JP2005115989A - Demodulation method, demodulation apparatus, and information recording medium device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform phase demodulation by an optimum setting, even if a phase comparison signal for the largest phase demodulation level deviates. <P>SOLUTION: Phase adjustment circuits 24, 51 generate a signal (sinusoidal wave) in which the phase of a wobbling signal is variably adjusted by "α", and a phase comparison signal (cosine wave) in which the phase of the wobbling signal is varied by (90°+α). The multiplication processing for the wobbling signal and the sinusoidal wave is made by a multiplier 20, and the phase of a carrier outputted by a carrier generation circuit 18 is demodulated. The multiplication processing of the wobbling signal and the phase comparison signal is made by a multiplier 52. A control section 55 controls the variable adjustment value "α" of the phase by the phase adjustment circuits 24, 51, based on a value (sinusoidal wave), based on the result of the multiplication of the multiplier 52 and information (value m) for indicating the phase difference between a signal, based on the result of multiplication processing by a multiplier 20, when the level of phase demodulation is the largest and the wobbling signal that are stored in a storage circuit 54. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a demodulation device and method for detecting and demodulating a carrier wave signal from a wobbling signal read from the information recording medium, and an information recording medium device provided with the demodulation device.

  In the technique disclosed in Patent Document 1, a carrier wave and a wobbling signal are detected from separate detection systems from the detection signal from the optical disc, and the phase difference between the carrier wave and the wobbling signal is detected, and the carrier wave is set so as to eliminate this phase difference. The timing of the detection result is adjusted so that the demodulation performance is good.

  FIG. 10 is a configuration diagram of a basic demodulation circuit of the technique of Patent Document 1. In FIG. This demodulation circuit generates a carrier wave including a band limiting filter such as a BPF (band pass filter) 116 for removing noise and phase modulation components from a wobbling signal and a PLL (Phase Locked Loop) 117 for generating a stable signal. A circuit 118 is used to generate a carrier signal. On the other hand, the wobbling signal is passed through an LPF (low-pass filter) 119 in order to remove only noise components, and the multiplier 120 performs multiplication with the carrier signal. Then, the phase demodulation information for detecting the phase shift is obtained by inputting the output signal from the multiplier 120 to the integrator 122 and the like.

  In addition, a phase adjustment circuit 124 is added to detect a phase shift between the generated carrier wave signal and the wobbling signal by the carrier wave generation circuit 118. The BPF 116 that removes noise components and phase modulation components included in the wobbling signal is likely to change in phase depending on the frequency. For this reason, a phase difference occurs between a carrier wave signal generated from a signal that has passed through the BPF 116 and a wobbling signal that has passed through only the LPF 119 with little phase change. Therefore, the phase adjustment circuit 124 generates a phase comparison signal that is 90 ° different in phase from the carrier wave signal. Assuming that the carrier wave signal is a sine wave (sine wave), the phase comparison signal is a cos wave (cosine wave). When the phase comparison signal and the wobbling signal that has passed through the LPF 119 are multiplied by the multiplier 120, a signal that changes in accordance with α of the phase shift (90 + α) ° between the two is obtained from the multiplication result. This α phase shift is the same as the phase shift between the generated carrier wave signal and the wobbling signal.

  For detecting the phase difference between the carrier wave and the wobbling signal, as described above, a phase difference comparison signal having a 90 ° phase difference from the wobbling signal is generated from the detection result of the carrier wave, and multiplication of the phase difference comparison signal and the wobbling signal is performed. When the integration result is zero when the integration period is n periods (n: positive integer), the demodulation performance is most improved. To do.

JP 2001-126413 A

  FIG. 11 shows a relationship when there is no phase difference between the wobble ring (WBL) signal and the phase comparison signal when the above-described demodulation circuit is used. From the phase comparison signal, it is possible to output a signal (cos wave) whose phase is 90 ° different from the signal (sin wave) having the same phase as the carrier wave part of the WBL signal, and the phase of each signal can be finely adjusted.

