JP3756917B2 - Optical disc apparatus and information recording method - Google Patents

Description

  The present invention relates to an optical disc apparatus provided with a wobble signal detection circuit and an information recording method.

  Optical discs such as DVD + R and DVD + RW have information tracks that are wobbled (meandered) at a fixed period, and the tracks are spirally formed on the substrate of the optical disc in advance by a phase modulation method (PSK method = Phase Shift Keying). Things are used.

  In order to create ADIP (Address In Pre-groove) information and the like by detecting and creating a wobble signal based on the light receiving signal of a light receiving element such as a DVD + R, DVD + RW, etc. As the wobble signal detection circuit to be provided, a circuit as shown in FIG. 15 is used. The wobble signal detection circuit in the illustrated example shows only the first half until the digital wobble signal and the analog wobble signal are generated based on the voltage signals VA to VD obtained from the respective light receiving element regions of the four-divided light receiving elements.

  First, each of the voltage signals VA to VD is individually sampled and held by the sample and hold circuit (S / H) 100, and VA, VC, VB, and VC are added by the adder 101, and then 0.5 by the multiplier 102. Double processing is performed to calculate 0.5 × (VA + VC) and 0.5 × (VB + VC). Thereafter, the balance AGC circuit 103 balances the amplitude of 0.5 × (VA + VC) and 0.5 × (VB + VC), and the subtractor 104 gives 0.5 × (VA + VC) −0.5 × (VB + VC). An operation is performed and input to the filter circuit 105. The filter circuit 105 includes a BPF path for a digital wobble signal by a BPF (band pass filter) 106, and an HPF + LPF path for an analog wobble signal by an HPF (high pass filter) 107 and an LPF (low pass filter) 108. Consists of. On the output side of the BPF 106, for example, a binarizer 109 using a comparator is provided.

  Here, the problem is variation in the cut-off frequency fc of the LPF 108 part of the HPF + LPF path. The accuracy of the cut-off frequency fc of the LPF 108 is strict, and variations among circuits become conspicuous during mass production. If the cut-off frequency fc varies, the phase of the analog wobble signal also deviates back and forth from the ideal phase (solid line) according to the height as shown in FIG. When recording information on an optical disc such as DVD + RW, the recording start position is set based on the analog wobble signal. Therefore, if the phase of the analog wobble signal is shifted, the recording start position is also optimal as shown in FIG. It will shift from the position.

  In order to solve this problem, for example, according to Patent Document 1, when overwriting a recorded disc, reproduced data from the recorded portion is used as a reference signal to the clock generator. In the area where information is newly recorded, a method has been proposed in which the clock generation signal recorded in the recorded part is switched in advance to match the clock phase and the recording start position is set to the optimum value. .

  As a method other than Patent Document 1, a disk (hereinafter, referred to as a mirror disk) in which a 14T sync frame portion is provided with a 6T mirror portion (a portion that cannot be written and has high reflectivity) is adjusted to an optimum recording position. There is a way. In this adjustment method, 1 ECC (1 recording block of DVD) is recorded on a mirror disk, and after recording, the disk is read to observe the RF signal waveform (see FIG. 18). Then, the optimum recording position is obtained from the phase difference between the center of the 14T part and the center of the mirror part of the RF signal (when the 14T center coincides with the mirror part center, the recording start position is in an optimum state). Thereafter, the recording start position setting parameter (hereinafter referred to as timeset, see FIG. 19) P1, P2, or P3 is set and adjusted in accordance with the phase difference. That is, even if a phase delay occurs in the wobble signal, the recording start position can be optimized by adjusting the timeset.

JP 2000-173055 A

  However, in the case of Patent Document 1, it can be applied only to an optical disc that already has a recording portion. Also, it is good for an optical disc recorded at the correct recording start position, but in the case of an optical disc having a recording part that is not recorded at the correct recording start position, recording may start from the wrong recording start position. become.

  In the latter case, the adjustment method has to use a special disk, which increases the cost. Further, since it is necessary to actually record on a disk and actually reproduce it to check the state of the RF signal, the time required for the adjustment is greatly increased.

  Also, regarding the inside of the filter circuit, for example, if the phase relationship between the analog wobble signal and the digital wobble signal also varies due to variations in the cut-off frequency fc of the LPF, multiplication processing or the like does not work. Appropriate ADIP information cannot be obtained. As a result, the address information and the synchronization signal are also adversely affected.

The invention according to claim 1 is an optical disc apparatus for recording information by irradiating light to an optical disc having an information track wobbled at a constant period, and has a filter circuit for wobbling the information track. An optical disc apparatus comprising a wobble signal detection circuit for detecting a wobble signal based thereon and demodulating ADIP information, a first path through which the wobble signal passes through a band-pass filter, and the wobble signal through a high-pass filter and a low-pass filter A second path that passes through a filter, and detects a phase difference between input and output signals of the first path to which the wobble signal is input and a phase difference between input and output signals of the second path; The phase difference detection means for detecting the phase difference of the signals passing through the first path and the second path in accordance with the detected phase difference. Comprising an adjusting means for adjusting a phase so that, the.

