JP3999881B2 - Optical disc apparatus and control circuit thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical disc apparatus capable of recording / reproducing data, such as a DVD-RAM drive, and a control circuit thereof.
[0002]
[Prior art]
The wobble land groove system is adopted as the physical format of the DVD-RAM. As shown in FIGS. 8 and 9, the wobble / land / groove method has a convex track (groove track) 100 and a concave track (land track) formed on the disk surface as viewed from the side irradiated with the laser beam. In this method, marks are recorded on both tracks 101. A minute waviness called a wobble 102 is formed on the track at a predetermined frequency. Based on the frequency signal obtained by detecting this wobble 102, a rough read channel PLL pull-in can be performed. Yes.
[0003]
Further, the DVD-RAM is provided with a header portion 105 arranged so as to cut the land track 101 and the groove track 100, and bits as address information are recorded in the header portion 105 at the time of manufacture. That is, in the wobble / land groove method, the address can be detected by reading the bits of the header portion 105.
[0004]
However, the header part also disturbs the physical continuity of the land track and groove track. The influence affects the tracking servo and the focus servo that are executed based on the signal detected by the photodetector of the optical pickup. For these controls, the photodetection signal obtained from the header portion acts as noise, causing problems such as servo disturbance, misreading of address information, and occurrence of unnecessary track jumps.
[0005]
[Problems to be solved by the invention]
In a disk drive for recording / reproducing such a wobble / land groove type DVD-RAM, it is necessary to generate an accurate timing for starting data writing to the disk, which is a reference for generating this timing. How to obtain the synchronization signal is one of the issues for product development. There is also a demand for an optimum method for obtaining a synchronization signal that is a reference for generating a reproduction clock when reproducing data from a disk.
[0006]
Accordingly, the present invention provides an optimal timing for starting data writing and an optimal synchronization signal serving as a reference for generating a clock for data reproduction in an optical disc apparatus for recording / reproducing a wobble / land groove type DVD-RAM. The purpose is to provide a method that can be generated.
[0007]
It is another object of the present invention to provide an optical disk apparatus and a control circuit for the optical disk apparatus that can more accurately identify a header area and a data area in a land / groove type disk.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, an optical disc apparatus according to the present invention records or records data on an optical disc having a header area in which address data is recorded in advance and a recording area for a user. In a reproducing optical disc apparatus, light beam irradiating means for irradiating the optical disc with a light beam to form a light beam spot, and receiving light reflected from the optical disc of the light beam spot, and data in the header area and recording area Optically reading and outputting as an electrical signal, preamplifying means for amplifying the output of the light detecting means, Servo signal generation means for generating a servo signal for controlling the light beam irradiation position of the light beam irradiation means from the output of the preamplification means, and light of the light beam irradiation means based on the generated servo signal A light irradiation position control means for controlling the beam irradiation position; From the output of the preamplifier means, the header region is Multiple detections with different detection conditions Header detection means; and each Header detection means Determining whether each of the header region detection results is good or not, and selecting an optimum header detection means from among the plurality of header detection means based on the determination result; and outputting the selected header detection means Synchronize Header synchronization signal generating means for generating a header synchronization signal, and the header synchronization signal Based on the servo signal holding means for holding the servo signal before the header detection means detects the header area, and on the basis of the header synchronization signal, the servo signal output by the servo signal generating means and the servo signal Servo signal switching for switching the servo signal held by the holding means to output to the light irradiation position control means Means.
[0009]
Further, the optical disc apparatus of the present invention is as described in claim 2, A plurality of header detection means for detecting the header region from the output of the preamplification means; Means and said Preamplification From the output of the means Second header detection for detecting the header area more accurately than the first header detection means Means and With It is characterized by that.
[0010]
Further, the optical disc apparatus of the present invention is as described in claim 3, Wobble detection means for detecting wobble from the output of the preamplification means; Said Wobble synchronization signal generation that generates a synchronized wobble synchronization signal from the output of the wobble detection means Means and Further comprising header The synchronization signal generation means is configured to output the header detection means and generate the wobble synchronization signal. means Based on the wobble synchronization signal generated by Header detection Generate a sync signal It is characterized by that.