  FIG. 12 shows the output result of the multiplier 120 when the signal shown in FIG. 11 is input to the multiplier 120. When the phase comparison signal is a sine wave, the output of the multiplier 120 is a signal having a frequency twice that of the WBL signal or the phase comparison signal, and the DC level becomes a positive level when the WBL signal has no phase inversion. It becomes a negative level in the inversion part. Therefore, phase demodulation can be performed by detecting the level of the output signal of multiplier 120. In order to detect the DC level, the output signal can be obtained by integrating the output signal for an integral multiple of one period. FIG. 13 shows the output signal of the integrator 122 for that purpose, and the integration period is one period of the original signal.

  On the other hand, when the phase comparison signal is a cosine wave, the output of the multiplier 120 is as shown in FIG. 11, and the DC level is always zero in both the carrier part and the phase inversion part of the WBL signal. As a result, when the output result of the multiplier 120 is input to the integrator 122, the result obtained by integrating the output signal for one period of the original signal is zero.

  However, this relationship is lost when there is a phase difference between the WBL signal and the phase comparison signal. That is, when the output level of the integrator 122 when there is a phase difference between the phase comparison signal and the WBL signal is calculated, it changes as shown in FIG. That is, in the case of calculating a sine wave, the demodulation level is the highest when there is no phase difference, and the integration result of the signal subjected to the calculation of the cosine wave is zero when there is no phase difference.

  In the technique disclosed in Patent Document 1, this property is utilized, and the phase of the phase comparison signal is adjusted so that the integration result of the cosine wave operation becomes zero, so that the PM demodulation level is maximized and stabilized. PM demodulation is possible.

  However, when adjustment is actually performed by calculating the cosine wave, the phase adjustment value that maximizes the phase demodulation performance may be slightly different from the phase adjustment value obtained by cos conversion. FIG. 15 shows the result of the actually calculated sin wave calculation and the result of the cosine wave calculation. In the graph of FIG. 15, the vertical axis corresponds to the detection level detected by the integrator 122, and the horizontal axis corresponds to the phase adjusted by the phase adjustment circuit 124. As can be seen from FIG. 15, the value of the phase that zero-crosses the cosine wave calculation (# 80 waveform) is slightly different from the phase value that maximizes the sine wave calculation (# 00 waveform). . This may be caused by the influence of waveform distortion or the like caused by a circuit such as a WBL detection circuit for detecting a WBL signal or a carrier wave generation circuit 118.

  An object of the present invention is to make it possible to perform phase demodulation with an optimum setting even if a shift occurs in the phase comparison signal when the phase demodulation level becomes maximum.

  The present invention relates to a carrier wave detecting step for detecting a carrier wave signal from a wobbling signal detected from an information recording medium, a signal in which the phase of the wobbling signal is variably adjusted, and a phase comparison signal in which the phase of the signal is further adjusted to a predetermined degree An adjustment step of generating a carrier wave, a first multiplication step of performing a phase demodulation of the carrier wave by performing a multiplication process of the wobbling signal and a signal variably adjusted in phase, and the wobbling signal and the phase comparison signal Based on a second multiplication step for performing a multiplication process, a value based on the result of the multiplication in the second multiplication step, and a result of the multiplication process in the first multiplication step when the level of the phase demodulation is maximized The adjustment means based on the information stored in the storage means storing the information indicating the phase difference between the signal and the wobbling signal And a control step of controlling a variable adjustment value of the phase with a comprising at demodulation method.

  Another aspect of the present invention provides carrier detection means for detecting a carrier signal from a wobbling signal detected from an information recording medium, a signal in which the phase of the wobbling signal is variably adjusted, and the phase of the signal is further predetermined. Adjusting means for generating a phase comparison signal adjusted to some extent; first multiplying means for performing phase demodulation of the carrier wave by performing multiplication processing of the wobbling signal and a signal whose phase is variably adjusted; and the wobbling signal; A phase difference between a wobbling signal and a second multiplication means for performing multiplication processing with the phase comparison signal; and a signal based on a result of the multiplication processing by the first multiplication means when the level of the phase demodulation is maximized Storage means for storing information indicating, a value based on the result of multiplication of the second multiplication means, and information stored in the storage means Based on a by and demodulating device and a control unit for controlling the adjustment value of the variable of the phase by the adjustment means.