  According to a second aspect of the present invention, in the optical disc apparatus of the first aspect, the amplitude ratio between the input / output signals of the first path to which the wobble signal is input and the amplitude ratio between the input / output signals of the second path. The phase difference detection means detects a phase difference between the input and output signals based on the detected amplitude ratio.

  According to a third aspect of the present invention, in the optical disc apparatus according to the first or second aspect, the phase difference detection means performs a detection operation at every predetermined timing.

  According to a fourth aspect of the present invention, in the optical disc apparatus according to any one of the first to third aspects, the phase difference detection means executes a detection operation when shifting from a reproduction operation to a recording operation in the CAV method.

According to a fifth aspect of the present invention, there is provided a filter circuit for detecting a wobble signal based on the wobbling of the information track that has been wobbled by irradiating the optical disk having the information track wobbled at a constant period and demodulating ADIP information. In an information recording method for recording information on the optical disc using an optical disc apparatus including a wobble signal detection circuit, a first path through which the wobble signal passes through a band pass filter, and the wobble signal as a high pass filter And the filter circuit having the second path passing through the low-pass filter, and the phase difference between the input / output signals of the first path to which the wobble signal is input and the input / output signals of the second path A phase difference detection step for detecting a phase difference between the first phase and the phase difference between the first phase and the phase difference detection step. And a adjustment step of adjusting the phase so as to match the road and the phase of each signal passed through the second path.

  According to a sixth aspect of the present invention, in the information recording method according to the fifth aspect, the amplitude ratio between the input / output signals of the first path to which the wobble signal is input and the input / output signals of the second path. An amplitude ratio detecting step for detecting each of the amplitude ratios is provided, and the phase difference detecting step detects a phase difference between the input and output signals based on the detected amplitude ratio.

  According to a seventh aspect of the present invention, in the information recording method according to the fifth or sixth aspect, the phase difference detection step executes a detection operation at regular intervals.

According to an eighth aspect of the present invention, in the information recording method according to any one of the fifth to seventh aspects, the phase difference detection step executes a detection operation at the time of transition from the reproduction operation to the recording operation in the CAV method. .

The invention according to claim 9 is an optical pickup that irradiates an optical disc having an information track wobbled at a constant period, receives the light reflected by the optical disc, and outputs a received light signal corresponding to the received light amount. A first filter circuit having at least a low-pass filter for removing noise from the wobble signal based on the wobbling of the information track from the received light signal; and a fundamental frequency of the wobble signal based on the wobbling of the information track from the received light signal A second filter circuit that extracts frequency components in the vicinity of the component, a multiplier that multiplies the signal output from the first filter circuit and the signal output from the second filter circuit, and the multiplier A phase adjustment circuit for adjusting a phase difference between two input signals, and a phase adjustment circuit based on an output signal from the multiplier; And an information detection circuit for detecting information included in the wobble signal, wherein the phase difference between the signal output from the first filter circuit and the signal output from the second filter circuit is calculated. And a means for adjusting a phase difference between two signals input to the multiplier by the phase adjustment circuit based on the phase difference acquired by the phase difference acquisition means.

  According to a tenth aspect of the present invention, in the optical disc apparatus according to the ninth aspect, the phase difference acquisition means includes a signal output from the first filter circuit and a signal before being input to the first filter circuit. First phase difference obtaining means for obtaining a phase difference between the second filter circuit and a second phase difference for obtaining a phase difference between the signal output from the second filter circuit and the signal before input to the second filter circuit. Obtaining means.

  According to the present invention, the phase difference between the input and output signals of the bandpass path to which the wobble signal is input and the phase difference between the input and output signals of the paths of the high pass filter and the low pass filter are detected, respectively. Since the phase is adjusted so that the phases of the band-pass filter path and the paths of the high-pass filter and the low-pass filter coincide with each other, ADIP information can be demodulated in an optimum state.

  In particular, by performing these detection / adjustment operations at fixed timings, it is possible to always perform the recording operation from the optimum recording start position without being affected by sudden power supply voltage fluctuations or temperature changes. ADIP information can be demodulated in a safe state. In addition, since the playback speed changes at the time of playback in the CAV (constant angular velocity) system, the frequency of the wobble signal naturally changes and the optimum adjustment value also changes, but the transition from the playback in the CAV system to the recording operation. Sometimes, by performing these detection / adjustment operations, it is possible to perform the recording operation from the optimum recording start position and to demodulate the ADIP information in an optimum state.

The best mode for carrying out the present invention will be described with reference to the drawings . The present embodiment shows an example of application to an optical disc apparatus provided with a wobble signal detection circuit for an optical disc (information recording medium) 1 such as a DVD + RW capable of recording information. As shown in FIG. 1 (a), the optical disc 1 has an information track 2 wobbling (meandering) at a constant period, and the information track 2 has a phase modulation method (as shown in FIG. 1 (b)). The one formed in advance on the substrate of the optical disk 1 by PSK method = Phase Shift Keying) is used. In FIG. 1A, the black portion is an example of the recording mark 3.