[0011]
Furthermore, the optical disk device of the present invention is as described in claim 4, Said The method further comprises means for setting an effective interval for detecting the header area from the output of the preamplifier means based on a header synchronization signal.
[0012]
According to the present invention, the synchronization signal is generated from the detection timing of the header area detected from the signal obtained by amplifying the output of the light detection means, and data is recorded on or reproduced from the optical disc by the generated header synchronization signal. In addition, as a means for detecting the header area, a plurality of header detection means having different detection conditions are provided, and the quality of the detection result of the header area by each detection means is determined, and a plurality of header detection is performed based on the determination result. By selecting the optimum header detection means from the means, a more accurate header synchronization signal can be obtained and the reliability can be improved.
[0013]
In addition, a wobble detection means for detecting wobble from the output of the preamplifier means is provided, a wobble synchronization signal synchronized with the wobble detection signal is generated from the output of the wobble detection means, and the header based on the output of the header detection means and the wobble synchronization signal is generated. By generating the detection synchronization signal, a header synchronization signal with higher accuracy can be obtained. Further, by setting an effective section for detecting the header area from the output of the pre-amplifying means based on the header synchronization signal generated by the header synchronization signal generating means, the header area is affected by noise other than the header area. The probability of erroneous detection is reduced, and further improvement in accuracy can be expected.
[0014]
This makes it possible to generate the optimal timing for starting data writing and the optimal synchronization signal that serves as a reference for generating a clock for data reproduction, and more accurately the header area and data area on the disc. Can be identified.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0016]
FIG. 1 is a diagram showing a configuration of a DVD-RAM drive as an optical disc apparatus according to an embodiment of the present invention. The “... Means” described below is provided by, for example, a chip mounted on a substrate or other circuits.
[0017]
The reflected light of the laser irradiated from the optical pickup to the optical disk 1 which is a DVD-RAM medium is input to the light detection means 2 in the optical pickup, where it is converted into an electrical signal and then amplified by the preamplification means 3. The The amplified signal 21 is input to the tracking error signal generation unit 4, the focus error signal generation unit 5, the header leading edge detection unit 6, the header rough detection unit 7, and the wobble detection unit 8, respectively.
[0018]
The tracking error signal generation unit 4 extracts tracking error information included in the amplified signal 21 and outputs it as a tracking error signal 22. The tracking error signal 22 is input to the changeover switch 9 and the tracking error signal holding means 10, respectively.
[0019]
The tracking error signal holding means 10 holds the value of the tracking error signal 22 at the input start timing of the tracking error holding switching control signal 24 given from the control means 20. The changeover switch 9 selects either the output of the tracking error signal generating means 4 or the output of the tracking error signal holding means 10 based on the tracking error holding switching control signal 24 given from the control means 20, and the tracking servo control means. 11 to output.
[0020]
Based on the tracking error signal selected by the changeover switch 9, the tracking servo control means 11 moves the laser light spot irradiated by the light detection means 2 along a track (land track or groove track) on the optical disc 1. As described above, the position of the optical pickup having the light detecting means 2 in the disk radial direction is controlled.
[0021]
The control means 20 detects the tracking error signal immediately before entering the section where the desired characteristic is interrupted as the tracking error signal 22 due to the structure of the signal recording surface of the DVD-RAM media (section where the light spot passes through the header area in FIGS. 8 and 9). The value of 22 is held in the tracking error signal holding means 10, the output of the tracking error signal holding means 10 is selected by the changeover switch 9 in that section, and the output of the tracking error signal generating means 4 is selected in the other sections. The tracking error holding switching control signal 24 is output.
[0022]
The focus error signal generation unit 5 extracts focus error information included in the amplified signal 21 and outputs it as a focus error signal 23. The focus error signal 23 is input to the changeover switch 12 and the focus error signal holding means 13, respectively.