  Therefore, even if a shift occurs in the phase comparison signal when the phase demodulation level becomes the highest, the result of the multiplication process by the first multiplication step and the first multiplication means when the phase demodulation level becomes the highest in advance is obtained. Information indicating the phase difference between the base signal and the wobbling signal is stored, and the phase difference resulting from the multiplication processing by the first multiplication step and the first multiplication means is adjusted, so that demodulation can be performed in good condition. it can.

  The best mode for carrying out the present invention will be described.

  FIG. 1 is a block diagram showing a schematic configuration of an optical disc apparatus 1 that implements the information recording medium apparatus of the present invention. This optical disc apparatus 1 includes a spindle motor 61 for rotating and driving an optical disc 15 as an optical recording medium, an optical pickup device 23, a laser control circuit 62, an encoder 25, a motor driver 27, an analog signal processing circuit 28, a decoder 31, a servo. A controller 33, a buffer RAM 34, a D / A converter 36, a buffer manager 37, an interface 38, a ROM 39, a CPU 40, a RAM 41, and the like are provided. Note that the arrows in FIG. 1 indicate the flow of typical signals and information, and do not represent the entire connection relationship of each block. In this embodiment, a DVD is used as an example of the optical disk 15.

  The optical pickup device 23 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 15 and guides a return light beam reflected by the recording surface to a predetermined light receiving position. A light receiver that receives the returned light beam at the light receiving position and a predetermined drive system (focusing actuator, tracking actuator, seek motor, etc.) (all not shown in FIG. 1) and the like are incorporated.

  As an example, as shown in FIG. 2A, the light receiver includes a four-divided light receiving element 80 (a first light receiving element 80a, a second light receiving element 80b, a third light receiving element 80c, and a fourth light receiving element 80d). ). In FIG. 2A, 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 light receiving element 80a and the second light receiving element 80b has the same rectangular shape with the long side in the horizontal direction (Y-axis direction) in FIG. 2A. The third light receiving element 80c and the fourth light receiving element 80d have the same rectangular shape with the long side in the vertical direction (X-axis direction) in FIG. 2A. A second light receiving element 80b is arranged in contact with the first light receiving element 80a on the lower side (-X side) in FIG. 2A of the first light receiving element 80a. A fourth light receiving element 80d is disposed on the left side (-Y side) of the third light receiving element 80c in FIG. 2A in contact with the third light receiving element 80c.

  As shown in FIG. 2B, the reflected light RB from the recording surface of the optical disc 15 is branched in two directions by the prism 85 that constitutes the optical system of the optical pickup device 23, and is one reflected light that has passed through the prism 85. RB1 is applied to the first light receiving element 80a and the second light receiving element 80b. The other reflected light RB2 branched in the −X direction by the prism 85 is further bent in the traveling direction in the + Z direction by the reflecting mirror 86, and is irradiated to the third light receiving element 80c and the fourth light receiving element 80d.

  Here, as shown in FIG. 3 (a), out of the reflected light RB, the reflected light RBa on the upper side of the paper in FIG. 3 (a) is irradiated to the first light receiving element 80a, and the lower side of the paper in FIG. 3 (a). Side reflected light RBb is applied to the second light receiving element 80b. Further, as shown in FIG. 3B, the reflected light RBc on the right side of the paper in FIG. 3B of the reflected light RB is irradiated to the third light receiving element 80c, and on the left side of the paper in FIG. 3B. The reflected light RBd is applied to the fourth light receiving element 80d. Each of the light receiving elements 80a to 80d performs photoelectric conversion, and outputs a current (current signal) corresponding to the amount of received light to the analog signal processing circuit 28 (FIG. 1) as a photoelectric conversion signal.

