JP2004319089A - Prepit detection device and prepit detection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a prepit detection device capable of accurately detecting a prepit signal even when noise is superimposed near the prepit signal. <P>SOLUTION: This prepit detection device detects a prepit on a recording medium on which information tracks are wobbled and recorded in a frequency about a reference clock for controlling the rotation of the recording medium and prepits having a prescribed phase relation to the wobbled information tracks and having sink information and data information are formed. This prepit detecting device is provided with a pickup for emitting a track and an adjacent track, an extracting means for extracting wobbling signal components from an output of the pickup, a generating means for generating a reference signal obtained by variably controlling a signal level in accordance with a control signal, an extracting means for comparing a wobbling signal with a reference signal to extract a signal component corresponding to a prepit, an evaluating means for evaluating a signal component corresponding to a prepit of a sink among signal components corresponding to the extracted prepit, and a reference signal control means for generating a control signal for variably controlling the signal level of the reference signal in accordance with results of the evaluating means to supply the control signal to the generating means. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a pre-pit detection device and a pre-pit detection method for accurately reproducing a signal used for rotation control of a recording medium, such as a synchronization signal or a wobbling signal, recorded in advance on the recording medium.

    2. Description of the Related Art Conventionally, rotation control information and the like used for rotation control of a synchronization signal or a wobbling signal or the like necessary for a position search or the like when recording information such as image information is recorded (hereinafter, these are collectively referred to as pre-recording information) As a recording medium on which information can be additionally recorded based on pre-recording information, a CD-R (CD-Recordable) which is an optical disk having a recording capacity similar to that of a CD is known.

  In the CD-R, an information track (groove track or land track) on which recording information is to be recorded is converted into a signal in which pre-recording information to be recorded is FM-modulated in advance in a pre-formatting step at the time of manufacturing the CD-R. Pre-recording information was recorded by wobbling at a corresponding frequency.

  When recording information is actually recorded on a conventional CD-R, the wobbling frequency of the wobbled track is detected, and a reference clock for controlling the rotation of the CD-R based on the wobbling frequency is detected. A drive signal for controlling the rotation of a spindle motor that rotates the CD-R based on the extracted reference clock is generated, and a recording clock signal including timing information synchronized with the rotation of the CD-R is generated. Was.

  Regarding the address information indicating the address on the CD-R required when recording the recording information, the pre-recording information is reproduced at the time of recording the recording information, and based on this, the recording position is detected and the recording information is recorded. I was

  However, among the high-density recording media such as DVDs (Digital Versatile Disks) whose recording densities have been dramatically improved compared to conventional CDs (Compact Disks) and the like, WO (Write Once) type recording media (DVDs) that can be additionally written -R) and rewritable recording media (DVD-RW), particularly, for example, DVD-R and DVD-RW, the recording density is increased, and the distance between adjacent information tracks is larger than that of CD-R. Since it is about half, even if it is attempted to obtain pre-recording information by wobbling information tracks on a DVD-R or DVD-RW as in the prior art, the wobbling frequencies of adjacent information tracks interfere with each other, and the information is accurately obtained. In some cases, the wobbling frequency cannot be detected.

  Therefore, in a DVD-R or DVD-RW, the information track (for example, a groove track) is wobbled at a frequency based on the reference clock, and in addition, the pre-recording information is written between the two information tracks. Are recorded by forming prepits corresponding to prerecording information on a track (for example, a land track). Further, in order to enable the reference clock to be reproduced from the pre-pits as necessary, the pre-pits are formed substantially uniformly over the entire surface of the DVD-R.

  Conventionally, pre-recording information is obtained by detecting such pre-pits, and accurate rotation control and recording control are performed based on the pre-recording information.

Conventional detection of prepits has been performed by the following method.
First, as shown in FIG. 8, a gate signal synchronized with a signal containing a wobbling frequency component obtained by irradiating the information track with a light beam (hereinafter, referred to as a wobbling signal) is generated.
Further, by comparing the wobbling signal with a threshold signal having a predetermined fixed value, only a signal exceeding the threshold signal having a predetermined fixed value is extracted.
And, by taking the logical product of the extracted signal and the gate signal, the pre-pit signal superimposed on the wobbling signal is extracted.

Therefore, when a noise component is included in the wobbling signal, the level difference between the pre-pit portion on the wobbling signal and other portions is small, and the noise component may be erroneously detected as a pre-pit detection signal. Had a point. Further, Japanese Patent Application Laid-Open No. H10-32081 discloses a proposal for improving the erroneous detection, but has a problem that noise generated near the prepit signal cannot be removed. Further, the wobbling signal is a base signal for generating a recording clock signal for performing recording, and needs to be a high-precision frequency signal, but a pre-pit signal superimposed on the wobbling signal is If it cannot be removed accurately, an error occurs in the frequency signal in the wobbling signal, and the jitter of the recording clock signal cannot be reduced, resulting in a problem that high-density recording cannot be performed. In order to improve this, there is also a method of passing the wobbling signal through a bandpass filter having a high Q and a higher order. However, in this method, if the rotation speed of the recording medium changes, a correct wobbling signal cannot be obtained. Since the amplitude of the wobbling signal, which will be described later, fluctuates due to the influence of interference of an adjacent track and the like, the detection of the pre-pit signal is detected using the amplitude of the wobbling signal. The phase relationship between the wobbling signal on which the pre-pit signal is superimposed and the wobbling signal passed through a bandpass filter having a higher Q and a higher order is shifted, and there is a problem that accurate detection is not possible.
In such a recording / reproducing apparatus, portable equipment such as a recording apparatus such as a mini disk which has already been commercialized is demanded from the market. There is a problem that it is necessary to realize a circuit configuration operable with a power supply voltage.

  Therefore, the present invention solves the above-described problems, and provides a pre-pit detection device and a pre-pit detection method that can accurately detect a pre-pit signal even when a noise component is superimposed on a wobbling signal. By improving the signal quality of the signal, it is possible to improve the quality of the clock signal for recording and increase the recording density, and also improve the quality of the recording signal, and operate with low power consumption and low power supply voltage. It is intended to realize a simple circuit configuration.