[0023]
The focus error signal holding means 13 holds the value of the focus error signal 23 at the input start timing of the focus error holding switching control signal 25 given from the control means 20. The changeover switch 12 selects either the output of the focus error signal generating means 5 or the output of the focus error signal holding means 13 based on the focus error holding change control signal 25 given from the control means 20, and the focus servo control means. 14 to output.
[0024]
The focus servo control means 14 focuses the light detection means 2 on the basis of the signal selected by the changeover switch 12 so that the disk surface on the optical disk 1 is positioned within the beam waist of the laser irradiated by the light detection means 2. Control the position of the direction.
[0025]
The control means 20 has a focus error signal immediately before entering a section where a desirable characteristic is interrupted as a focus error signal 23 due to the structure of the signal recording surface of the DVD-RAM medium (section where the light spot passes through the header area in FIGS. 8 and 9). The value of 23 is held in the focus error signal holding means 13, the output of the tracking error signal holding means 10 is selected by the changeover switch 9 in that section, and the output of the focus error signal generating means 5 is selected in the other sections. The focus error retention switching control signal 25 is output to
[0026]
The header leading edge detection means 6 extracts header leading edge position information from the input amplified signal 21, and outputs a header leading edge detection signal 26, which is a pulse having a certain time width representing the header leading edge position information. It outputs to the header detection selection means 15 and the control means 20. The control means 20 inputs a header detection selection control signal 32 that is a pulse having a certain time width to the header detection selection means 15. The header detection / selection means 15 receives the header detection / selection control signal 32, and masks (selects) the input header leading edge detection signal 26 with the header detection / selection control signal 32, thereby generating a pulse due to noise or the like. A detection result that does not indicate the original header position is removed, and a leading edge detection signal 29 that is improved in correspondence with the original header leading edge position is output to the signal selection means 18.
[0027]
The header rough detection means 7 generates a header rough detection signal 27, which is a pulse having a certain time width representing rough position information of the header position that can be detected even during traversal, from the input amplified signal 21, and the header detection selection means 16 And output to the control means 20.
[0028]
The control means 20 inputs a header detection selection control signal 33 that is a pulse having a certain time width to the header detection selection means 16. The header detection / selection means 16 receives the header detection / selection control signal 33, and masks (selects) the input header rough detection signal 27 with the header detection / selection control signal 33, so that it is a pulse generated by noise or the like. A detection result that does not indicate the header position is removed, and a header rough detection signal 30 with improved correspondence with the original header position is output to the signal selection means 18. The wobble detection means 8 receives the amplified signal 21, extracts the wobble component included in the amplified signal 21 when the track of the optical disc 1 includes wobble, and outputs it as a wobble detection signal 28. The wobble detection signal 28 is input to the wobble synchronization signal generation means 17, and the wobble synchronization signal 31 obtained by interpolating the omission of the wobble detection signal 28 is input to the signal selection means 18.
[0029]
The control means 20 is a signal selection control signal for selecting one or more of the header leading edge detection means 6, the header rough detection means 7, the wobble detection means 8 and other inputs inputted to the signal selection means 18. 38 is input to the signal selection means 18. The signal selection unit 18 outputs the selected signal 35 to the header detection synchronization signal generation unit 19. The header detection synchronization signal generation means 19 outputs a signal 36 synchronized with the input signal 35 to the control means 20.
[0030]
The header detection synchronization signal generating means 19 has a plurality of predetermined different gains, and selects a gain according to the gain selection control signal 37 output from the control means 20.
[0031]
The header detection synchronization signal generation means 19 detects the phase difference and period difference between the signal 35 input from the signal selection means 18 and the output signal 36, and based on the synchronization method selection control signal 34 output from the control means 20, The input signal 35 and the output signal 36 are synchronized by selectively using the phase difference information or the period difference information.
[0032]
Further, the control unit 20 predicts the header area based on the inputted synchronization signal 36, and at the timing immediately before the header area determined from the predicted header position, the tracking error signal holding switching control signal 24 and the focus error signal holding switching control. By outputting the signal 25, the tracking error signal holding means 10 holds the value of the tracking error signal immediately before the header area, and the focus error signal holding means 13 receives the focus error signal immediately before the header area. Hold. As a result, the tracking servo and focus servo are not affected by the header area, and stable tracking servo and focus servo can be maintained.