  The light receiver is not limited to the four-divided light receiving element 80. For example, a two-divided light receiving element including a first light receiving element 80a and a second light receiving element 80b, a third light receiving element 80c, and the like. You may comprise from the 2 division | segmentation light receiving element containing the 4th light receiving element 80d. Further, four light receiving elements may be arranged in parallel. Furthermore, the shape and arrangement of each light receiving element are not limited to the present embodiment.

  Returning to FIG. 1, the analog signal processing circuit 28 includes an I / V amplifier (current-voltage conversion amplifier) unit 81 that converts current signals, which are output signals of the light receiving elements 80 a to 80 d of the optical pickup device 23, into voltage signals, and wobbling. A wobbling signal detection circuit 30 for detecting a signal, an RF signal detection circuit 82 for detecting an RF signal including reproduction information, and an error signal detection circuit 83 for detecting an error signal such as a focus error signal or a track error signal. Yes.

  As shown in FIG. 4, the I / V amplifier 81 includes a first I / V amplifier 81a that converts a current signal from the first light receiving element 80a into a voltage signal (signal Sa), and a second light receiving element. A second I / V amplifier 81b that converts the current signal from 80b into a voltage signal (signal Sb), and a third I / V that converts the current signal from the third light receiving element 80c into a voltage signal (signal Sc). A V amplifier 81c and a fourth I / V amplifier 81d that converts a current signal from the fourth light receiving element 80d into a voltage signal (signal Sd). In the RF signal detection circuit 82, the signal Sa and the signal Sb The signal Sc and the signal Sd are added, and the addition result is further binarized and detected as an RF signal.

  The error signal detection circuit 83 obtains a difference between the signal Sa and the signal Sb, further binarizes the result, and detects it as a focus error signal. Further, the difference between the signal Sc and the signal Sd is obtained, and the result is further binarized and detected as a track error signal. The detected focus error signal and track error signal are output from the error signal detection circuit 83 to the servo controller 33, respectively.

  The wobbling signal detection circuit 30 detects a wobbling signal from the signals Sc and Sd and outputs it to the decoder 31.

  The decoder 31 extracts address information, a synchronization signal, and the like from the ADIP information included in the wobbling signal detected by the wobbling signal detection circuit 30. The address information extracted here is output to the CPU 40, and the synchronization signal is output from the decoder 31 to the encoder 25. The decoder 31 performs reproduction processing such as demodulation and error correction processing on the RF signal detected by the RF signal detection circuit 82. Furthermore, when the playback data is other than music data (for example, image data, document data, etc.), the decoder 31 performs error check and error correction processing based on the check code added to the data, and passes through the buffer manager 37. Stored in the buffer RAM 34. The decoder 31 includes a demodulator 2 (FIG. 5 and later), which will be described later, and details of its circuit configuration and operation will be described later.

  The servo controller 33 creates a control signal for controlling the focusing actuator of the optical pickup device 23 based on the focus error signal detected by the error signal detection circuit 83 and outputs the control signal to the motor driver 27. The servo controller 33 creates a control signal for controlling the tracking actuator of the optical pickup device 23 based on the track error signal detected by the error signal detection circuit 83 and outputs the control signal to the motor driver 27.

  When the data recorded on the optical disc 15 is music data, the D / A converter 36 converts the output signal of the decoder 31 into analog data, and outputs it as an audio signal to an audio device or the like.

  The buffer manager 37 manages the accumulation of data in the buffer RAM 34 and notifies the CPU 40 when the accumulated data amount reaches a predetermined value.

  The motor driver 27 drives the focusing actuator and tracking actuator of the optical pickup device 23 based on the control signal from the servo controller 33. Further, the motor driver 27 controls the spindle motor 61 based on an instruction from the CPU 40 so that the linear velocity of the optical disk 15 is constant (CLV) or the rotation speed is constant (CAV). Further, the motor driver 27 drives a seek motor of the optical pickup device 23 based on an instruction from the CPU 40 to control the position of the optical pickup device 23 in the sledge direction (radial direction of the optical disk 15).