  FIG. 2 is a schematic diagram showing a configuration example of the optical disc apparatus 10 of the present embodiment provided with a wobble signal detection circuit. The optical disk apparatus 10 includes a spindle motor 11 for rotating the optical disk 1, an optical pickup apparatus 12, a laser control circuit 13, an encoder 14, a motor driver 15, an analog signal processing circuit 16, a decoder 17, a servo controller 18, and a buffer RAM 19. , D / A converter 20, buffer manager 21, interface 22, ROM 23, CPU 24, RAM 25, and the like. Note that the arrows shown in FIG. 2 indicate the flow of typical signals and information, and do not represent the entire connection relationship of each block.

  The optical pickup device 12 includes a semiconductor laser as a light source, an optical system that guides a light beam emitted from the semiconductor laser to a recording surface of the optical disc 1 and guides a return light beam reflected by the recording surface to a predetermined light receiving position. A light receiving device arranged at a position for receiving the return light beam and a ° drive system (focusing actuator, tracking actuator, seek motor, etc.) (all not shown) are incorporated.

  As shown in FIG. 3A, the light receiver in the optical pickup device 12 includes, for example, a four-divided light receiving element 30 (first to fourth light receiving elements 30a to 30d). In FIG. 3A, for the sake of convenience, the vertical direction of the paper is the X axis direction, the horizontal direction of the paper is the Y axis direction, and the vertical direction of the paper is the Z axis direction. Each of the first and second light receiving elements 30a and 30b has the same rectangular shape having a long side in the horizontal direction (Y-axis direction) in FIG. 3A and the vertical direction (X-axis direction). It is arranged adjacent to. Each of the third and fourth light receiving elements 30c and 30d has the same rectangular shape with the long side in the vertical direction (X-axis direction) in FIG. 3A and the horizontal direction in the paper (Y-axis). In the direction).

  As shown in FIG. 3B, the reflected light RB from the recording surface of the optical disc 1 is branched in two directions by the prism 31 constituting the optical system of the optical pickup device 12, and is one reflected light that has passed through the prism 31. RB1 is applied to the first and second light receiving elements 30a and 30b. The other reflected light RB2 branched in the −X axis direction by the prism 31 is further bent in the traveling direction in the + Z direction by the reflecting mirror 32, and is irradiated to the third and fourth light receiving elements 30c and 30d.

  Here, as shown in FIG. 4A, among the reflected light RB, the reflected light RBa in the upper half of the paper surface in FIG. 4A is irradiated to the first light receiving element 30a, and the reflected light in the lower half of the paper surface. RBb is applied to the second light receiving element 30b. 4B, among the reflected light RB, the reflected light RBc in the right half of the paper surface in FIG. 4B is irradiated to the third light receiving element 30c, and the reflected light RBd in the left half of the paper surface is reflected. Irradiates the fourth light receiving element 30d. Each of the first to fourth light receiving elements 30a to 30d performs photoelectric conversion and outputs a current (current signal) corresponding to the amount of received light to the analog signal processing circuit 16 as a photoelectric conversion signal.

  The light receiver is not limited to the four-divided light receiving element 30, and includes, for example, a two-divided light receiving element configuration including the first and second light receiving elements 30a and 30b, and the third and fourth light receiving elements 30c and 30d. It may be a two-part light receiving element configuration or the like, or may be a configuration in which the first to fourth light receiving elements 30a to 30d are arranged in a line, and is arbitrary including shape, arrangement, and the like.

Returning to FIG. 2 , the analog signal processing circuit 16 includes an I / V amplifier (current-voltage conversion amplifier) 26 that converts a current signal, which is an output signal of the light receiving elements 30 a to 30 d of the optical pickup device 12, into a voltage signal, a wobble signal. A wobble signal detection circuit 27 for detecting the reproduction signal, an RF signal detection circuit 28 for detecting an RF signal including reproduction information, an error signal detection circuit 29 for detecting a focus error signal and a track error signal, and the like.

  As shown in FIG. 5, the I / V amplifier 26 includes I / V amplifiers 26 a to 26 d that convert current signals from the first to fourth light receiving elements 30 a to 30 d into voltage signals (signals Sa to Sd). ing.

  Further, the RF signal detection circuit 28 adds all these voltage signals Sa to Sd, further binarizes the addition result, and detects it as an RF signal.

The error signal detection circuit 29 obtains the difference between the voltage signals S a and S b, binarizes the result, detects it as a focus error signal, obtains the difference between the voltage signals S c and S d, and binarizes the result. And detected as a track error signal. These focus error signal and track error signal detected here are output from the error signal detection circuit 29 to the servo controller 18, respectively.

  The wobble signal detection circuit 27 detects a wobble signal based on the voltage signals Sc and Sd and outputs the wobble signal to the decoder 17. The configuration of the wobble signal detection circuit 27 will be described later.

  In the decoder 17, address information, a synchronization signal, and the like are extracted from ADIP information included in the wobble signal detected by the wobble signal detection circuit 27. The address information extracted here is output to the CPU 24, and the synchronization signal is output to the encoder 14.

  The decoder 17 also performs reproduction processing such as demodulation and error correction processing on the RF signal detected by the RF signal detection circuit 28. Further, when the reproduction data is other than music data (for example, image data, document data, etc.), the decoder 17 performs error check and error correction processing based on the check code added to the data, and passes through the buffer manager 21. And stored in the buffer RAM 19.

