG. 14 is a flowchart showing a control procedure of the microcomputer in the fourth method. The same steps as those in FIG. 13 are denoted by the same reference numerals, and a description thereof will be omitted. In the fourth method, the best focus point is the maximum level of the EFM signal, the best point of the equalizer characteristic is adjusted by the amplitude level adjustment of 3T, and both the best focus point and the best equalizer characteristic point are determined based on the jitter measurement. One adjustment is performed. The adjustment at the maximum level point in the third method is short and stable, but is not always accurate. Therefore, in the fourth method, the coarse adjustment is performed by the level, and the fine adjustment is performed by the jitter. In step S10B of FIG. 14, the operating point of the focus servo control is determined in the same manner as in the third method. In order to optimize the quality of the RF signal, the SA signal (or 3T signal) is measured, and an offset is added to the operating point of the focus servo control. , An offset value that maximizes the level of the SA signal (or 3T signal).

  Next, in step S11B, the average value of the envelope of the SA signal, which is the entire RF (EFM +) signal, is determined, and in step S12B, the average value of the 3T signal is determined. The method of calculating the average value in steps S11B and S12B is to measure each signal level a plurality of times and calculate the arithmetic average. Note that the measurement of the signal level may be performed alternately on the two signals so that the influence of a defect or the like affects equally. The envelope itself may be used instead of calculating the average value of the envelope of the SA signal. In the next step S13B, the 3T signal is divided by the SA signal to obtain its quotient X. In step S14A, a filter gain is set so that a desired X is obtained. Here, when 3T / SA = X does not pass through the filter 25 of FIG. 8, for example, the gain of G0 is set to 1, G1, G2, G3, and G4 are each set to 0, and the initial set value is about X = 0.25. G0 = 0.02, G1 = 0.2, G2 = 1, G3 = 0.2 so that X = approximately 0.4 by calculation or by a lookup table stored in the ROM. , G4 = 0.02.

  This set value can be obtained, for example, by reading a value stored in advance in the ROM of the microcomputer in eight stages. Subsequently, in order to ensure the accuracy of the reproduction signal, the measured value of the jitter of the reproduction signal is read from the output signal of the integrator 56 in FIG. 11 and the integrator 56 is reset so that the jitter is minimized. I do. Assuming that the initial measurement values are G0 = 0.02, G1 = 0.2, G2 = 1, G3 = 0.2, G4 = 0.02, the high frequency range is calculated or obtained by a look-up table previously stored in ROM. For example, G0 = 0.03, G1 = 0.3, G2 = 1, G3 = 0.3, and G4 = 0.03 so as to further increase the amplitude of. Then, the jitter is measured again, and control is performed so that the measured value is minimized (step S14A).

  Next, the disc determination step (S4) in each of the above flowcharts will be described. Here, a bifocal type optical pickup 2 is used, that is, as shown in Japanese Patent Application Laid-Open No. 7-65407 and Japanese Patent Application Laid-Open No. 7-98431, an objective lens is provided with two converging points and disks having different thicknesses are provided. A method for discriminating the type of a disc by using one that can deal with this will be described. The optical pickup 2 reads information from two types of discs, that is, a CD having a plate thickness of t1 = 1.2 mm and a DVD having a thickness of t2 = 0.6 mm at spots of NA = 0.38 mm and NA = 0.6 mm. . The distance between the two focal points is 0.3 mm. If an image is formed simultaneously on the disk surface and the signal surface, the disk surface is affected by modulation and offset at a low frequency as an effect of the disk surface, so that the distance between the two focal points cannot be set in the same manner as the disk thickness.