  The encoder 25 adds an error correction code to the data stored in the buffer RAM 34 and creates data to be written to the optical disc 15. Then, based on an instruction from the CPU 40, write data is output to the laser control circuit 62 in synchronization with the synchronization signal from the decoder 31. The laser control circuit 62 controls the output of the semiconductor laser of the optical pickup device 23 based on the write data from the encoder 25. The laser control circuit 62 outputs a timing signal synchronized with the mark recording period and the space recording period to the wobbling signal detection circuit 30 during recording.

  The interface 38 is a bidirectional communication interface that communicates with an external host (for example, a personal computer), and conforms to a standard interface such as ATAPI (ATAttachment Packet Interface) or SCSI (Small Computer System Interface).

  The CPU 40 controls the operation of each unit according to a program stored in the ROM 39 and temporarily stores data necessary for the control in the RAM 41.

  FIG. 5 is a circuit diagram of the demodulator 2 provided in the decoder 31 for implementing the demodulator of the present invention. This demodulator 2 includes a band limiting filter such as a BPF (band pass filter) 16 and a PLL for generating a stable signal in order to remove noise and phase modulation components from the wobbling signal detected by the wobbling signal detection circuit 30. A carrier wave signal is generated using a carrier wave generation circuit (carrier wave detection means) 18 comprising (Phase Locked Loop) 17. On the other hand, the wobbling signal is passed through an LPF (low-pass filter) 19 in order to remove only noise components, and a multiplier (first multiplication means) 20 performs multiplication with the carrier signal. Then, the phase demodulation information for detecting the phase shift is obtained by inputting the output signal from the multiplier 20 to the integrator 22 or the like.

  In the demodulating circuit of Patent Document 1 described above, a phase adjustment circuit (adjustment unit, first phase adjustment unit) 24 is used to detect a phase shift between the generated carrier wave signal and the wobbling signal by the carrier wave generation circuit 18. Is added. That is, the phase of the BPF 16 that removes noise components and phase modulation components included in the wobbling signal is likely to change depending on the frequency. For this reason, a phase difference occurs between the carrier signal generated from the signal that has passed through the BPF 16 and the wobbling signal that has passed through only the LPF 19 having a small phase change. Therefore, the phase adjustment circuit 24 generates a phase comparison signal that is 90 ° out of phase with the carrier signal. Assuming that the carrier wave signal is a sine wave (sine wave), the phase comparison signal is a cos wave (cosine wave). When this phase comparison signal and the wobbling signal that has passed through the LPF 19 are multiplied by the multiplier 20, a signal that changes in accordance with α of the phase shift (90 + α) ° between the two is obtained from the multiplication result. This phase shift of α is the same as the phase shift between the generated carrier signal and the wobbling signal.

  In such a circuit, it is possible to output a signal (cos wave) whose phase is 90 ° different from a signal (sin wave) having the same phase as the carrier wave part of the wobbling signal from the phase comparison signal.

  However, when the problem described in the problem to be solved by the above-described invention occurs, that is, as shown in FIG. 6, the phase value at which the cosine wave zero-crosses and the phase value at which the sine wave is maximized are slightly shifted. (In this example, the phase difference a), the demodulator 2 performs the following means.

  That is, in the example of FIG. 6, the value (voltage) b of the cos wave output from the integrator 22 when the phase difference is a is stored, and thereafter the phase difference is adjusted so that the value of the cos wave becomes b. By doing so, the integral output (= PM demodulation level) at the time of calculating the sine wave is always maximized so that the phase difference setting can be set optimally.