In order to solve the above-mentioned problems, the present invention provides a pre-pit detection device and a pre-pit detection method having the following configurations.
(1) An information track is wobbled and recorded at a frequency related to a reference clock for controlling rotation of a recording medium, and a prepit having a predetermined phase relationship with the wobbled information track and having sync information and data information is recorded. A pre-pit detection device that detects the pre-pit when recording information on a formed recording medium,
Pickup means for simultaneously irradiating the information track and an adjacent track adjacent to the information track with a light beam, and outputting a signal based on reflected light of the light beam from the information track and the adjacent track,
Wobbling signal extraction means for extracting the wobbling signal component from an output signal of the pickup means,
Reference signal generating means for generating a reference signal having a signal level variably controlled according to a control signal,
Pre-pit signal extraction means for comparing the wobbling signal with the reference signal and extracting a pre-pit signal component corresponding to the pre-pit;
Evaluation means for evaluating the presence of a pre-pit signal component corresponding to the pre-pit of the sync information among the pre-pit signal components corresponding to the extracted pre-pit,
And a reference signal control means for generating a control signal for variably controlling the signal level of the reference signal in accordance with the evaluation result of the evaluation means and supplying the control signal to the reference signal generation means. apparatus.
(2) The pre-pit detection device according to claim 1, wherein the reference signal is a signal obtained by superimposing a DC voltage of a predetermined value based on the extracted wobbling signal.
(3) The pre-pit detection device according to claim 1 or 2, wherein the reference signal is switched at the time of reproduction without a signal, at the time of reproduction of a recorded area, and at the time of recording.
(4) An information track is wobbled and recorded at a frequency related to a reference clock for controlling rotation of a recording medium, and a pre-pit having a predetermined phase relationship with the wobbled information track and having sync information and data information is recorded. A pre-pit detection method for detecting the pre-pit when recording information on a formed recording medium,
Simultaneously irradiating the information track and an adjacent track adjacent to the information track with a light beam, and outputting a detection signal based on reflected light of the light beam from the information track and the adjacent track,
Extracting a wobbling signal for extracting the wobbling signal component from the detection signal;
Generating a reference signal whose signal level is variably controlled according to the control signal;
Extracting the pre-pit signal component corresponding to the pre-pit by comparing the wobbling signal and the reference signal;
Evaluating the presence of a pre-pit signal component corresponding to the pre-pit of the sync information among the pre-pit signal components corresponding to the extracted pre-pit,
Generating a control signal for variably controlling the signal level of the reference signal in accordance with the evaluation result.
(5) The prepit detection method according to claim 4, wherein the reference signal is a signal obtained by superimposing a DC voltage of a predetermined value based on the extracted wobbling signal.
(6) The prepit detection method according to (4) or (5), wherein the reference signal comprises a step of switching during reproduction without a signal, during reproduction of a recorded area, and during recording.
(7) The pre-pit detection device according to (1) or (2), wherein the reference signal is switched according to a recording power value or an erasing power value during recording.
(8) The prepit detection method according to (4) or (5), wherein the reference signal is switched according to a recording power value or an erasing power value during recording.

The present invention variably controls the threshold value of the pre-pit signal superimposed on the wobbling signal with the same phase and frequency as the wobbling signal extracted from the reproduction signal so that the quality of the obtained pre-pit signal is the best. This has the advantage that the pre-pit signal can be detected with high accuracy even when the noise component is superimposed on the pre-pit signal.
Further, the wobbling signal on which the pre-pit signal is superimposed is multiplied by X, the wobbling signal is accurately extracted, and multiplied by 1 / X again, and compared with the wobbling signal on which the pre-pit signal is superimposed. It is possible to extract. As a result, high-density recording can be performed, and operation can be performed with a low power supply voltage, so that low power consumption can be realized and the load on the global environment can be reduced.

  Next, embodiments of the present invention will be described with reference to the drawings. First, a DVD-R and a DVD-RW as a recording medium on which rotation control information is recorded by forming prepits corresponding to address position information as recording control information and wobbling a groove track to be described later at a predetermined frequency. An example will be described with reference to FIGS.

  The structure of the DVD-R and the DVD-RW of this embodiment will be described with reference to FIG. In FIG. 1, a DVD-R1 is a dye-type DVD-R (or a phase-change DVD-RW) provided with a dye film 5 (or a phase-change film) and capable of writing information only once, and serving as an information track. A groove track 2 and a land track 3 as an adjacent track for guiding a light beam B such as a laser beam as a reproduction light or a recording light on the groove track 2 are formed. Further, a protective film 7 for protecting them and a vapor deposition surface 6 of gold or the like for reflecting the light beam B when reproducing recorded information are provided. The land track 3 has pre-pits 4 corresponding to pre-recording information. The pre-pits 4 are formed before shipping the DVD-R1.

  Further, in the DVD-R1, the groove track 2 is wobbled at a frequency corresponding to the rotation speed of the DVD-R1. The recording of the rotation control information by the wobbling of the groove track 2 is executed before the DVD-Rl is shipped, like the pre-pit 4. When recording information (information such as image information to be originally recorded other than pre-recording information and rotation control information; the same applies hereinafter) is recorded on the DVD-R1, a groove track 2 is recorded in an information recording apparatus described later. , The rotation control information is obtained by detecting the wobbling frequency to control the rotation of the DVD-R 1 at a predetermined rotation speed, and the pre-pit 4 is detected to obtain the pre-recording information in advance and record based on it. The optimum output of the light beam B as light and the like are set, and address information or the like, which is a position on the DVD-R1 where the recording information is to be recorded, is obtained. Recorded in.

  Here, at the time of recording the recording information, the recording information is formed by irradiating the light beam B such that the center thereof coincides with the center of the groove track 2 to form recording information pits corresponding to the recording information on the groove track 2. Form. At this time, the size of the light spot SP is set so that a part thereof is irradiated not only on the groove track 2 but also on the land track 3 as shown in FIG. Then, a bush-pull method (a push-pull method using a photodetector divided by a dividing line parallel to the rotation direction of the DVD-Rl) by using a part of the reflected light of the light spot SP applied to the land track 3 is used. (Hereinafter, referred to as a radial push-pull method)), the pre-recording information is detected from the pre-pits 4 to obtain the brittle information, and the groove track is reflected by the light spot SP applied to the groove track 2. 2, a wobbling signal is detected and a clock signal for rotation control is obtained.

  Next, the recording format of the pre-recording information and the rotation control information recorded in advance on the DVD-R 1 of the present embodiment will be described with reference to FIG. In FIG. 2, the upper part shows the recording format of the recording information, the lower waveform shows the wobbling state of the groove track 2 (the plan view of the groove track 2) for recording the recording information, and the recording information and the groove track. The upward arrow during the wobbling state of No. 2 schematically shows the position where the prepit 4 is formed. Here, in FIG. 2, the wobbling state of the groove track 2 is shown using an amplitude larger than the actual amplitude for easy understanding, and the recording information is recorded on the center line of the groove track 2.

  As shown in FIG. 2, the recording information recorded on the DVD-Rl in this embodiment is divided in advance into each sync frame (EVEN frame / ODD frame) as an information unit. One recording sector is formed by 26 sync frames, and one ECC (Error Correcting Code) block is formed by 16 recording sectors. Note that one sync frame has a length of 1488 times (1488T) a unit length (hereinafter, referred to as T) corresponding to a bit interval defined by a recording format when recording the above-described recording information. In addition, synchronization information SY for synchronizing each sync frame is recorded in the first 14T length portion of one sync frame.

  On the other hand, in this embodiment, the pre-recording information recorded on the DVD-Rl is recorded for each sync frame. Here, in the recording of the pre-recording information by the pre-pit 4, the synchronization signal in the pre-recording information is always indicated on the land track 3 adjacent to the area where the synchronization information SY in each sync frame in the recording information is recorded. Two pre-pits 4 are formed, and two or one of the pre-pits 4 indicate the contents (address information) of pre-recording information to be recorded on the land track 3 adjacent to the first half in the sync frame other than the synchronization information SY. The pre-pits 4 are formed (note that the pre-pits 4 may not be formed in the first half of the sync frame other than the synchronization information SY depending on the contents of the bullet information to be recorded). At this time, in this embodiment, in one recording sector, the pre-pits 4 are provided only in even-numbered sync frames (hereinafter, referred to as EVEN frames) or only in odd-numbered sync frames (hereinafter, referred to as ODD frames). It is formed and pre-recording information is recorded. That is, in FIG. 2, when the pre-pit 4 is formed in the EVEN frame (indicated by the solid line upward arrow in FIG. 2), the pre-pit 4 is not formed in the ODD frame adjacent thereto.