  The servo controller 18 creates a control signal for controlling the focusing actuator of the optical pickup device 12 based on the focus error signal detected by the error signal detection circuit 29 and outputs the control signal to the motor driver 15. The servo controller 18 creates a control signal for controlling the tracking actuator of the optical pickup device 12 based on the track error signal detected by the error signal detection circuit 29 and outputs the control signal to the motor driver 15.

In D / A converter 20, data recorded on the optical disc 1 is in the case of music data, converts the output signal of the decoder 17 into analog data, and outputs to the audio equipment or the like and an audio signal.

  The buffer manager 21 manages the accumulation of data in the buffer RAM 19, and notifies the CPU 24 when the accumulated data amount reaches a predetermined value.

  The motor driver 15 drives the focusing actuator and tracking actuator of the optical pickup device 12 based on the control signal from the servo controller 18. Further, the motor driver 15 controls the spindle motor 11 based on an instruction from the CPU 24 so that the optical disc 1 has a constant linear velocity (CLV method) or a constant rotation speed (CAV method). Further, the motor driver 15 drives a seek motor based on an instruction from the CPU 24 to control the position of the optical pickup device 12 in the sledge direction (radial direction of the optical disc 1).

  In the encoder 14, an error correction code is added to the data stored in the buffer RAM 19 to create write data to the optical disk 1. Based on the instruction from the CPU 24, the write data is output to the laser control circuit 13 in synchronization with the synchronization signal from the decoder 17.

  The laser control circuit 13 controls the output of the semiconductor laser in the optical pickup device 12 based on the write data from the encoder 14. The laser control circuit 13 outputs a timing signal synchronized with the mark recording period and the space recording period to the wobble signal detection circuit 27 during recording.

  The interface 22 is a bidirectional communication interface with a host (for example, a personal computer), and conforms to a standard interface such as ATAPI (At Attachment Packet Interface), SCSI (Small Computer System Interface).

  The CPU 24 controls the operation of each unit as described above according to the program stored in the ROM 23 and temporarily stores data necessary for the control in the RAM 25.

  Next, a configuration example of the wobble signal detection circuit 27 and its output side will be described with reference to FIG. First, sample and hold circuits (S / H) 41a and 41b to which voltage signals Sc and Sd from the I / V amplifiers 26c and 26d are inputted are provided, and the S / H 41a and 41b output side after the sample hold. A balance AGC 42 is provided to balance the amplitudes of the voltage signals Sc and Sd. On the output side of the balance AGC 42, there is provided a subtractor 43 for calculating a difference Sc-Sd between the voltage signals Sc and Sd after the sample and hold. A filter circuit 44 is provided on the output side of the subtracter 43. The filter circuit 44 includes a BPF path for a digital wobble signal by a BPF (band pass filter) 45, and an HPF + LPF path for an analog wobble signal by an HPF (high pass filter) 46 and an LPF (low pass filter) 47. Consists of. On the output side of the BPF 45, for example, a binarizer 48 using a comparator is provided. The frequency band that the BPF 45 allows to pass is the frequency of the carrier wave of the wobble signal (the part other than the phase modulation part in the wobble signal), that is, a limited frequency band near the fundamental frequency of the wobble signal. Therefore, the phase modulation component and noise are reduced from the wobble signal by the BPF 45, and it becomes easy to create a signal corresponding to the carrier component of the wobble signal. The signal corresponding to the carrier wave component has a constant frequency when the optical disk 1 is rotated by the CLV method. On the other hand, the signal that has passed through the HPF 46 and the LPF 47 becomes a wobble signal from which a high-frequency noise component and a low-frequency noise component have been removed. Note that the HPF 46 may be omitted when noise can be removed to an allowable range for acquiring ADIP information only by the LPF 47.

  For the digital wobble signal obtained from the binarizer 48, a PLL circuit 49 for stabilizing the cycle and a delay circuit (delay) 50 for timing adjustment are provided in order, and the same as the digital wobble signal. A sine wave generation circuit 51 for generating a phase sine wave (sin wave) is provided.

  On the other hand, an A / D converter 52 for converting an analog wobble signal obtained from the LPF 47 into digital data is provided. A multiplier 53 for multiplying the analog wobble signal A / D converted by the A / D converter 52 and the digital wobble signal converted into a sine wave is provided. An integrator 54 for integrating the multiplication result is provided on the output side of the multiplier 53. The integrator 54 is set to be reset in units of one wobble period by a reset signal from the timing circuit 55 that generates and outputs a timing signal synchronized with the output of the PLL circuit 49 (output of the delay circuit 50).

  An ADIP information detector 57 is provided on the output side of the integrator 54 via a sample hold circuit (S / H) 56.

  A decoder 17 is connected to the ADIP information detector 57. The decoder 17 detects a synchronization signal ADIPsync based on ADIP information (detects phase modulation of the wobble signal), an error correction unit 62 that performs error correction processing, and address information based on ADIP information after error correction. And an address information extraction unit 63 for extraction.