[0033]
Further, in order to improve the quality of the header rough detection signal 27, the control means 20 generates a header rough detection selection control signal 33 having a certain time width based on the predicted header position. The control means 20 determines whether or not the input header rough detection signal 27 falls within the time width indicated by the header rough detection selection control signal 33 generated based on the predicted header position, and the determination result, for example, the time width Whether the header rough detection state is good or not is determined from the number of times the header leading edge detection signal 26 does not continuously enter the header. And the control means 20 changes the time width which the header rough detection selection control signal 33 shows optimally according to the quality of the judged header rough detection condition.
[0034]
Further, the control means 20 determines the quality of the header leading edge detection signal 26, and prevents the influence of erroneous detection and improves the detection accuracy. The header leading edge detection selection control signal 32 having a certain time width is provided. Is generated and output based on the predicted header position. Then, the control means 20 determines whether or not the header leading edge detection signal 26 falls within the time width indicated by the detection selection control signal 32, determines the quality of the header leading edge detection status based on the number of times, and the determination result For example, the quality of the header leading edge detection status is judged from the number of times the header rough detection signal 27 does not continuously enter within the time width. And the control means 20 changes the time width which the header leading edge detection selection control signal 32 shows optimally according to the quality of the judged header leading edge detection condition.
[0035]
The control means 20 selects a synchronization method according to the detection situation by outputting a gain selection control signal 37 and a synchronization method selection control signal 34 according to the quality of the header rough detection situation and the header leading edge detection situation.
[0036]
Further, the control means 20 outputs a signal selection control signal 38 to the signal selection means 18 in accordance with the quality of the header rough detection situation and the header leading edge detection situation, so that the most reliable header can be obtained under the detection situation at that time. A detection signal is selected and a synchronization signal 36 is created.
[0037]
Here, the control means 20 generates a header leading edge detection selection control signal 32 and a header rough detection selection control signal 33.
(1) Mask the header itself detected from the header position signal.
(2) Mask the header that appears next to the header detected from the header position signal.
(3) The header is masked at the timing of each output of the header detection synchronization signal generating means 19. Are output using any one of the methods.
[0038]
Further, the output 36 of the header detection synchronization signal generation means 19 is passed to the subsequent processing means,
Timing generation for lead channel PLL pull-in
・ Start timing generation to write data to disk
Used to do etc.
[0039]
Next, the operation of this embodiment will be described with reference to FIGS. 2 to 5, taking as an example the case of generating a header detection synchronization signal from each output of the header leading edge detection means 6, header rough detection means 7, and wobble detection means 8 I will explain.
[0040]
First, in FIG. 2, the control means 20 inputs a signal selection control signal 38 to the signal selection means 18 so as to select the output of the spindle FG detection means 41 that detects the rotation speed of the spindle motor 39 that drives the optical disk ( Step 201). The spindle FG detection means 41 generates a signal 42 corresponding to the header interval determined by the FG output 40 of the spindle motor 39 according to the current disk radius position. This frequency-divided signal 42 is given to the control means 20 as it is (step 202).
[0041]
Here, the control means 20 determines whether or not the disk rotation speed has entered a predetermined range based on the header synchronization signal 36 of the input FG frequency division signal 42 (step 203), and if not, returns to step 202. Thus, the generation of the header synchronization signal 36 from the FG frequency division signal 42 (35) is continued.
[0042]
When the disk rotation speed is within the predetermined range, the control means 20 sets the signal selection control signal 38 so as to select the output of the header rough detection means 7 (the output of the header detection selection means 16) in FIG. The signal is input to the signal selection means 18 (step 301). The header rough detection means 7 detects a header rough detection having a fixed time width representing rough position information of the header position that can be detected even during traversal (tracking servo is OFF) from the amplified signal 21 of the signal detected by the light detection means 2. A signal 27 is generated.