  On the other hand, the groove track 2 is wobbled at a constant wobbling frequency f0 of 140 kHz (one sync frame corresponds to eight waves) over all the sync frames. Then, in the information recording device described later, a signal for controlling the rotation of the spindle motor is detected by detecting the constant wobbling frequency f0.

  Next, a first embodiment of the information recording apparatus according to the present invention will be described with reference to FIGS. In the following description, an embodiment in which the present invention is applied to an information recording apparatus for recording digital information transmitted from a host computer on a DVD-Rl will be described.

  First, the overall configuration and operation of the information recording apparatus according to the present embodiment will be described with reference to FIG. In the following description of the embodiment, the DVD-R1 is formed in advance with the pre-pits 4 including address information and the like on the DVD-R1 and the groove track 2 to be wobbled. Is detected in advance to obtain address information on the DVD-R1, thereby detecting and recording a recording position on the DVD-R1 where digital information is to be recorded.

  The information recording apparatus S shown in FIG. 3 includes a pickup (reproducing) unit, a pickup 10 as a recording unit, a reproducing amplifier 11, a decoder 12, a pre-pit signal decoder 13, a spindle motor 14 as a rotating unit, A servo circuit 15 as control means, a processor (CPU) 16, an encoder 17, a power control circuit 18, a laser drive circuit 19, an interface 20, a wobbling signal extractor 22 as information extraction means, And a filter (BPF) 27. Further, digital information SRR to be recorded is input from the external host computer 21 to the information recording device S via the interface 20.

  Next, the overall operation will be described. The pickup 10 combines a laser diode (not shown), a deflection beam splitter, an objective lens, a photodetector, and the like, irradiates a light beam B to the information recording surface of the DVD-Rl based on the laser drive signal SDL, and Based on the radial push-pull method, the wobbling frequency of the bripit 4 and the groove track 2 is detected to record digital information SRR to be recorded, and when there is already recorded digital information, the light beam B The already recorded digital information is detected based on the reflected light.

  Then, the reproduction amplifier 11 amplifies the detection signal SDT including the information corresponding to the pre-pit 4 output from the pickup 10 and the wobbling frequency of the groove track 2, and corresponds to the pre-pit 4 and the wobbling frequency of the groove track 2. The pre-recording information signal SPP is output, and the amplified signal SP corresponding to the already recorded digital information is output.

  Thereafter, the decoder 12 decodes the amplified signal SP by performing 8-16 demodulation and deinterleaving on the amplified signal SP, and outputs a demodulated signal SDM and a servo demodulated signal SSD.

  The pre-recording information signal SPP output from the reproduction amplifier 11 is input to the wobbling signal extraction unit 22 after high-frequency components are removed by a band pass filter (BPF) 27. The pre-recording information signal SPP output from the reproduction amplifier 11 is also input to the pre-pit signal decoder 13. The reproduction amplifier 11 has an RF ENV detection unit for extracting an RF signal component in a recorded reproduction signal and detecting the RF signal level. When an RF signal is present in the reproduction area, the RF ENV signal obtained from the RF ENV signal is It is supplied to the processor 16.

  The pre-pit signal decoder 13 extracts only a signal obtained by detecting the pre-pit 4 from the pre-recording information signal SPP, outputs a pre-pit detection signal SPDT, decodes this, and decodes the corresponding demodulated pre-pit signal SPD into the CPU 16. Output to

  Further, the wobbling signal extraction unit 22 extracts only the wobbling frequency of the groove track 2 matched with the pre-recording information signal SPP, and outputs the extracted signal SDTT to the servo circuit 15 and the pre-pit signal decoder 13.

  The servo circuit 15 outputs a pickup servo signal SSP for performing focus servo control and tracking servo control in the pickup 10 to the pickup 10 based on the pre-pit detection signal SPDT and the servo demodulation signal SSD. Further, the servo circuit 15 outputs a spindle servo control signal SSS to the spindle motor 14 by using information corresponding to the wobbling frequency f0 included in the extraction signal SDTT supplied from the wobbling signal extraction unit 22 to output the spindle motor 14 Servo control the rotation of.

  The interface 20 encodes the digital information SRR transmitted from the host computer 21 under the control of the processor (CPU) 16 into the information recording device S by processing the digital information SRR. 17 is output.

  The encoder 17 combines an ECC generator (not shown), an 8-16 modulator, a scrambler, and the like to form an ECC block, which is a unit for performing error correction during reproduction, based on the digital information SRR. Are subjected to interleaving, 8-16 modulation, and scramble processing in a predetermined order to generate a modulation signal SRE and supply it to the power control circuit 18.

  The power control circuit 18 outputs a recording signal SD for controlling the output of a laser diode (not shown) in the pickup I0 to the laser drive circuit 19 based on the modulation signal SRE. The laser drive circuit 19 outputs to the optical pickup 10 a laser drive signal SDL for actually driving the laser diode to emit the light beam B based on the recording signal SD.

  The processor (CPU) 16 acquires the pre-recording information by using the input demodulated pre-pit signal SPD, and obtains the digital information corresponding to the position on the DVD-R1 corresponding to the address information corresponding to the acquired pre-recording information. The operation of recording the SRR is controlled. In parallel with these, the processor 16 outputs a reproduction signal SOT corresponding to the already recorded digital information to the outside based on the demodulated signal SDM, and mainly controls the entire information recording apparatus S.

  The information recording device S can also reproduce the information recorded on the DVD-R1. In this case, the reproduced signal SOT is output to the outside via the processor 16 based on the demodulated signal SDM. Will be done.

  Next, a detailed configuration of the pre-pit signal decoder 13 will be described with reference to FIGS. FIG. 4 is a block diagram showing a detailed configuration of the pre-pit signal decoder 13. In FIG. 4, the BPF 27, the wobbling signal extraction unit 22, and the servo circuit 15 are also illustrated in order to explain input signals to the pre-pit signal decoder 13.

  As shown in FIG. 4, the pre-pit signal decoder 13 is supplied with a digital signal of a predetermined level (value) set by a processor (CPU) 16, converts the digital signal into a digital-analog signal, and outputs the digital signal. A threshold setting unit 24 for adding the signal Sph from the peak hold circuit unit 34 for peak-holding the signal SDTT of the wobbling signal extraction unit 22 and the signal from the D / A converter 23 to set a threshold Sref; It includes a comparator 25, an LPP and sync detector 36, and a decoder 26.

  The pre-recording information signal SPP input to the BPF 27 is, for example, a signal containing a high-frequency noise component as shown in FIG. 6A, and this noise is not completely removed even after passing through the BPF 27. Are input to the pre-pit signal decoder 13 and the wobbling signal extraction unit 22 in a state where noise components are included.