  The synchronization signal ADIPsync detected by the synchronization detector 61 passes through the delay circuit 64 that is a phase adjustment circuit that outputs the input signal with the phase shifted, and is then input to the encoder 14 to be a write timing signal (recording start timing signal). It is used for the generation of The encoder 14 also receives a write command (or read command) from the CPU 24 at a predetermined timing, and the laser control circuit 13 starts a recording operation when a write timing signal is generated in the presence of the write command. Is set to

  In such a configuration, an outline of a signal processing example in the vicinity of the wobble signal detection circuit 27 will be described with reference to a waveform diagram shown in FIG. First, the voltage signals Sc and Sd, which are the outputs of the I / V amplifiers 26c and 26d, are sampled and held by the S / H 41a and 41b, the amplitude balance after the sample and hold is taken by the balance AGC 42, and the subtractor 43 sets the Sc (S / S / S). After H) -Sd (after S / H) is performed. Since the wobble signal WBL = S1 (see FIG. 7A) on the optical disc 1 cannot actually be grasped as it is, the amplitude balance and the Sc (after S / H) -Sd ( (After S / H) is set to the wobble signal WBL = S1 on the medium. The wobble signal WBL = S1 is input to the filter circuit 44. On the other hand, an analog wobble signal S2 as shown in FIG. 7B is generated through the path between the HPF 46 and the LPF 47, and on the other hand, the BPF 45 By passing through the path, a wobble signal S3 as shown in FIG. 7C is generated, and further, binarized by passing through the binarizer 48 and digital wobble as shown in FIG. 7D. Signal S4 is generated.

  The digital wobble signal S4 passes through a PLL circuit 49 for generating a stable signal having a predetermined period, and is delayed by dlyclock by a delay circuit 50 which is a phase adjustment circuit, as shown in FIG. Is input to the sin wave generation circuit 51 as a digital wobble signal S5. The sin wave generating circuit 51 generates a sin wave S6 having the same phase as the digital wobble signal S5 as shown in FIG.

  The analog wobble signal S2 A / D converted by the A / D converter 52 and the digital wobble signal converted to the sin wave S6 are multiplied by the multiplier 53, and the multiplication result as shown in FIG. The signal S7 is integrated by the integrator 54 to obtain an integration result signal S8 as shown in FIG. The integration result signal S8 is sampled and held by the S / H 56 and input to the ADIP information detector 57 as a signal S9 as shown in FIG. The ADIP information detector 57 detects ADIP information S10 including address information and a synchronization signal as shown in FIG. 7 (j) based on the signal S9. In the decoder 17 to which the ADIP information S10 is input, the synchronization detector 61 outputs an ADIP synchronization signal ADIPsync = S11 as shown in FIG. 7 (k). The ADIP synchronization signal ADIPsync = S11 passes through the delay circuit 64, which is a phase adjustment circuit that shifts the phase of the input signal and then outputs the ADIP synchronization signal ADIPsync = S12, and is input to the encoder 14. The encoder 14 creates a write timing signal S13 based on the ADIP synchronization signal ADIPsync = S12, and starts recording by the laser control circuit 13 under an AND condition with the write command S14 from the CPU 24.

  It is assumed that a certain time interval e is taken between the synchronization signal ADIPsync and the write timing signal (for example, 16 wbl cycle = 32T × 15). In addition, the synchronization signal ADIPsync and the write timing signal are L → H → L once every ADIP time (= 93 wbl cycle = 32T × 93), and the phase modulation unit at the head of 1 ADIP time becomes H. (Referred to as # 0 shown in FIG. 7).

  In such an operation, before the filter processing by the filter circuit 44, that is, at the time of the signal S1, there is no phase shift that affects the phase demodulation or the like. However, after the filter processing by the filter circuit 44, for example, due to variations in the cut-off frequency fc of the LPF 47 unit, a shift occurs in the phase of the analog wobble signal, and a shift occurs in the generation timing of the write timing signal S13. There is a possibility that the recording start position will deviate from the optimum position. In FIG. 7B, “a” represents a phase delay caused by the LPF 47.

Therefore, in Reference Example 1 , an adjustment function for adjusting the shift of the recording start position due to the phase shift in the filter circuit 44 to the optimum position is added. Referring to FIG. 8 that shows a part of the wobble signal detection circuit 27, in the reference example 1 , in the filter circuit 44 to which the wobble signal S1 from the optical disk 1 is input, here, the path between the HPF 46 and the LPF 47 A phase comparator 65 is provided as a phase difference detecting means for detecting a phase difference between signals before and after input / output, and is configured to detect a phase difference corresponding to the phase delay a shown in FIG. 7B, for example. ing.

  On the other hand, in the optical disk apparatus 10, a delay circuit (delay) 64 as an adjusting means for appropriately adjusting the phase of the synchronization signal ADIPsync = S11 that affects the timing of the write timing signal S13 includes the synchronization detector 61 and the encoder 14. The delay circuit 64 is configured such that the phase can be arbitrarily adjusted by setting the delay time timeset (recording start position setting parameter) of the delay circuit 64. Here, there is a proportional relationship as shown in FIG. 9 between the phase difference between the signals before and after the input and output of the path between the HPF 46 and the LPF 47 and the delay time timeset. Note that the proportional relationship shown in FIG. 9 can be easily created, for example, by recording a mirror disk in increments of 1 ECC while changing the timeset, and reproducing the portion. The timing of the write timing signal S13 can be optimized by obtaining in advance and adjusting and setting the delay time timeset of the delay circuit 64 in accordance with the phase difference detected by the phase comparator 65.