[0043]
The header detection by the header rough detection means 7 and the header leading edge detection means 6 is performed by detecting header components appearing in the output waveform of the light detection means 2 according to predetermined criteria.
[0044]
The header rough detection signal 27 output from the header rough detection means 7 is input to the header detection selection means 16 where the noise is removed, and the signal is selected as a pulsed header rough detection signal 30 indicating the header position with high quality. Output to means 18. The header rough detection signal 30 is input to the header detection synchronization signal generation unit 19 through the signal selection unit 18, and the header detection synchronization signal generation unit 19 receives the header synchronization signal synchronized with the header rough detection signal 30 (35). 36 is generated (step 302) and provided to the control means 20.
[0045]
Here, the control means 20 generates each timing of the tracking error signal holding switching control signal 24 and the focus error signal holding switching control signal 25 with reference to the inputted header synchronization signal 36 (step 303). That is, the control means 20 outputs the tracking error signal holding switching control signal 24 and the focus error signal holding switching control signal 25 at the timing immediately before the predicted header position with reference to the header synchronization signal 36, so that the immediately preceding header position is output. Control is performed so that the tracking error signal holding means 10 and the focus error signal holding means 13 hold the tracking error signal and the focus error signal.
[0046]
Next, the control means 20 generates header detection selection control signals 32 and 33 on the basis of the header synchronization signal 36 and outputs the header detection selection control signals 32 and 33 to the header detection selection means 15 and 16 as a protection window for noise removal and the like. A header arrival detection window used to confirm the reliability of header detection is generated (step 304). Both the header arrival detection window and the protection window are set within the range including the header position from the same header synchronization signal 36, but the length and position of both may or may not match.
[0047]
Subsequently, in step 305, the control unit 20 superimposes the header rough detection signal 27 directly taken from the header rough detection unit 7 and the generated header arrival detection window on the time axis, and the header rough detection signal 27 arrives at the header. Judge whether it is in the detection window. As a result of this determination, when the header arrival detection window where the header rough detection signal 27 does not enter is generated a predetermined number of times (for example, three times) (step 305), the process returns to step 201 shown in FIG. Is switched to the output of the spindle FG detection means 41. Further, as a result of the above determination, when the header arrival detection window in which the header rough detection signal 27 does not enter occurs continuously a predetermined number of times (for example, 3 times) (step 306), the process proceeds to step 401 shown in FIG. In other cases, the process returns to step 302 in FIG. 3 to continue the above-described header rough detection.
[0048]
In step 401 of FIG. 4, the control means 20 inputs the signal selection control signal 38 to the signal selection means 18 so as to select the output of the header leading edge detection means 6 (the output of the header detection selection means 15) (step 401). ). The header leading edge detection means 6 generates a header leading edge detection signal 29 having a certain time width representing header position information that can be detected when the tracking servo is turned on, from the amplified signal 21 of the signal detected by the light detection means 2. To do. The header leading edge detecting means 6 is configured to change the waveform of the amplified signal 21 corresponding to the header position at another position when the tracking servo is turned on, that is, under a situation where the fluctuation of the amplified signal 21 is relatively small (compared to when the tracking servo is turned off) This is performed using a threshold set so as to be distinguishable from the signal waveform.
[0049]
The header leading edge detection signal 29 generated by the header leading edge detection means 6 is input to the header detection selection means 15, where the noise is removed and the pulse-like header leading edge showing the header position in high quality. The detection signal 29 is output to the signal selection means 18. The header leading edge detection signal 29 is input to the header detection synchronization signal generation means 19 through the signal selection means 18, and the header detection synchronization signal generation means 19 synchronizes with the header leading edge detection signal 29 (35). The header synchronization signal 36 to be generated is generated (step 402) and given to the control means 20.
[0050]
Here, the control means 20 generates the timings of the tracking error signal holding switching control signal 24 and the focus error signal holding switching control signal 25 based on the inputted header synchronization signal 36 as in the case of header rough detection (step 403). ). That is, the control means 20 outputs the tracking error signal holding switching control signal 24 and the focus error signal holding switching control signal 25 at the timing immediately before the predicted header position with reference to the header synchronization signal 36, so that the immediately preceding header position is output. Control is performed so that the tracking error signal holding means 10 and the focus error signal holding means 13 hold the tracking error signal and the focus error signal.