  The wobbling signal extraction unit 22 includes a limiter, a BPF, a binarizer, and the like. The wobbling signal extraction unit 22 removes noise and a pre-pit signal component from the pre-recording information signal SPP, and performs wobbling as shown in FIG. An extracted signal SDTT obtained by extracting only the frequency is output to the servo circuit 15.

  For example, as shown in detail in FIG. 5, the servo circuit 15 includes a VCO (Voltage controlled oscillator) 270, a frequency divider (1 / N) 28, a multiplier 29, an amplifier 30, an LPF (Low Pass Filter). The BPF 32 comprises a PLL (Phase Locked Loop) circuit and a binarized PLL signal SPL in synchronization with the extracted wobbling signal SDTT. As shown in FIG. 6C, the PLL signal SPL is a signal having the same phase and the same frequency as the extracted wobbling signal SDTT.

  As described above, since the pre-pits 4 are arranged at predetermined phase positions with respect to the groove track 2 in advance, the positions superimposed on the wobbling signal SPP are also constant.

  Accordingly, as described above, the PLL signal SPL output from the servo circuit 15 is compared with the pre-recording information signal SPP and the predetermined threshold Sref, and a signal SPDT obtained as a signal equal to or higher than the threshold Sref is described later with reference to FIG. By comparing with the sync detection LPP 36 shown in (1), a more accurate pre-pit detection signal can be obtained.

  However, as shown in FIG. 6 (A), the pre-recording information signal SPP has a difference in recording power when reproducing a recorded signal or when recording, in addition to a frequency component corresponding to the wobbling frequency of the groove track 2. Since a high frequency component, which is noise due to the write strategy signal, is included, and this noise component fluctuates greatly due to variations in the disc and pickup, the level difference between the pre-pit portion and other portions is reduced, and the fixed value is a fixed value. It is difficult to accurately detect the pre-pit signal by the method of comparing with the threshold value.

  A signal Sph (FIG. 6D) from a peak hold circuit unit 34 for peak-holding the signal SDTT of the wobbling signal extraction unit 22 shown in FIG. 4 is output from a D / A converter 23 set by a processor (CPU) 16. The signal obtained by adding the DC value in the threshold setting unit 24 is Sref in FIG. Although FIG. 4 shows a configuration including the peak hold circuit section 34, the peak hold circuit section 34 is not essential, and the output signal SDTT of the wobbling signal extraction section 22 is directly supplied to the threshold setting section 24. It is also possible. Further, the amplitude value of the wobbling signal output from the peak hold circuit unit 34 is input to an A / D converter of the processor (CPU) 16, and the D / A converter is converted based on a value obtained by A / D converting the amplitude value. 23 is configured to be adjustable. In this case, even if there is a difference between the amplitude value of the wobble signal and the noise signal superimposed on the wobble signal, it is possible to easily adjust the difference.

  As shown in FIG. 6 (E), FIG. 6 (F) shows a case where the comparator 25 compares the Sref signal to extract a pre-pit signal from Spp. FIG. 6 (G) shows a case where the comparison is performed by the comparator 25, and FIG. 6 (H) shows a case where the comparison is performed by the comparator 25 with the Sref2 signal. FIG. 6 (F) shows a case where the pre-pit signal is normally extracted. It can be seen that this signal becomes an abnormal signal as shown in FIGS. 6 (G) and 6 (H). .

  Therefore, the threshold value for comparing the pre-recording information signal SPP is configured to be variably set as described above, and the quality of the pre-pit detection obtained by comparing the threshold value and the pre-recording information signal SPP is optimized. , It is possible to detect the pre-pit with high accuracy.

  The PLL signal SPL as the synchronization signal used for the amplitude modulation of the present embodiment has the same phase as the pre-recording information signal SPP.

Therefore, by detecting the sync signal of the pre-pit signal and generating the gate of the address signal and the interpolation signal by the LPP and sync detector 36, the comparator SPDT is gated in the H section of the PLL signal SPL. Thus, a more accurate pre-pit signal can be obtained. The pre-pit signal thus obtained may be any of the signals shown in FIG. 6 (F), FIG. 6 (G), or FIG. 6 (H) depending on the threshold. Therefore, as shown in FIG. 7, the LPP and sync detector 36 detects whether a pre-pit (LPP) signal can be obtained at a predetermined interval timing during the wobble window (Sph section) (step 100), and If a signal is obtained (Y), the current process is determined to be appropriate, and the determination information is transmitted to the processor (CPU) 16 (step 101). If not (N), the process proceeds to step 102. In step 102, it is determined whether there is an LPP signal at a predetermined position. If there is no LPP signal at the predetermined position (Y), the process proceeds to step 103, where it is determined that Sref is high (H), and the information is sent to the processor. (N) when the signal is transmitted to the (CPU) 16 and the LPP signal is present at the predetermined position (N), the process proceeds to step 104. Proceeds to step 105, determining that Sref is low (L), and transmits the determination information to the processor 16.

  The processor (CPU) 16 fetches the information a plurality of times, determines whether the state is partially abnormal due to the influence of a scratch or the like, or whether the state is such a state on average, and determines that adjustment is necessary. For example, when it is determined to be H, the DC voltage output from the D / A converter 23 is controlled to be low, and when it is determined to be L, the DC voltage output from the D / A converter 23 is controlled to be high. Then, the quality of the pre-pit signal is evaluated again. This process is repeated until the evaluation is OK.

  In this embodiment, the evaluation result of the pre-pit decoder 26 can be used. That is, the pre-pit signal is composed of a set of 3-bit signals including a sync signal, indicates one address in one ECC block area of the recording signal, decodes the pre-pit signal into an address signal, and performs address detection. By performing error correction in the error correction unit, a more accurate address signal can be obtained. Similarly, the error state of the address signal is accumulated a plurality of times, and it is determined that the error signal is not in an error range such as a scratch, and the threshold value can be similarly controlled. However, in this case, it takes time for one ECC block to obtain the address signal, and the adjustment requires a longer processing time than the method described above.

  Further, in this embodiment, when a disc is inserted, the type of the disc is determined, and when the type of the disc is determined to be DVD-R or DVD-RW, this adjustment is performed for each disc. Since the noise component due to the leakage of the RF signal is significantly different between the area where the signal is recorded on the disc and the area where the signal is not recorded, the threshold value is switched for each of the components in the reproducing amplifier. The processor 16 detects an RF ENV signal obtained by detecting the envelope signal of the RF signal that has been detected, and sets a threshold value when the disc is inserted for each of the case where the signal is present and the case where the signal is not present. In the case where the adjustment is made and this adjustment value is stored, and recording is performed in that area, the stored threshold value is output based on the address position and the optimum value is output. Control to. As a result, accurate pre-pit detection can be performed.