Here, the details of the recording timing adjustment setting based on the phase difference detected by the phase comparator 65 will be described with reference to FIG. 10 which shows an excerpt of FIG. To do. FIG. 10 is a waveform diagram showing the relationship between the phase delay a in the path between the HPF 46 and the LPF 47 in the filter circuit 44, the delay amount d by the delay circuit 64, and the write timing signal S13. First, the phase of the synchronization signal ADIPsync = S11 by the synchronization detector 61 is delayed by the amount of delay of the phase of the analog wobble signal S2 in the path between the HPF 46 and the LPF 47 = phase delay a. Then, the phase of the synchronization signal ADIPsync = S12 after the delay processing by the delay circuit 64 is delayed by the delay amount d in timeset. Further, it is assumed that the phase relationship between the synchronization signal ADIPsync = S12 and the write timing signal S13 has a difference of a constant interval e. Further, according to the standard, the wobble signal wbl is one block in 93 cycles, and the write start timing is wbl # 14 + 24T (wbl # 14 is a signal in the 15th cycle counted from the phase modulation unit wbl # 0, 1 wobble cycle = 32T). It is stipulated to bring it to the position. Here, 24T is 1T × 24 of the RF signal. For example, if the disk rotation speed is equivalent to 1 time, 1T≈38.5 ns, and if it is equivalent to 2 times, 1T≈19.2 ns, equivalent to 4 times. For example, 1T ≒ 9.6ns, ... As shown in FIG. 7, since the detected wobble signal is delayed by about one cycle with respect to the actual wobble signal on the optical disc 1, recording starts on the optical disc 1 from the position of approximately wbl # 15 + 24T. (# 15 in Fig. 17 etc. means this).

in this case,
a + d + e = wbl16 cycle + 24bit
= 16 × 32T + 24T
If this holds, the write timing signal is in accordance with the standard. Therefore,
d = 16 × 32T + 24T−ae
The delay time timeset may be adjusted and set so that

As described above, according to the reference example 1 , the wobble signal S1 obtained from the information track 2 of the optical disc 1 is input to the input side of the filter circuit 44 in the optical disc apparatus 10, and before and after the input / output of the path between the HPF 46 and the LPF 47 at that time Since the phase difference of the signal is detected by the phase comparator 65 and the delay time timeset of the delay circuit 64 is adjusted according to the detected phase difference, the timing of the write timing signal is optimized. The recording operation can be performed from the optimum recording start position without being affected by the phase shift in the circuit 44. In particular, by performing these detection / adjustment operations at fixed timings, it is possible to always perform the recording operation from the optimum recording start position without being affected by sudden power supply voltage fluctuations or temperature changes. In addition, since the playback speed changes at the time of playback in the CAV (constant angular velocity) system, the frequency of the wobble signal naturally changes and the optimum adjustment value also changes, but the transition from the playback in the CAV system to the recording operation. Sometimes, by performing these detection / adjustment operations, the recording operation can be performed from the optimum recording start position.

In the first reference example , the phase comparator 65 detects the phase difference between the signals before and after the input / output of the HPF 46 + LPF 47 path. However, as another reference example 2 , the signal before and after the input / output of the BPF 45 is detected. The phase difference may be detected, and the delay amount timeset of the delay circuit 64 may be adjusted and set according to the detected phase difference. In this case, the phase of the analog wobble signal is adjusted in accordance with the phase of the digital wobble signal.

In the reference example 1 , the phase difference between the signals before and after the input / output of the filter circuit 44 is directly detected by the phase comparator 65. However, as another reference example 3 , for example, FIG. As shown, the amplitude ratio a ′ (= HPF46 + LPF47 path output amplitude / HPF46 + LPF47 path input amplitude) of the signal before and after the input / output of the HPF46 + LPF47 path when the wobble signal S1 based on the information track 2 is input is an amplitude comparator. (Amplitude ratio detection means) 66 detects the phase difference (phase difference detection means) 67 based on the amplitude ratio a ′, detects the phase difference (phase delay) a, and sets the delay time timeset of the delay circuit 64. You may make it adjust. In this case, the filter characteristic of the LPF 47 is measured in advance, and the relationship between the amplitude ratio and the phase delay corresponding to the filter characteristic is written in the control program, and the phase difference detector 67 uses this relationship to determine the amplitude ratio a. What is necessary is just to obtain | require the phase difference a from '.

An embodiment of the present invention will be described with reference to FIGS. In the present embodiment, the optical disk apparatus 10 is provided with an adjustment function that eliminates the bad demodulation characteristics of ADIP information caused by the phase shift in the filter circuit 44. In FIG. 12, only the relevant portion in the wobble signal detection circuit 27 is extracted and shown.

  In the present embodiment, when the wobble signal S1 acquired based on the wobbling of the information track 2 is input to the filter circuit 44, the phase difference detection for detecting the phase difference a between the signals before and after the HPF 46 + LPF 47 path at that time And a phase difference detector (phase difference detection means) 65b for detecting the phase difference b of the signal before and after the input / output of the BPF 45 path, and a phase difference detector 65a, 65b. Based on the detection result, the delay time dlyclock of the delay circuit 50 as the adjusting means provided in the subsequent stage of the PLL circuit 49 is adjusted so that the phases of both paths coincide with each other.