  FIG. 15 is a diagram showing a state in which a laser beam is focused on the disk 1 in such a bifocal optical pickup. 1-a is a disc with t1 = 1.2 mm, 1-b is a disc with t2 = 0.6 mm, and 1-c is a condensate light on a two-layer disc with one layer of 0.6 mm (interlayer distance t3 = 40 μm). In this state, the leading upper beam is for 1.2 mm and the trailing lower beam is for 0.6 mm. In FIG. 15, α, β, γ, and δ indicate the states in which the objective lens of the optical pickup 2 has moved in the focus direction. FIG. 16 shows various signal waveforms obtained from an output signal when a focus search is performed by the optical pickup 2 corresponding to FIG. That is, the vertical axis in FIG. 16 is voltage, the horizontal axis is time, and p indicates a peak. Since the bifocal type optical pickup is constituted by a hologram lens, signals other than two spots having two focal points are detected as in JP-A-7-98431. Here, signals other than the bifocal detection signal are used. Is omitted.

  The 2-a to 2-d in FIG. 16 correspond to the disk 1-a in FIG. 15, the 2-e to 2-h correspond to the disk 1-b in FIG. 15, and the 2-i to 2-l correspond to the disk in FIG. 1-c disks are supported. The sum signal SA in FIG. 7 is 2-a, 2-e, 2-i in FIG. 16, the focus error signal FE is 2-b, 2-f, 2-j in FIG. The signals obtained as a result of comparing the signal SA with the threshold shown by the dotted line are 2-c, 2-g, and 2-k in FIG. 16, and the signal obtained by comparing the focus error signal FE with the threshold shown by the dotted line. The signals are 2-d, 2-h and 2-l in FIG.

  The focus search is performed by moving the objective lens, which is a part of the optical system of the optical pickup 2, along the optical path by increasing or decreasing the voltage applied to the focus coil of the optical pickup 2. In the waveform 2-a in FIG. 16, the left peak in the figure is obtained in the state of α of the disk 1-a in FIG. 15, and the right peak is obtained in the state of β in the same manner. Thus, the peaks in FIG. 16 correspond to α and β in FIG. 15, and the four peaks in the waveforms 2-i to 2-l correspond to α, β, γ, and δ of the disk 1-c in FIG. Yes, it is. FIG. 17 is a waveform diagram showing a focus search in a two-layer disc, in which servo control is turned on in the second layer of a 0.6 mm disc. 3-a is a voltage applied to the focus coil, and 3-b to 3-e are waveforms corresponding to, for example, 2-i to 2-l in FIG.

  FIG. 18 is a flowchart showing an operation procedure of the CPU 11e for determining the type of the disc by the focus search shown in FIGS. That is, the flowchart of FIG. 18 shows an example of a portion corresponding to steps S3 to S6 in FIGS. 9 and 12 to 14 corresponding to each method in detail. The switch 60 shown in FIG. 10 is controlled by using the disc type determination result, and one of the three-beam method and the tracking error signal of the phase difference method is selected by the microcomputer. In FIG. 18, this flow starts when the power of the reproducing apparatus is turned on, the disk is exchanged, or data reproduction of another layer is required on the multi-layer type disk. In step S1A, initialization such as clearing predetermined contents of the memory or buffer is performed, then focus search is started in step S15A, the contents of the registers storing the peak voltages V1, V2, and V3 are set to 0, and the timer is started. Let it.

  Next, in step S16, digital values obtained by A / D converting the voltage of the sum signal SA are sequentially read, sequentially stored in a predetermined A / D conversion register, and sequentially compared with the previous value. In step S17, it is determined whether or not a peak value has been detected as a result of the sequential comparison in step S16. If YES, the peak value is stored in the V1 register in step S18, and if NO, the process returns to step S16. After the end of step S17, the A / D conversion register is reset in step S19, steps S20 and S21 similar to steps S16 and S17 are executed, and the next peak value is stored in the V2 register in step S22. The / D conversion register is reset in step S23. In the next step S24, it is determined whether or not the time measured by the timer has exceeded the set value (overflow). If it has, the process proceeds to step S28, and if not, the process proceeds to step S25. Steps S25 and S26 have the same contents as steps S16 and S17, respectively, and the peak value is stored in the V3 register in step S27. In step S28, a comparison operation is performed using the peak values V1, V2, and V3 obtained so far.