  Further, in this embodiment, in particular, the noise component due to the leakage of the RF signal is significantly different between when the signal is recorded on the disc and when the signal is being reproduced. Is set by the processor 16 in response to a recording / reproduction switching timing signal, and the threshold value is adjusted at the time of recording and reproduction at the time of insertion of the disc, and stored based on the address position. The set threshold value is output and controlled to an optimum value. As a result, accurate pre-pit detection can be performed. During recording on the DVD-RW, the pre-pit signal and the wobble signal are amplitude-modulated by the erasing power and the recording power, but a signal sampled by the erasing power by a sample and hold circuit (not shown) may be used. Recording conditions (such as an optimum recording power for DVD-R, an optimum recording power and an erasing power value for DVD-RW) which are conditions for recording on the disk as LPP information of the inner peripheral portion of the disk are recorded. ing. In the case of performing recording, as a first step, this power value is read when a disc is inserted, and in a second step, the optimum power at that time is recorded before recording, and the power calibration area on the inner circumference or the data of the data in the case of DVD-RW is recorded. Trial writing is performed in the recording area, an optimum value is detected, and the threshold value Sref is set based on the recording power or the erasing power value of the optimum value. The LPP signal can be detected in a short time.

  As a result, an address signal can be obtained based on a pre-pit detection signal with high accuracy, and accurate recording / reproduction control and rotation control of DVD-R and DVD-RW can be performed.

  In the present embodiment, the case where the position superimposed on the wobbling signal of the pre-pit signal is the maximum amplitude position of the wobbling signal has been described, but the present invention is not limited to this, and the present invention is not limited to this. The present invention is also applicable to a case where a pre-pit signal is superimposed on a position. In this case, the maximum amplitude position of the synchronization signal may be set to the superposition position of the pre-pit signal. Specifically, the phase of the synchronization signal may be shifted based on the phase position of the pre-pit with respect to the wobbling frequency which is known in advance.

  In this embodiment, the case where the present invention is applied to the DVD-R and the DVD-RW has been described. However, the present invention is not limited to this, and information for recording control is recorded by wobbling tracks. The present invention can be widely applied to the case where predetermined digital information is recorded on a recording medium (for example, a tape-shaped recording medium).

  Next, a description will be given of a second embodiment of the information recording apparatus according to the present invention, by referring to FIGS. The second embodiment is for maximizing the quality of a wobbling signal and a reproduction signal of a pre-pit signal in order to perform recording at a higher density than the first embodiment, and will be described in the first embodiment. 3 corresponds to FIG. 9, FIG. 4 corresponds to FIG. 10, and FIG. 6 corresponds to FIG. 11. Other than that, the description is omitted because it is the same as the first embodiment. In the following description, an embodiment in which the present invention is applied to an information recording apparatus for recording digital information transmitted from a host computer on a DVD-Rl will be described.

  The overall configuration and operation of the information recording apparatus according to the present embodiment will be described with reference to FIG. In the following description of the embodiment, the DVD-R1 is pre-formed with the pre-pits 4 including the address information and the like on the DVD-R1 and the wobbled groove tracks 2. When recording digital information, the pre-pits 4 are used. Is detected in advance to obtain address information on the DVD-R1, thereby detecting and recording a recording position on the DVD-R1 where digital information is to be recorded.

  The information recording apparatus S shown in FIG. 9 includes a pickup (reproducing) unit, a pickup 10 as a recording unit, a reproducing amplifier 11, a decoder 12, a pre-pit signal decoder 13, a spindle motor 14 as a rotating unit, Servo circuit 15 as control means, processor (CPU) 16, encoder 17, power control circuit 18, laser drive circuit 19, interface 20, wobbling signal extraction unit 22, BPF 27, X as information extraction means It is composed of a double amplifier 33 and a 1 / X double amplifier 35. Further, digital information SRR to be recorded is input from the external host computer 21 to the information recording device S via the interface 20.

  Next, the overall operation will be described. The pickup 10 combines a laser diode (not shown), a deflection beam splitter, an objective lens, a photodetector, and the like, irradiates a light beam B to the information recording surface of the DVD-Rl based on the laser drive signal SDL, and Based on the radial push-pull method, the wobbling frequency of the bripit 4 and the groove track 2 is detected to record digital information SRR to be recorded, and when there is already recorded digital information, the light beam B The already recorded digital information is detected based on the reflected light.

  Then, the reproduction amplifier 11 amplifies the detection signal SDT including the information corresponding to the pre-pit 4 output from the pickup 10 and the wobbling frequency of the groove track 2, and corresponds to the pre-pit 4 and the wobbling frequency of the groove track 2. The pre-recording information signal SPP is output, and the amplified signal SP corresponding to the already recorded digital information is output.

  Thereafter, the decoder 12 decodes the amplified signal SP by performing 8-16 demodulation and deinterleaving on the amplified signal SP, and outputs a demodulated signal SDM and a servo demodulated signal SSD.

  The pre-recording information signal SPP output from the reproduction amplifier 11 is input to the wobbling signal extraction unit 22 after being amplified by X times by the X-times amplifier 33. The pre-recording information signal SPP output from the reproduction amplifier 11 is also input to the pre-pit signal decoder 13. The reproduction amplifier 11 has an RF ENV detection unit for extracting an RF signal component in a recorded reproduction signal and detecting the RF signal level. When an RF signal is present in the reproduction area, the RF ENV signal obtained from the RF ENV signal is It is supplied to the processor 16.

  The pre-pit signal decoder 13 extracts only a signal obtained by detecting the pre-pit 4 from the pre-recording information signal SPP, outputs a pre-pit detection signal SPDT, decodes this, and decodes the corresponding demodulated pre-pit signal SPD into the CPU 16. Output to

  Further, the wobbling signal extraction unit 22 extracts only the wobbling frequency of the groove track 2 matched with the pre-recording information signal SPP, supplies the extracted signal SDTT to a BPF (Band Pass Filter) 27, and After the removal, the signal is supplied to the servo circuit 15 and the extracted signal SDTT is amplified about 1 / X by the 1 / X amplifier 35 (the signal amplified by X times by the X amplifier 33 is amplified by the 1 / X amplifier). At 35, the signal is amplified by a factor of 1 / X, so that the original signal amplitude is returned as X * 1 / X = 1 (X is a positive real number) and output to the pre-pit signal decoder 13. 9 differs from FIG. 3 in that the X-fold amplifier 33 and the 1 / X-fold amplifier 35 are added, and that the BPF 27 is arranged at the subsequent stage of the wobbling signal extraction unit.

The servo circuit 15 outputs a pickup servo signal SSP for performing focus servo control and tracking servo control in the pickup 10 to the pickup 10 based on the pre-pit detection signal SPDT and the servo demodulation signal SSD.
Further, the servo circuit 15 outputs a spindle servo control signal SSS to the spindle motor 14 by using the speed information corresponding to the wobbling frequency f0 included in the extraction signal SDTT supplied from the wobbling signal extraction unit 22, The servo of the rotation of No. 14 is controlled.

  The interface 20 encodes the digital information SRR transmitted from the host computer 21 under the control of the processor (CPU) 16 into the information recording device S by processing the digital information SRR. 17 is output.

  The encoder 17 combines an ECC generator (not shown), an 8-16 modulator, a scrambler, and the like to form an ECC block, which is a unit for performing error correction during reproduction, based on the digital information SRR. Are subjected to interleaving, 8-16 modulation, and scramble processing in a predetermined order to generate a modulation signal SRE and supply it to the power control circuit 18.

  The power control circuit 18 outputs a recording signal SD for controlling the output of a laser diode (not shown) in the pickup I0 to the laser drive circuit 19 based on the modulation signal SRE. The laser drive circuit 19 outputs to the optical pickup 10 a laser drive signal SDL for actually driving the laser diode to emit the light beam B based on the recording signal SD.