  FIG. 13 is a waveform showing the relationship between the phase of the wobble signal S1 before filtering, the phase of the analog wobble signal S2 that has passed through the LPF 47, and the phase of the digital wobble signal S3 that has passed through the BPF 45 (before digitization by the binarization circuit 48). FIG. In the HPF46 + LPF47 path, the phase of the analog wobble signal S2 is delayed by a. In the BPF45 path, the phase of the digital wobble signal S3 is delayed by b. Then, before a sin wave digital wobble signal is generated by the sin wave generating circuit 51, a phase delay corresponding to c can be provided by the delay time dlyclock set in the delay circuit 50 (see FIG. 7 and the like). Here, at the time of ADIP demodulation, since the sin wave = S6 and the analog wobble signal S2 are multiplied by the multiplier 53, the higher the amplitude after multiplication, the more the ADIP information can be demodulated. For that purpose, it is necessary that the phase relationship between the sin wave and the analog wobble signal is the same phase.

Therefore,
a = b + c
When the above holds, the phase relationship between the analog wobble signal and the digital wobble signal becomes the same phase, and the most accurate ADIP demodulation is possible. Therefore, based on the detection results of the phase comparators 65a and 65b,
c = a−b
Thus, the delay time dlyclock of the delay circuit 50 may be adjusted.

  As described above, according to the present embodiment, in the optical disc apparatus 10, the path between the HPF 46 and the LPF 47 when the wobble signal S1 acquired based on the wobbling of the information track 2 of the optical disc 1 is input to the filter circuit 44. The phase difference between the signals before and after the input / output and the phase difference between the paths of the BPF 45 are detected by the phase comparators 65a and 65b, respectively. ADIP demodulation can be optimally performed by adjusting the time dlyclock, so that ADIP information can be demodulated in an optimal state.

  In particular, by performing these detection / adjustment operations at fixed timings, it is possible to always demodulate ADIP information in an optimum state without being affected by sudden power supply voltage fluctuations or temperature changes. In addition, since the playback speed changes at the time of playback in the CAV (constant angular velocity) system, the frequency of the wobble signal naturally changes and the optimum adjustment value also changes, but the transition from the playback in the CAV system to the recording operation. Sometimes, by performing these detection / adjustment operations, the ADIP information can be demodulated in an optimum state.

  In this embodiment, the phase difference between the signals before and after the input / output of each path of the filter circuit 44 is directly detected by the phase comparators 65a and 65b. However, as another embodiment, For example, as shown in FIG. 14, the amplitude ratio a ′ of the signals before and after the input / output of the HPF 46 + LPF 47 path when the wobble signal S1 based on the information track 2 is input (= HPF 46 + output amplitude of the LPF 47 path / input amplitude of the HPF 46 + LPF 47 path) ) Is detected by an amplitude comparator (amplitude ratio detecting means) 66a, and a phase difference (phase delay) a is detected by a phase difference detector (phase difference detecting means) 67a based on this amplitude ratio a ', while the BPF 45 path The amplitude ratio b '(= output amplitude of BPF45 path / input amplitude of BPF45 path) is an amplitude comparator (amplitude ratio detecting means). 6b, based on this amplitude ratio b ', a phase difference detector (phase difference detection means) 67b detects a phase difference (phase lag) b, and a = b + c based on these phase differences a and b. As described above, the delay time timeset of the delay circuit 64 may be adjusted. In this case, the filter characteristics of the LPF 47 and the BPF 45 are measured in advance, the relationship between the amplitude ratio and the phase delay corresponding to the filter characteristics is written in the control program, and this relationship is used in the phase difference detectors 67a and 67b. Thus, the phase differences a and b may be obtained from the amplitude ratios a ′ and b ′.

  When the phase delay due to the BPF 45 is b, in FIG. 7 and the like, an example in which the phase delay a on the LPF 47 side is larger than the phase delay b is shown, but not limited thereto, the BPF 45, HPF 46, and LPF 47 Depending on the characteristics, the reverse, that is, the phase delay b may be larger than the phase delay a. In such a case, it is only necessary to shift the phase of the digital wobble signal S4 by a phase delay where c = b−a (that is, a phase advance in this case).

  In the present embodiment, the output signal of the BPF 45 is delayed by the delay circuit 50. However, instead of or in addition to such a configuration, the output signal of the LPF 47 is used as a phase adjustment circuit. The phase may be adjusted by inputting. Alternatively, the phase difference between the output signal of the LPF 47 and the output signal of the BPF 45 may be directly obtained, and the delay time dlyclock of the delay circuit 50 may be adjusted by this phase difference.