  In the next step S29, it is determined whether V1 is smaller than a predetermined value Q1 or V2 is smaller than a predetermined value Q2. If YES, the process proceeds to an abnormality processing routine in step S34. These predetermined values Q1 and Q2 are values that are sufficiently smaller than the peak value obtained in the focus search on a normal disc. If “NO” in the step S29, it is determined whether or not V1 / V2> Q3 in a step S30 (Q3 is, for example, a value of about 70% of a ratio of V1 and V2 normally obtained with a disc having a thickness of 1.2 mm). Predetermined value: This value varies depending on the design of the reproducing apparatus, and the ratio between V1 and V2 may be reversed due to the relationship between the light amounts, and the same applies to other similar comparison steps.) If “YES” in the step S30, it is determined that the current disk has a thickness of 1.2 mm, predetermined parameters are set in a step S40, and then the focus servo control is turned on in a step S31. On the other hand, if “NO” in the step S30, it is determined whether or not V2 / V1> Q4 in a step S32 (Q4 is, for example, a value of about 70% of a ratio of V2 and V1 normally obtained with a disc having a thickness of 0.6 mm). Predetermined value).

  If "YES" in the step S32, it is determined that the current disk has a thickness of 0.6 mm, a predetermined parameter is set in a step S41, and a predetermined focus servo control is turned on in a step S33. On the other hand, if NO in step S32, it is determined in step S36 whether V3> V1 (when V3 is measured) and whether V3> V2. If “YES” in the step S36, predetermined parameters are set in a step S42, and then, in a step S37, the focus servo control is turned on at a point SC (see the waveform 3-e) when the signal shown by 3-C in FIG. 17 becomes a center value. And Although not shown, the operation of turning on the focus servo control in steps S31 and S33 can also detect the type of the disc during one focus search. Therefore, during the focus search, for example, the peak voltage in the waveform 2-e is detected. The focus servo control can be turned on immediately after the detection of V2, and the focus servo control can be turned on even in a focus search in the reverse direction.

  In the flowchart of FIG. 18, the peak value V4 is not used. However, if it is determined that the disc is a two-layer disc by detecting V3 and comparing it with V1 and V2, the peak value V4 is detected before V4 is detected. This is because the search time can be reduced by turning on the servo control. The setting of the predetermined parameters in the above steps S40, S41 and S42 includes the laser power of the optical head, the gain and offset of the circuit for generating the focus error signal and the tracking error signal in the preamplifier 9 in accordance with the disc type determined. Necessary parameters such as parameters such as balance, switching of equalizer characteristics described later in the preamplifier 9 or the DSP / DSV10, delay amount of a unit delay element of a transversal filter in the preamplifier 9 or the DSP / DSV10, tap gain setting, etc. Is set. Here, it is assumed that the equalizer and the transversal filter are included in any block of the preamplifier 9 or the DSP / DSV 10. Although the amplitude of the sum signal SA is measured here, the zero-cross timing of the focus error signal FE may be used when measuring the peak value, or the signals 2-b and 2- The same applies to the measurement of the voltage values (symmetrical voltage values on one side or both sides) of the S curve of f, 2-j.