  The processor (CPU) 16 acquires the pre-recording information by using the input demodulated pre-pit signal SPD, and obtains the digital information corresponding to the position on the DVD-R1 corresponding to the address information corresponding to the acquired pre-recording information. The operation of recording the SRR is controlled. In parallel with these, the processor 16 outputs a reproduction signal SOT corresponding to the already recorded digital information to the outside based on the demodulated signal SDM, and mainly controls the entire information recording apparatus S.

  The information recording device S can also reproduce the information recorded on the DVD-R1. In this case, the reproduced signal SOT is output to the outside via the processor 16 based on the demodulated signal SDM. Will be done.

  Next, a detailed configuration of the pre-pit signal decoder 13 will be described with reference to FIGS. 5, 7, 10, 11, and 12. FIG. FIG. 10 is a block diagram showing a detailed configuration of the pre-pit signal decoder 13 of FIG. In FIG. 10, the BPF 27, the wobbling signal extractor 22, the X-multiplier amplifier 33, the 1 / X-multiplier amplifier 35, and the servo circuit 15 are also illustrated in order to explain the input signal to the pre-pit signal decoder 13. .

  As shown in FIG. 10, the pre-pit signal decoder 13 is supplied with a digital signal of a predetermined level (value) set by the processor (CPU) 16, converts the digital signal into a digital-to-analog signal, and outputs the digital signal. A threshold setting unit that amplifies the signal SDTT of the wobbling signal extraction unit 22 to about 1 / X times by the 1 / X amplifier 35 and adds the signal Sph from the peak hold circuit unit 34 that holds the peak to set the threshold Sref. 23, a comparator 25 as detection means, an LPP and sync detection unit 36, and a decoder 26.

The pre-recording information signal SPP input to the X-fold amplifier 33 has, for example, a waveform including a pre-pit signal larger than the signal amplitude of the wobbling signal with respect to a sine-wave wobbling signal as shown in FIG. is there. Moreover, while the originally required pre-pit signal is superimposed on the sine wave peak position of the wobbling signal in the upward direction, the originally unnecessary pre-pit signal is superimposed downward on the sine wave of the wobbling signal. . In particular, since the originally unnecessary pre-pit signal is not synchronized with the wobbling signal, if the wobbling signal is binarized in the subsequent stage with the center voltage, it becomes a periodic component noise. There is. For this reason, in the first embodiment, the pre-pit signal component is intended to be removed by the BPF. However, if such a BPF is arranged at this position, the pre-pit signal passes through the BPF, so that a periodic fluctuation occurs in the wobbling signal. In addition, as described later, when the envelope signal of the wobbling signal for extracting the pre-pit signal is generated and compared with the pre-pit signal, the phase may be shifted from the delay when passing through the BPF.
Therefore, it is necessary to perform a wobbling signal without passing through the BPF. The wobbling signal extraction unit 22 is constituted by, for example, an amplitude limiter as shown in FIG. This LPF is an LPF from which a wobbling signal can be extracted. The signal after passing through the LPF is compared with the original signal, and both amplitude directions of the original signal are limited by a voltage of about 0.7 V corresponding to a forward voltage drop of a diode. When the input signal 1 and the input signal 2 having a larger amplitude than the input signal 1 are input, the resultant output signals 1 and 2 clearly have a residual component of the pre-pit signal component of 2 with respect to the wobbling signal component. In other words, it is advantageous that the amplitude of the input signal is larger. In order to input a large amplitude signal to the wobbling signal extraction unit 22 as described above, it is necessary to increase the amplitude of the Spp signal at the preceding stage. For example, in a configuration where the circuit requires low power consumption, Is 3 V, when the dynamic range of the signal is 2 V, and when the amplitude of the pre-pit signal is about 1: 3 with respect to the amplitude of the wobbling signal as shown in FIG. Is passed to the comparator 25, the amplitude of the wobbling signal becomes 0.5 V, which indicates that the effect of the diode is low. Therefore, in the present invention, the Spp signal is multiplied by X (for example, 4 times) and input to the wobbling signal extraction unit 22 with the amplitude of the wobbling signal set to (for example, 2 V) as shown in FIG. Then, as shown in FIG. 11E, the pre-pit signal component is largely removed as shown in FIG. 11C, and the signal multiplied by X is multiplied by 1 / X (for example, 1/4) to obtain the signal shown in FIG. In this case, the amplitude of the original signal is set to be the same, and the comparator 25 compares the amplitudes.

  As described above, the wobbling signal extraction unit 22 includes a limiter including a diode and the like as shown in FIG. 12, an LPF, and the like. A wobbling frequency component is further extracted from the extracted signal SDTT as shown in C) by the BPF 27 and output to the servo circuit 15.

  For example, as shown in detail in FIG. 5, the servo circuit 15 includes a VCO (Voltage controlled oscillator) 270, a frequency divider (1 / N) 28, a multiplier 29, an amplifier 30, an LPF (Low Pass Filter). The BPF 32 comprises a PLL (Phase Locked Loop) circuit and a binarized PLL signal SPL in synchronization with the extracted wobbling signal SDTT. As shown in FIG. 11D, the PLL signal SPL has the same phase and the same frequency as the extracted wobbling signal SDTT.

  Note that, as described above, since the normal prepits 4 are previously arranged at predetermined phase positions with respect to the groove track 2, the positions superimposed on the wobbling signal SPP are also constant.

  Accordingly, as described above, the PLL signal SPL output from the servo circuit 15 is compared with the pre-recording information signal SPP and the predetermined threshold Sref, and a signal SPDT obtained as a signal equal to or higher than the threshold Sref is described later with reference to FIG. By comparing with the sync detection LPP 36 shown in (1), a more accurate pre-pit detection signal can be obtained.

  However, as shown in FIG. 11 (A), the amplitude of the wobbling signal fluctuates due to interference with an adjacent track in addition to the frequency component corresponding to the wobbling frequency of the groove track 2 and the pre-recording information signal SPP is recorded. When a signal is reproduced or recorded, a high frequency component which is a noise due to a difference in erasing power or recording power or a write strategy signal is included. In addition, DVD-R and DVD-RW, and versions 1.0 and 1.1 among them. , 2.0, 2.1, etc., and the high-frequency noise component greatly fluctuates due to variations in the disc or pickup, so that the level difference between the pre-pit portion and other portions becomes small, and the predetermined threshold value which is a fixed It is difficult to detect the pre-pit signal with high accuracy in the method of comparing with.

  The signal SDTT of the wobbling signal extraction unit 22 shown in FIG. 10 is amplified to 1 / X by the 1 / X amplifier 35 (FIG. 11 (E)), and after returning to the original signal amplitude, has a predetermined discharge time constant. A signal obtained by adding a DC value from the D / A converter 23 set by the processor (CPU) 16 to the signal Sph (FIG. 11F) from the peak hold circuit unit 34 for performing peak hold in FIG. Sref.

  Although FIG. 10 shows a configuration including the peak hold circuit unit 34, the peak hold circuit unit 34 is not an essential component, and directly supplies the output signal SDTT of the wobbling signal extraction unit 22 to the threshold setting unit 24. It is also possible.