  Therefore, in the demodulating device 2 of FIG. 5, the phase adjustment circuit 24 generates and outputs a signal having a different α ° phase as a sin wave with respect to the carrier signal from the carrier generation circuit 18. Here, “α” is a phase adjustment value. Further, a phase adjustment circuit 51 (adjustment means, second phase adjustment means) is provided separately from the phase adjustment circuit 24, and a signal having a phase difference of (90 + α) ° with respect to the carrier wave signal from the carrier wave generation circuit 18 is set as a cosine wave. Generate and output. Again, “α” is a phase adjustment value.

  The multiplier 20 multiplies the sin wave output from the phase adjustment circuit 24 and the wobbling signal that has passed through the LPF 19. The multiplier (second multiplication means) 52 multiplies the cosine wave output from the phase adjustment circuit 51 and the wobbling signal that has passed through the LPF 19. The integrator (first integration means) 21 integrates the output of the multiplier 20 for one period of the carrier wave, and the integrator (second integration means) 53 integrates the output of the multiplier 52 with one period of the carrier wave. Integrate in minutes.

  The storage circuit (storage means) 54 stores a digital value m corresponding to the value b of the cosine wave output from the integrator 22 when the phase difference a is described above. The D / A converter 56 D / A converts the digital value m stored in the storage circuit 54 and converts it to the voltage value b described above. The control unit 55 adjusts the phase of the phase adjustment circuits 51 and 24, that is, the value of the phase adjustment value α described above, based on the output Iout (voltage) of the integrator 53 and the voltage value b after D / A conversion. Do.

  With such a circuit configuration, the output output from the integrator 53 corresponds to the cosine wave in FIG. 6, and the output output from the integrator 21 corresponds to the sine wave in FIG. Then, in the storage circuit 54, an integrated output value (value b in FIG. 6) when the sin wave is calculated in advance to calculate the cosine wave when the integrated output is maximized is obtained, and the storage circuit 54 corresponds to the value b. The value m to be stored is stored. For each optical disc apparatus 1 as an individual product, the value m may be obtained at the time of adjustment before shipment and stored in the storage circuit 54 or may be adjusted at the time of mounting. The method of doing is also considered.

  As shown in FIG. 6, the value of the phase at which the cosine wave crosses zero is different from the value of the phase that maximizes the sine wave (phase difference a). When the output is b, the control unit (control unit) 55 performs, for example, the following control.

  If Iout> b, the phase adjustment value α is set in the positive direction by a predetermined value g.

  If Iout = b, the phase adjustment value α is not changed.

  If Iout <b, the phase adjustment value α is set in the minus direction by a predetermined value g.

  By performing such control, the level of the cosine wave output from the integrator 53 is automatically adjusted to b (note that feedback control is performed only for a value proportional to the difference between Iout and b. You may do it.) Therefore, since the integrated output level of the cosine wave is not 0, but b, the output of the integrator 22 of the sin wave, that is, the level of the demodulated data is adjusted from FIG.

  Another circuit configuration example of the demodulator 2 will be described.

  First, in a recording medium such as DVD + RW / R, the phase modulation section to be demodulated is a part of a wobbling signal (only 8 periods out of 93 periods in the case of DVD + RW / + R) as shown in FIG. 8, and the other parts are phase modulated. There is no wobble. Therefore, the phase demodulation (determining and integrating the sin wave) may be performed only for the phase modulation section.

  Therefore, the phase adjustment operation for generating the cosine wave and the phase demodulation operation for generating the sine wave can be temporally divided. For example, the rectangular wave signal sig_a shown in FIG. 8 may be generated, the phase adjustment operation may be performed in this H level section, and the phase demodulation operation may be performed in the L level section. The sig_a signal can be generated by counting the wobbling signal if the synchronization of the wobbling signal can be detected.

  FIG. 7 shows a circuit configuration example for realizing the above means. In the demodulator 2 of FIG. 7, the same circuit elements as those of the demodulator 2 of FIG. 7 is replaced with a multiplier 52, an integrator 53, phase adjustment circuits 24 and 51, and a control unit 55, instead of a phase adjustment circuit (adjustment unit) 60, a control unit (control unit) 61, and a timing generation unit. (Timing generating means) 62 is provided.