6 is a flowchart showing a control procedure for realizing an optimization process at the time of startup in the optical disc reproducing device of the present invention. FIG. 1 is a block diagram showing an optical disc reproducing apparatus as an embodiment of the optical disc reproducing apparatus of the present invention. 5 is a flowchart showing a control procedure for realizing an optimization process at the time of normal reproduction in the optical disc reproducing device of the present invention. 4 is a timing chart showing one mode (first embodiment) of control according to the flowcharts of FIGS. 1 and 3. 4 is a timing chart showing another mode (second embodiment) of the control according to the flowcharts of FIGS. 1 and 3. FIG. 3 is a simplified block diagram of FIG. 2. FIG. 7 is a circuit diagram showing an optical pickup and an arithmetic unit (part of the preamplifier in FIG. 6) used in a first method of an optimization process performed in response to an output signal of the optical pickup in the embodiment of the optical disc reproducing apparatus of the present invention. FIG. 7 is a block diagram illustrating a configuration of a transversal filter included in the preamplifier or the DSP / DSV in FIG. 6. 7 is a flowchart showing a first method of optimization processing in a processing procedure of an operation of a microcomputer used in the system controller in FIG. 6. FIG. 7 is a circuit diagram showing an optical pickup of the optical disk reproducing apparatus according to the present invention and an arithmetic unit (a part of the preamplifier in FIG. 6) used in second to fourth systems of an optimization process performed in response to an output signal thereof. FIG. 9 is a circuit diagram showing a jitter measuring circuit used in second to fourth systems of the optimization processing in the optical disc reproducing apparatus of the present invention. 7 is a flowchart illustrating a second method of optimization processing in the processing procedure of the operation of the microcomputer used in the system controller in FIG. 6. 7 is a flowchart illustrating a third method of optimization processing in the processing procedure of the operation of the microcomputer used in the system controller in FIG. 6. 7 is a flowchart showing a fourth method of optimization processing in a processing procedure of the operation of the microcomputer used in the system controller in FIG. 6. FIG. 3 is a diagram illustrating a state of focusing a laser beam on a disk in a bifocal optical pickup. FIG. 16 is a waveform diagram showing various signal waveforms obtained from an output signal when a focus search is performed by the optical pickup corresponding to FIG. FIG. 6 is a waveform diagram showing a focus search in a two-layer disc. 7 is a flowchart showing a processing procedure for discriminating a disc type in an operation of a microcomputer used in the system controller in FIG. 6.

Explanation of reference numerals

1 optical disk 2 optical pickup (optical head)
3 spindle motor 4 motor driver / tracking / focus control circuit (constitutes servo control means with DSV10 and focus search means with system controller 11)
7 EEPROM (non-volatile storage means)
9. Preamplifier (including each arithmetic means, and also constitutes signal processing means with DSP / DSV10)
10 Variable speed transfer controller / memory controller / EFM modulation / demodulation / error correction / servo circuit block (corresponding to the digital signal processor (DSP) / digital servo (DSV) control circuit in FIG. 6 and constituting error correction means, together with the system controller) Configure the servo-on means)
11 Microcomputer (corresponding to the system controller of FIG. 6, means for setting to a standby state, recording layer determining means, optimizing means, control means, standby state detecting means, comparing means, second control means, time measuring means, counting means, It constitutes control / warning means, control means, comparison means, calculation means)
11e CPU
12, 50, 58 LPF (low-pass filter)
13 DRAM (memory means)
14 Compression / expansion control means (time axis changing means)
16 input means 18 display means 20 temperature sensor (physical state detecting means)
20, 22, 24, 32 Adder 25 Transversal filter (frequency characteristic changing means)
26, 28, 30, 74 Subtractor 34, 78 HPF (high-pass filter: filter means)
36, 37 Envelope detector (envelope generating means)
52 PLL circuit (clock extraction means)
54 comparator 56 integrator (constitutes jitter measuring means together with comparator 54)
Reference Signs List 60 switch 62, 64 pulse generation circuit 66, 70 gate circuit 68, 72 hold circuit 76 equalizer A, B, C, D Four-division optical sensor part used for phase difference method E, F Two sensor parts used for three-beam method

Claims (2)