  As can be seen from the relationship between the signals, the wobbling signal to be compared with the original signal Spp passes through the respective circuits of the X-multiplier amplifier 33 and the 1 / X-multiplier amplifier 35 to minimize the influence of the pre-pit signal. Since the amplitude is the same as that of the original signal and does not pass through the BPF 27 as in the first embodiment, for example, even if the linear velocity of the disk changes, the phase of the original signal is shifted. No problem occurs. In FIG. 11A, the amplitude of the pre-pit signal is about three times the amplitude of the wobbling signal, but this amplitude is obtained when the information signal to be recorded on the disk is not recorded. When a signal has already been recorded or is being recorded, the amplitude of the pre-pit signal fluctuates greatly, and it is only about the signal amplitude in FIG. It is. Also in this case, in this circuit configuration, the wobbling signal to be compared with the original signal passes through the respective circuits of the X-multiplier amplifier 33 and the 1 / X-multiplier amplifier 35 to minimize the influence of the pre-pit signal. Therefore, since the amplitude is the same as that of the original signal and does not pass through the BPF 27 having the steep passing characteristic as in the first embodiment, even if the linear velocity of the disk changes, the difference between the original signal and Since a problem such as a significant shift in phase does not occur, the wobble signal without the pre-pit signal of the original signal can be faithfully compared as an envelope signal in the peak hold circuit 34, so that the pre-pit which is a position signal and a timing signal is used. Signals can be accurately extracted. Also, in order to extract a wobbling signal, the signal passes through the circuit of the X-times amplifier 33 to minimize the influence of the pre-pit signal, and passes through the BPF 27 to generate a wobbling signal. Therefore, an accurate frequency signal is generated. be able to.

  The amplitude value of the wobbling signal, which is the output signal of the peak hold circuit unit 34, is input to the A / D converter of the processor (CPU) 16, and the D / A conversion is performed based on the A / D converted value of the amplitude value. The configuration is such that the output of the device 23 can be adjusted. In this case, it is possible to easily adjust even if the amplitude value of the wobble signal or the noise signal superimposed on the wobble signal has a difference in level.

  As shown in FIG. 11 (G), FIG. 11 (H) shows a case where the comparator 25 compares the Sref signal for extracting the pre-pit signal with the Sref signal. FIG. 11 (I) shows the case where the comparison is performed at 25, and FIG. 11 (J) shows the case where the comparison is performed by the comparator 25 using the Sref2 signal. FIG. 11H shows a case where the pre-pit signal is normally extracted. FIG. 11 (I) and FIG. 11 (J) show the case where the amplitude of the LPP fluctuates depending on the case. It can be seen that the signal becomes abnormal.

  Therefore, the threshold value for comparing the pre-recording information signal SPP is configured to be variably set as described above, and the quality of the pre-pit detection obtained by comparing the threshold value and the pre-recording information signal SPP is optimized. , More accurate pre-pit detection becomes possible.

  The PLL signal SPL as the synchronization signal used for the amplitude modulation of the present embodiment has the same phase as the pre-recording information signal SPP.

  Therefore, by detecting the sync signal of the pre-pit signal and generating the gate of the address signal and the interpolation signal by the LPP and sync detector 36, the comparator SPDT is gated in the H section of the PLL signal SPL. Thus, a more accurate pre-pit signal can be obtained. The pre-pit signal thus obtained may be any of the signals shown in FIG. 11H, FIG. 11I, or FIG. 11J depending on the threshold. Therefore, as shown in FIG. 7, the LPP and sync detector 36 detects whether a pre-pit (LPP) signal can be obtained at a predetermined interval timing during the wobble window (Sph section) (step 100), and If a signal is obtained (Y), the current process is determined to be appropriate, and the determination information is transmitted to the processor (CPU) 16 (step 101). If not (N), the process proceeds to step 102. In step 102, it is determined whether there is an LPP signal at a predetermined position. If there is no LPP signal at the predetermined position (Y), the process proceeds to step 103, where it is determined that Sref is high (H), and the information is sent to the processor. (N) when the signal is transmitted to the (CPU) 16 and the LPP signal is present at the predetermined position (N), the process proceeds to step 104, and when two or more LPP signals are obtained at the predetermined position (Y), Proceeds to step 105, determining that Sref is low (L), and transmits the determination information to the processor 16. Here, the number of LPP signals obtained in a predetermined time is counted, but when counting is not performed, for example, it is detected whether or not a pre-pit (LPP) signal can be obtained at predetermined intervals (step 100). Then, if it is obtained, it is determined as OK, and if it is not obtained, Sref is determined to be H or L, and while the output of the D / A converter 23 is gradually changed to the value on the L side or H side, each D / A The best Sref voltage can be obtained by detecting whether or not a pre-pit (LPP) signal can be obtained at a predetermined interval timing based on the value of the A converter 23 and repeating this until it becomes OK.

  The processor (CPU) 16 fetches these pieces of information a plurality of times, and determines whether or not it is in such a state on average to thereby evaluate whether or not the state is partially abnormal due to the influence of a scratch or the like.

In this embodiment, the evaluation result of the pre-pit decoder 26 can be used. That is, the pre-pit signal is composed of a set of 3-bit signals including a sync signal, indicates one address in one ECC block area of the recording signal, decodes the pre-pit signal into an address signal, and performs address detection. By performing error correction in the error correction unit, a more accurate address signal can be obtained. Similarly, the error state of the address signal is accumulated a plurality of times, and it is determined that the error signal is not in an error range such as a scratch, and the threshold value can be similarly controlled. However, in this case, it takes time for one ECC block to obtain an address signal, and a longer processing time is required to complete the adjustment than in the method described above.

  In this embodiment, when a disc is inserted, the type of the disc is determined, and when the type of the disc is determined to be DVD-R or DVD-RW, the value of Sref, which is the initial value, is set in advance depending on the type of disc. This value is read out and set in a nonvolatile memory. As a result, the adjustment time can be reduced. In addition, this adjustment is performed for each disk. In particular, the noise component due to the leakage of the RF signal is significantly different between an area where the signal is recorded on the disk and an area where the signal is not recorded. The processor 16 detects an RF ENV signal obtained by detecting the envelope signal of the RF signal formed in the regenerative amplifier so as to switch the threshold with respect to the signal. The threshold value is adjusted when the disc is inserted, and the adjusted value is stored for each of the cases where the disk is not inserted. When the recording is performed in the area, the threshold value stored based on the address position is stored. Is output and controlled to the optimum value. As a result, accurate pre-pit detection can be performed.

  Further, in this embodiment, in particular, the noise component due to the leakage of the RF signal is significantly different between when the signal is recorded on the disc and when the signal is being reproduced. Is set by the processor 16 in response to a recording / reproduction switching timing signal, and the threshold value is adjusted at the time of recording and reproduction at the time of insertion of the disc, and stored based on the address position. The set threshold value is output and controlled to an optimum value.