  The timing generation unit 62 is a circuit that generates the signal sig_a in FIG. 8 by acquiring synchronization information of the wobbling signal and counting the wobbling signal. The phase adjustment circuit 60 is a circuit that can select whether to output a signal having the same phase as the carrier wave or to output a signal having a phase shifted by 90 ° from the carrier wave according to the input signal sig_a. This can be adjusted in phase by the signal (sig_b) output from the control unit 61 as in the above-described phase adjustment circuits 51 and 24. The phase adjustment circuit 60 outputs (corrects) a signal (cos wave) that is 90 ° out of phase when the signal sig_a is at the H level, and outputs a signal (sin wave) that does not have a phase shift when the signal sig_a is at the L level. (demodulation).

  The control unit 61 performs substantially the same operation as the control unit 55 described above. The difference from the control unit 55 is that the signal sig_b output from the timing generation unit 62 can be switched between output and non-output of the signal sig_b. When the signal sig_b is at the H level, the phase adjustment circuit 60 performs phase adjustment control (correction), and when the signal sig_b is at the L level, the phase adjustment circuit 60 does not perform phase adjustment control (demodulation). Operate. The signals in this case and the timing of the correction / demodulation operation are as shown in FIG.

  According to the demodulating device 2 of FIG. 7, the circuit elements can be reduced and the manufacturing cost can be reduced as compared with the demodulating device 2 of FIG.

  5 and 7, the carrier wave generation circuit 18 detects the carrier wave signal from the wobbling signal detected from the media (carrier wave detection step), and the phase adjustment circuits 24, 51, 60 wobble the signal. A signal (sin wave) in which the phase of the signal is variably adjusted by “α”, and a phase comparison signal (cos wave) in which the phase of the signal is further adjusted to a predetermined degree, in this example, 90 ° are generated (adjustment process). ). Then, the multiplier 20 multiplies the wobbling signal and the sine wave whose phase is variably adjusted to demodulate the phase of the carrier wave (first multiplication step). Further, the multiplication processing of the wobbling signal and the phase comparison signal is performed by the multiplier 52 (or the multiplier 20) (second multiplication step). Then, in the control units 55 and 61, a value (sin wave) based on the result of multiplication in the second multiplication step and a signal based on the result of multiplication processing in the first multiplication step when the level of phase demodulation is the highest. The phase adjustment circuit 24, 51 or the phase adjustment circuit 60 can change the phase based on the information stored in the storage circuit 54 that stores the information (value m) indicating the phase difference between the signal and the wobbling signal. The adjustment value “α” is controlled (control process). As a result, the demodulation method of the present invention can be implemented.

  According to the technical contents described above, even if the phase comparison signal has a deviation when the phase demodulation level is maximized, the phase difference between the sin wave and the wobbling signal when the phase demodulation level is maximized in advance is calculated. Since the indicated information (value m) is stored and the phase difference of the sin wave is adjusted, demodulation can be performed in a good state.

1 is a block diagram showing a schematic configuration of an optical disc apparatus that is the best mode for carrying out the present invention. FIG. It is explanatory drawing of a 4-part dividing light receiving element. It is explanatory drawing of the reflected light in an optical disk. It is explanatory drawing of an I / V amplifier part. It is a circuit diagram of a demodulator. It is explanatory drawing explaining the phase shift | offset | difference of a sin wave and a cosine wave. It is a circuit diagram of another example of composition of a demodulator. It is explanatory drawing which shows the relationship between a wobbling signal and signal sig_a. It is explanatory drawing which shows the relationship between a wobbling signal, signal sig_a, and the output of a phase adjustment circuit. It is a circuit diagram which shows the principal part of the conventional demodulator. It is a timing chart of a wobbling signal, a sine wave, and a cosine wave in a conventional demodulator. It is a timing chart of the output of the multiplier of a sine wave and a cosine wave in the conventional demodulator. It is a timing chart of the output of the integrator of a sine wave and a cosine wave in the conventional demodulator. It is explanatory drawing explaining the relationship of the phase of a sin wave and a cosine wave in the conventional demodulator. It is explanatory drawing explaining the shift | offset | difference of the phase of a sin wave and a cosine wave in the conventional demodulator.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Information recording medium apparatus 2 Demodulator 18 Carrier detection means 20 1st multiplication means 24 Adjustment means, 1st phase adjustment means 51 Adjustment means, 2nd phase adjustment means 52 2nd multiplication means 21 1st integration means 53 Second integration means 54 Storage means 60 Adjustment means 61 Control means 62 Timing generation means