An optical disc reproducing apparatus for reproducing information recorded on a plurality of recording layers including a first layer and a second layer of a disc-shaped optical recording medium, comprising: memory means for temporarily storing reproduction data; When reading the data, the time axis changing means for reading the data from the memory means at a speed lower than the speed at which the data read from the optical head is written to the memory means, and the tracking control of the optical head and / or the focus control of the optical head. Servo control means for performing, and a means having a standby state when the optical head is not performing a read operation on the optical disk,
Optimizing means capable of optimizing control in the servo control means for each of the plurality of recording layers,
Recording layer determining means for determining which of the plurality of recording layers information reproduction is required from,
When reproduction of information is requested for the first layer, an optimization process is performed by the optimization means on the first layer, a predetermined amount of information is read from the first layer, and stored in the memory means. When information of a first predetermined amount or more is stored in the memory means, the optical head is set to the standby state, information is read out from the memory means to perform a reproducing operation, and the optical information is read out of the second layer. When the amount of information stored in the memory unit is smaller than a second predetermined amount, a predetermined amount of information is read from the first layer to perform the optimization process by the optimizing unit. When the reproduction of information is requested for the second layer, an optimization process is performed on the second layer by the optimization means, and a predetermined amount of information is read from the second layer. When the information is stored in the memory means and the memory means stores a first predetermined amount or more of information, the optical head is set to the standby state, the information is read out from the memory means, and a reproducing operation is performed. Controlling the optimization processing by the optimization means for the recording layers other than the second layer, and when the amount of information stored in the memory means is smaller than a second predetermined amount, Control means for controlling at least after starting the optical disc reproducing apparatus or after loading the optical recording medium, so that a predetermined amount of information is read and stored in the memory means,
And the optimization means is:
Signal quality detection means for detecting the quality of a reproduction signal that is an output signal from the optical head,
Means for optimizing the quality of the output signal of the optical head according to the signal quality detected by the signal quality detection means,
An optical disc reproducing apparatus, comprising: An optical disc reproducing apparatus for reproducing information recorded on a plurality of recording layers including a first layer and a second layer of a disc-shaped optical recording medium, comprising: memory means for temporarily storing reproduction data; When reading the data, the time axis changing means for reading the data from the memory means at a speed lower than the speed at which the data read from the optical head is written to the memory means, and the tracking control of the optical head and / or the focus control of the optical head. A method for optimizing the servo control of an optical disk reproducing apparatus, comprising: a servo control unit for performing a read operation on the optical disk; and a unit for setting a standby state when the optical head is not performing a read operation on the optical disk. After starting the reproducing apparatus or after loading the optical recording medium,
Determining from which of the plurality of recording layers information reproduction is required,
Performing a servo control optimization process on the first layer when information reproduction is required for the first layer;
Reading a predetermined amount of information from the first layer and storing it in the memory means;
When information equal to or more than a first predetermined amount is stored in the memory means, the optical head is set to the standby state, information is read out from the memory means to perform a reproducing operation, and the optimization is performed for the second layer. Performing an operation;
Reading the information from the first layer and storing it in the memory when the amount of information stored in the memory is less than a second predetermined amount;
Performing the optimization process on the second layer when information reproduction is required for the second layer;
Reading a predetermined amount of information from the second layer and storing it in the memory means;
When information of a first predetermined amount or more is stored in the memory means, the optical head is set to the standby state, information is read out from the memory means to perform a reproducing operation, and a recording layer other than the second layer is read. Performing the optimization process for
When the amount of information stored in the memory means is smaller than a second predetermined amount, reading out a predetermined amount of information from the second layer and storing the information in the memory means;
And performing the optimization process,
Performing focus servo control on the optical head;
Performing tracking servo control on the optical head;
Optimizing the quality of the playback signal;
Obtaining the amplitude of the reproduction signal;
A filtering step of extracting a highest frequency band of the reproduction signal,
Obtaining the amplitude of the output signal of the highest frequency band extracted in the filtering step,
Storing each of the obtained amplitudes;
A calculating step of calculating to compare the stored amplitudes;
Generating a control signal that changes the frequency characteristic of the frequency characteristic changing unit in accordance with the operation result obtained in the operation step,
Method for optimizing servo control of an optical disk reproducing apparatus having the same.

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