  As a result, accurate pre-pit detection can be performed. During recording on the DVD-RW, the pre-pit signal and the wobble signal are amplitude-modulated by the erasing power and the recording power, but a signal sampled by the erasing power by a sample and hold circuit (not shown) may be used. Recording conditions (such as an optimum recording power for DVD-R, an optimum recording power and an erasing power value for DVD-RW) which are conditions for recording on the disk as LPP information of the inner peripheral portion of the disk are recorded. ing. In the case of performing recording, as a first step, this power value is read when a disc is inserted, and in a second step, the optimum power at that time is recorded before recording, and the power calibration area on the inner circumference or the data of the data in the case of DVD-RW is recorded. Trial writing is performed in the recording area, an optimum value is detected, and the threshold value Sref is set based on the recording power or the erasing power value of the optimum value. The LPP signal can be detected in a short time. That is, if the recording power or the erasing power value is different, the amplitude of the wobble and the pre-pit signal during recording or erasing is different, but with a certain correlation therewith, the amplitude of the signal superimposed on these signals is also different. For example, a value proportional to the power value may be added to the output voltage.

  As a result, an address signal can be obtained based on a pre-pit detection signal with high accuracy, and accurate recording / reproduction control and rotation control of DVD-R and DVD-RW can be performed.

  In the present embodiment, the case where the position superimposed on the wobbling signal of the pre-pit signal is the maximum amplitude position of the wobbling signal has been described, but the present invention is not limited to this, and the present invention is not limited to this. The present invention is also applicable to a case where a pre-pit signal is superimposed on a position. In this case, the maximum amplitude position of the synchronization signal may be set to the superposition position of the pre-pit signal. Specifically, the phase of the synchronization signal may be shifted based on the phase position of the pre-pit with respect to the wobbling frequency which is known in advance.

  In this embodiment, the case where the present invention is applied to the DVD-R and the DVD-RW has been described. However, the present invention is not limited to this, and information for recording control is recorded by wobbling tracks. The present invention can be widely applied to the case where predetermined digital information is recorded on a recording medium (for example, a tape-shaped recording medium).

FIG. 1 is a perspective view illustrating an example of a configuration of a DVD-R and a DVD-RW according to an embodiment. FIG. 3 is a diagram illustrating an example of a recording format in a DVD-R and a DVD-RW according to an embodiment. FIG. 2 is a block diagram illustrating a schematic configuration of the information recording apparatus according to the first embodiment. FIG. 3 is a block diagram illustrating a detailed configuration and the like of a pre-pit signal decoder according to the first embodiment. FIG. 5 is a block diagram illustrating a detailed configuration of a servo circuit that outputs a synchronization signal to the pre-pit signal decoder of FIG. 4. FIG. 5 is a diagram illustrating signal waveforms at main points in the pre-pit signal decoder according to the first embodiment. 5 is a flowchart of an LPP and sync detection unit according to the embodiment. FIG. 7 is a diagram showing waveforms of a reproduction signal and a gate signal for explaining a conventional prepit signal detection method. It is a block diagram showing a schematic structure of an information recording device of a 2nd example. FIG. 11 is a block diagram illustrating a detailed configuration and the like of a pre-pit signal decoder according to a second embodiment. FIG. 10 is a diagram illustrating signal waveforms at main points in a pre-pit signal decoder according to a second embodiment. FIG. 11 is a diagram illustrating a detailed configuration and a signal waveform of a wobbling signal extraction unit according to a second embodiment.

Explanation of reference numerals

1 ... DVD-R
2. Groove track 3 Land track 4 Prepit 5 Dye film 6 Gold deposition surface 7 Protective layer 10 Pickup 11 Reproduction amplifier 12 Decoder 13 Pre-pit signal decoder 14 Spindle motor 15 Servo circuit 16 Processor 17 Encoder 18 Power control circuit 19 Laser drive circuit 20 Inter Phase 21 Host computer 22 Wobbling signal extraction unit 23 D / A converter
24: threshold setting unit 25: comparator 26: decoder 27: BPF
33 X-fold amplifier 34 Peak hold circuit 35 1 / X-fold amplifier 36 LPP and sync detector B Light beam S Information recording device SP Optical bot SPP Pre-recording information signal SPDT Pre-pit detection signal SPD Demodulated pre-pit detection signal SDTT Extraction signal SPL PLL signal Sref Reference signal SRR Digital information SD ... Recording signal SDT ... Detection signal SDL ... Laser drive signal SOT ... Reproduction signal SP ... Amplification signal SDM ... Demodulation signal SSD ... Servo demodulation signal SPN ... Demodulation pre-pit signal SSP: Pickup servo signal SSS: Spindle servo control signal SDD: Defect detection signal

Claims (8)

The information track is wobbled and recorded at a frequency related to a reference clock for controlling the rotation of the recording medium, and a prepit having a predetermined phase relationship with the wobbled information track and having sync information and data information is formed. A pre-pit detection device that detects the pre-pit when recording information on a recording medium,
Pickup means for simultaneously irradiating the information track and an adjacent track adjacent to the information track with a light beam, and outputting a signal based on reflected light of the light beam from the information track and the adjacent track,
Wobbling signal extraction means for extracting the wobbling signal component from an output signal of the pickup means,
Reference signal generating means for generating a reference signal having a signal level variably controlled according to a control signal,
Pre-pit signal extraction means for comparing the wobbling signal with the reference signal and extracting a pre-pit signal component corresponding to the pre-pit;
Evaluation means for evaluating the presence of a pre-pit signal component corresponding to the pre-pit of the sync information among the pre-pit signal components corresponding to the extracted pre-pit,
And a reference signal control means for generating a control signal for variably controlling the signal level of the reference signal in accordance with the evaluation result of the evaluation means and supplying the control signal to the reference signal generation means. apparatus.   The pre-pit detection device according to claim 1, wherein the reference signal is a signal obtained by superimposing a DC voltage of a predetermined value based on the extracted wobbling signal.   3. The pre-pit detection device according to claim 1, wherein the reference signal is switched during reproduction without a signal, during reproduction of a recorded area, and during recording. The information track is wobbled and recorded at a frequency related to a reference clock for controlling the rotation of the recording medium, and a prepit having a predetermined phase relationship with the wobbled information track and having sync information and data information is formed. For a recording medium that is, a pre-pit detection method for detecting the pre-pit when recording information,
Simultaneously irradiating the information track and an adjacent track adjacent to the information track with a light beam, and outputting a detection signal based on reflected light of the light beam from the information track and the adjacent track,
Extracting a wobbling signal for extracting the wobbling signal component from the detection signal;
Generating a reference signal whose signal level is variably controlled according to the control signal;
Extracting the pre-pit signal component corresponding to the pre-pit by comparing the wobbling signal and the reference signal;
Evaluating the presence of a pre-pit signal component corresponding to the pre-pit of the sync information among the pre-pit signal components corresponding to the extracted pre-pit,
Generating a control signal for variably controlling the signal level of the reference signal in accordance with the evaluation result.   5. The method according to claim 4, wherein the reference signal is a signal obtained by superimposing a DC voltage having a predetermined value based on the extracted wobbling signal.   6. The pre-pit detection method according to claim 4, wherein said reference signal comprises a step of switching during reproduction without a signal, during reproduction of a recorded area, and during recording.   3. The pre-pit detection device according to claim 1, wherein the reference signal is switched according to a recording power value or an erasing power value during recording. 6. The pre-pit detection method according to claim 4, wherein the reference signal is switched according to a recording power value or an erasing power value during recording.

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