It is a schematic explanatory drawing regarding the information track of an optical disk. It is the schematic which shows the structural example of an optical disk apparatus. It is a front view which shows a light receiver structure. It is a side view which shows a light receiver structure. It is a schematic circuit diagram which shows an I / V amplifier structure. It is a block diagram which shows the structural examples, such as a wobble signal detection circuit. It is a wave form diagram which shows the example of the operation signal of each part. It is a schematic block diagram which extracts and shows a part of wobble signal detection circuit. It is a characteristic view which shows the relationship between the phase difference between input-output signals, and delay time. It is a wave form diagram which shows a part of operation signal example. It is a schematic block diagram which shows the structural example of another reference example 3 regarding a phase difference detection system. It is a schematic block diagram which extracts and shows a part of wobble signal detection circuit of one embodiment of this invention. It is a wave form diagram which shows the phase relationship between the related signals. It is a schematic block diagram which extracts and shows a part of wobble signal detection circuit of another embodiment. It is a schematic block diagram which shows the example of a structure of a part of conventional wobble signal detection circuit. It is a wave form diagram which shows the signal characteristic according to the dispersion | variation in the cut-off frequency fc. It is explanatory drawing which shows a mode that a recording start position shifts. It is explanatory drawing which shows the mode of RF signal waveform. It is a wave form diagram which shows the example of adjustment operation.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Information recording medium 2 Information track 10 Optical disk apparatus 44 Filter circuit 45 Band pass filter 46 High pass filter 47 Low pass filter 50 Adjustment means 64 Adjustment means 65, 64a, 65b Phase difference detection means 66, 66a, 66b Amplitude ratio detection Means 67, 67a, 67b Phase difference detecting means

Claims (10)

An optical disk apparatus for recording information by irradiating light to an optical disk having an information track wobbled at a constant cycle, and having a filter circuit to detect a wobble signal based on wobbling of the information track and to detect ADIP In an optical disc apparatus provided with a wobble signal detection circuit for demodulating information,
A first path through which the wobble signal passes through a band pass filter; and a second path through which the wobble signal passes through a high pass filter and a low pass filter;
Phase difference detection means for detecting a phase difference between input / output signals of the first path to which the wobble signal is input and a phase difference between input / output signals of the second path;
Adjusting means for adjusting the phase so that the phases of the signals that have passed through the first path and the second path coincide with each other according to the detected phase difference;
An optical disc apparatus comprising: Amplitude ratio detection means for detecting an amplitude ratio between the input / output signals of the first path to which the wobble signal is input and an amplitude ratio between the input / output signals of the second path;
2. The optical disc apparatus according to claim 1, wherein the phase difference detection means detects a phase difference between the input and output signals based on the detected amplitude ratio.   The optical disk apparatus according to claim 1, wherein the phase difference detection unit executes a detection operation at every predetermined timing.   4. The optical disc apparatus according to claim 1, wherein the phase difference detection unit executes a detection operation when transitioning from a reproduction operation using a CAV method to a recording operation. Optical disc apparatus comprising a wobble signal detection circuit having a filter circuit for detecting a wobble signal based on wobbling of the information track that has been wobbled by irradiating light onto an optical disc having an information track wobbled at a constant period and demodulating ADIP information In an information recording method for recording information on the optical disc using
Using the filter circuit having a first path through which the wobble signal passes through a band pass filter and a second path through which the wobble signal passes through a high pass filter and a low pass filter;
A phase difference detection step of detecting a phase difference between input / output signals of the first path to which the wobble signal is input and a phase difference between input / output signals of the second path;
An adjustment step of adjusting the phase so that the phases of the signals that have passed through the first path and the second path are matched in accordance with the detected phase difference;
An information recording method comprising: An amplitude ratio detecting step of detecting an amplitude ratio between input / output signals of the first path to which the wobble signal is input and an amplitude ratio between input / output signals of the second path;
6. The information recording method according to claim 5, wherein, in the phase difference detection step, a phase difference between each input / output signal is detected based on the detected amplitude ratio.   The information recording method according to claim 5 or 6, wherein the phase difference detection step performs a detection operation at every predetermined timing. The information recording method according to any one of claims 5 to 7, wherein the phase difference detection step performs a detection operation at the time of transition from the reproduction operation to the recording operation in the CAV method. An optical pickup that emits light to an optical disc having an information track wobbled at a constant period, receives the light reflected by the optical disc, and outputs a received light signal according to the received light amount;
A first filter circuit comprising at least a low-pass filter for removing noise from a wobble signal based on wobbling of the information track from the received light signal;
A second filter circuit for extracting a frequency component in the vicinity of a fundamental frequency component of a wobble signal based on wobbling of the information track from the light reception signal;
A multiplier that multiplies the signal output from the first filter circuit by the signal output from the second filter circuit;
An information detection circuit that detects information contained in the wobble signal based on an output signal from the multiplier ,
Phase difference acquisition means for acquiring a phase difference between the signal output from the first filter circuit and the signal output from the second filter circuit;
A phase adjustment circuit for adjusting a phase difference between two signals input to the multiplier based on the phase difference acquired by the phase difference acquisition unit ;
An optical disc apparatus comprising: The phase difference acquisition means includes
First phase difference acquisition means for acquiring a first phase difference between a signal output from the first filter circuit and a signal before being input to the first filter circuit;
Second phase difference acquisition means for acquiring a second phase difference between a signal output from the second filter circuit and a signal before being input to the second filter circuit;
10. The optical disc apparatus according to claim 9, wherein the phase difference is acquired based on the first phase difference and the second phase difference .

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