[0051]
Next, as in the case of header rough detection, the control means 20 generates header detection selection control signals 32 and 33 on the basis of the header synchronization signal 36 and protects the header detection selection means 15 and 16 for noise removal and the like. A header arrival detection window that is output as a window and used to confirm the reliability of the header leading edge detection is generated (step 404).
[0052]
Subsequently, in step 405, the control means 20 superimposes the header leading edge detection signal 26 directly taken from the header leading edge detection means 6 and the generated header arrival detection window on the time axis, thereby obtaining the header leading edge. It is determined whether or not the detection signal 26 is within the header arrival detection window. As a result of this determination, if the header arrival detection window where the header leading edge detection signal 26 does not enter is generated a predetermined number of times (for example, three times) (step 305), the process returns to step 301 shown in FIG. The output of the means 18 is switched to the output of the header rough detection means 7. Further, as a result of the above determination, when the header arrival detection window in which the header leading edge detection signal 26 does not enter is continuously generated a predetermined number of times (for example, 3 times) (step 406), the process proceeds to step 501 shown in FIG. In other cases, the process returns to step 402 in FIG. 4 to continue the above-described header leading edge detection.
[0053]
In step 501 of FIG. 5, the control means 20 uses the signal selection control signal 38 to select the output of the wobble detection means 8 together with the output of the header leading edge detection means 6 (output of the header detection selection means 15). 18
[0054]
The header leading edge detection signal 29 generated by the header leading edge detection means 6 (header detection selection means 15) is input to the header detection selection means 15, where the noise is removed and the pulse indicating the header position with high quality is obtained. A header leading edge detection signal 29 is output to the signal selection unit 18, while the wobble detection signal 28 generated by the wobble detection unit 8 is input to the wobble synchronization signal generation unit 17, where the wobble detection signal The wobble synchronization signal 31 obtained by interpolating the omission of 28 is input to the signal selection means 18.
[0055]
The header leading edge detection signal 29 and the wobble synchronization signal 31 selected by the signal selection means 18 are input to the header detection synchronization signal generation means 19, and the header detection synchronization signal generation means 19 inputs the header leading edge detection signal 29 and the wobble. A header synchronization signal 36 synchronized with the synchronization signal 31 (35) is generated (step 501) and provided to the control means 20.
[0056]
The control means 20 controls the tracking error signal holding switching control signal 24 and the focus error signal based on the input header leading edge detection signal 29 and the wobble synchronization signal 31 (35) as in the case of header rough detection and header leading edge detection. Each timing of the holding switching control signal 25 is generated (step 502).
[0057]
Next, as in the case of header rough detection and header leading edge detection, the control means 20 sets the header detection selection control signals 32 and 33 on the basis of the input header leading edge detection signal 29 and the wobble synchronization signal 31 (35). It is generated and output to the header detection selection means 15 and 16 as a protection window for the purpose of noise removal and the like, and a header arrival detection window used for confirming the reliability of the header position detection is generated (step 503). ).
[0058]
Subsequently, in step 504, the control means 20 superimposes the header leading edge detection signal 26 directly taken from the header leading edge detection means 6 and the generated header arrival detection window on the time axis, thereby obtaining the header leading edge. It is determined whether or not the detection signal 26 is within the header arrival detection window. As a result of this determination, if the header arrival detection window where the header leading edge detection signal 26 does not enter is generated a predetermined number of times (for example, three times) (step 504), the process returns to step 401 shown in FIG. The output of the means 18 is switched to the output of only the header leading edge detection means 6. In other cases, the process returns to step 501 in FIG. 5 to continue the above-described header leading edge detection and wobble detection.
[0059]
FIG. 6 shows the effect of the header area on the tracking error signal and the focus error signal in comparison with the conventional case and the case of the present embodiment. In this embodiment, the signal immediately before the header area is held, and the header area section performs tracking control or focus control based on the held tracking error signal or focus error signal. Is not affected by the header area, and stable tracking servo and focus servo can be maintained.
[0060]
Further, as shown in FIG. 7, the header detection synchronization signal generator 19 generates the synchronization signal 36 from the header synchronization signal 35 obtained by the header leading edge detection means 6, the header rough detection means 7, the wobble detection means 8 and others. Based on the header synchronization signal 36, the output of the focus error holding means is selected during the header area period, and the output of the focus error signal generating means is selected during the non-header area period. It becomes difficult to be affected by the detection failure of the header area due to scratches or the like, and it becomes possible to improve the reproduction quality.
[0061]
【The invention's effect】
As described above, according to the present invention, it is possible to generate an optimal timing for starting data writing and an optimal synchronization signal that serves as a reference for generating a clock for data reproduction. In addition, as a means for detecting the header area, a plurality of header detection means having different detection conditions are provided, and the quality of the detection result of the header area by each detection means is determined, and a plurality of header detection is performed based on the determination result. By selecting the optimum header detection means from the means, a more accurate header synchronization signal can be obtained and the reliability can be improved. Furthermore, a wobble detection means for detecting wobble from the output of the preamplifier means is provided, a wobble synchronization signal synchronized with the wobble detection signal is generated from the output of the wobble detection means, and the header based on the output of the header detection means and the wobble synchronization signal is generated. By generating the detection synchronization signal, a header synchronization signal with higher accuracy can be obtained. Further, by setting an effective section for detecting the header area from the output of the pre-amplifying means based on the header synchronization signal generated by the header synchronization signal generating means, the header area is affected by noise other than the header area. The probability of erroneous detection is reduced, and further improvement in accuracy can be expected.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a DVD-RAM drive as an optical disc apparatus according to an embodiment of the present invention.
FIG. 2 is a flowchart showing a procedure for detecting a header synchronization signal in the DVD-RAM drive of the embodiment of FIG. 1, and is a flowchart showing an operation immediately after the start of disk rotation.
3 is a flowchart showing a header synchronization signal detection procedure in the DVD-RAM drive of the embodiment of FIG. 1, and is a flowchart showing an operation of header rough detection.
4 is a flowchart showing a header synchronization signal detection procedure in the DVD-RAM drive of the embodiment of FIG. 1 and a header leading edge detection operation. FIG.
FIG. 5 is a flowchart showing a header synchronization signal detection procedure in the DVD-RAM drive of the embodiment of FIG. 1 and a header synchronization signal generation procedure based on header leading edge detection and wobble detection.
FIG. 6 is a diagram comparing the influence of a header area on a tracking error signal and a focus error signal between the conventional case and the present embodiment.
FIG. 7 is a diagram illustrating a synchronization signal of a header detection signal.
FIG. 8 is a diagram showing a physical format of a DVD-RAM.
9 is a diagram showing a configuration of a header part in the physical format of the DVD-RAM in FIG. 8;
[Explanation of symbols]
1 ... Optical disc
2 ... Photodetection means
3. Preamplification means
4 ... Tracking error signal generating means
5 ... Focus error signal generating means
6 ... Header leading edge detection means
7 ... Header rough detection means
8 ... Wobble detection means
9, 12 ... changeover switch
10: Tracking error signal holding means
11 ... Tracking servo control means
13: Focus error signal holding means
14: Focus servo control means
15 ... Header detection selection means
16 ... Header detection selection means
17 ... Wobble synchronization signal generating means
18 ... Signal selection means
19... Header detection synchronization signal generation means
20 ... Control means

Claims (8)

In an optical disc apparatus for recording or reproducing data with respect to an optical disc having a header area in which address data is recorded in advance and a recording area for a user,
A light beam irradiation means for irradiating the optical disk with a light beam to form a light beam spot;
Photodetection means for receiving reflected light from the optical disc of the light beam spot, optically reading the data in the header area and the recording area, and outputting the data as an electrical signal;
A preamplifier for amplifying the output of the light detector;
Servo signal generation means for generating a servo signal for controlling the light beam irradiation position of the light beam irradiation means from the output of the preamplifier means;
A light irradiation position control means for controlling a light beam irradiation position of the light beam irradiation means based on the generated servo signal;
Detecting the header region from the output of the preamplifying means, and a plurality of header detecting means having different detection conditions ;
Means for determining the quality of the detection result of the header area by each header detection means, and means for selecting an optimum header detection means from the plurality of header detection means based on the determination result;
Header synchronization signal generation means for generating a header synchronization signal synchronized with the output of the selected header detection means ;
Servo signal holding means for holding the servo signal before the header detection means detects a header area based on the header synchronization signal ;
Servo signal switching means for switching between the servo signal output from the servo signal generating means and the servo signal held by the servo signal holding means based on the header synchronization signal and outputting the servo signal to the light irradiation position control means. An optical disc apparatus characterized by: A plurality of header detection means, a first header detection means for detecting the header region from the output of the preamplification means;
Second header detection means for detecting the header region more accurately than the first header detection means from the output of the preamplifier means;
Optical disk apparatus according to claim 1, characterized in that it comprises a. Wobble detection means for detecting wobble from the output of the preamplification means;
Wobble synchronization signal generation means for generating a wobble synchronization signal synchronized with the output from the output of the wobble detection means;
Further comprising
Before Kihe header synchronizing signal generating means, according to claim 1, wherein the generating a header detection sync signal based on the output as well as wobble synchronization signal generated by the wobble synchronization signal generating means of said header detecting means Or the optical disc device according to 2 ; 4. The optical disc apparatus according to claim 1 , further comprising means for setting an effective section for detecting the header area from the output of the preamplifier means based on the header synchronization signal. In an optical disc apparatus for recording or reproducing data with respect to an optical disc having a header area in which address data is recorded in advance and a recording area for a user,
A light beam irradiation means for irradiating the optical disk with a light beam to form a light beam spot;
Photodetection means for receiving reflected light from the optical disc of the light beam spot, optically reading the data in the header area and the recording area, and outputting the data as an electrical signal;
A preamplifier for amplifying the output of the light detector;
Servo signal generation means for generating a servo signal for controlling the light beam irradiation position of the light beam irradiation means from the output of the preamplifier means;
A light irradiation position control means for controlling a light beam irradiation position of the light beam irradiation means based on the generated servo signal;
Detecting the header region from the output of the preamplifying means, and a plurality of header detecting means having different detection conditions ;
Wherein determining the acceptability of the detection result of the header area according to the f header detection means, respectively, means for selecting an optimum header detecting means from among the plurality of header detection unit based on the determination result,
Header synchronization signal generation means for generating a header synchronization signal synchronized with the output of the selected header detection means ;
Servo signal holding means for holding the servo signal before the header detection means detects a header area based on the header synchronization signal ;
Servo signal switching means for switching between the servo signal output from the servo signal generating means and the servo signal held by the servo signal holding means based on the header synchronization signal and outputting the servo signal to the light irradiation position control means. A control circuit for an optical disc apparatus. A plurality of header detection means, a first header detection means for detecting the header region from the output of the preamplification means;
Second header detection means for detecting the header region more accurately than the first header detection means from the output of the preamplifier means;
6. The control circuit for an optical disc apparatus according to claim 5, further comprising: Wobble detection means for detecting wobble from the output of the preamplification means;
Wobble synchronization signal generation means for generating a wobble synchronization signal synchronized with the output from the output of the wobble detection means;
Further comprising
Before Kihe header synchronizing signal generating means, according to claim 5, characterized in that generating the header detection sync signal based on the output as well as wobble synchronization signal generated by the wobble synchronization signal generating means of said header detecting means Or a control circuit for an optical disk apparatus according to 6 ; 8. The control circuit for an optical disk apparatus according to claim 5 , further comprising means for setting an effective section for detecting the header area from the output of the preamplifier means based on the header synchronization signal.

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