Claims (12)

A carrier wave detection step of detecting a carrier wave signal from a wobbling signal detected from an information recording medium;
An adjustment step of generating a signal in which the phase of the wobbling signal is variably adjusted, and a phase comparison signal in which the phase of the signal is further adjusted to a predetermined degree;
A first multiplication step of performing a phase demodulation of the carrier wave by performing a multiplication process of the wobbling signal and a signal whose phase is variably adjusted;
A second multiplication step for performing multiplication processing of the wobbling signal and the phase comparison signal;
A value based on the result of multiplication in the second multiplication step, and a phase difference between the signal based on the result of multiplication processing in the first multiplication step and the wobbling signal when the level of the phase demodulation is maximized A control step of controlling the variable adjustment value of the phase by the adjustment means based on the information stored in the storage means storing information;
A demodulation method comprising: Carrier wave detection means for detecting a carrier wave signal from a wobbling signal detected from an information recording medium;
A signal that variably adjusts the phase of the wobbling signal, and an adjustment unit that generates a phase comparison signal in which the phase of the signal is further adjusted to a predetermined degree;
First multiplication means for performing phase demodulation of the carrier wave by performing multiplication processing of the wobbling signal and the signal whose phase is variably adjusted;
Second multiplication means for performing multiplication processing of the wobbling signal and the phase comparison signal;
Storage means for storing information indicating a phase difference between a signal based on the result of multiplication processing by the first multiplication means and the wobbling signal when the level of the phase demodulation is maximized;
Control means for controlling the variable adjustment value of the phase by the adjustment means based on a value based on a result of multiplication of the second multiplication means and information stored in the storage means;
A demodulating device. The adjusting means includes
First phase adjusting means for variably adjusting the phase of the carrier wave signal;
Second phase adjusting means for adjusting the phase of the carrier wave signal to a phase different from the phase of the output signal of the first phase adjusting means to be the phase comparison signal;
With
The control means controls the variable adjustment value of the phase by the adjustment means by controlling the adjustment value of the phase by the first and second phase adjustment means,
The demodulator according to claim 2.   The demodulator according to claim 3, wherein the storage unit stores a value based on a result of multiplication of the second multiplication unit when a value based on the multiplication by the first multiplication unit is maximized. First integrating means for integrating the result of multiplication by the first multiplying means;
Second integration means for integrating the result of multiplication by the second multiplication means;
With
The storage means stores the output value of the second integration means as a value based on the result of multiplication of the second multiplication means when the value based on the multiplication by the first multiplication means is maximized. And
The control means is configured to output the phase by the first and second phase adjustment means based on the output result of the second integration means and the output result of the second integration means stored in the storage means. To control the adjustment value of
The demodulator according to claim 4. The first phase adjusting means generates a signal having a phase different from the carrier signal by α as the variable adjustment value,
The second phase adjusting means generates a signal having a phase different from the carrier signal by (90 ° + α) as the phase comparison signal as the phase adjustment,
The control means controls the value of α with the phase adjustment value as α.
The demodulation device according to any one of claims 3 to 5. A signal indicating the timing of the phase modulation part of the wobbling signal and the other part is generated, and when the timing signal indicates the timing of the phase modulation part and when it does not indicate, the adjusting means causes the wobbling signal to have different phases. The phase of the wobbling signal is variably adjusted by phase adjustment when the timing of the phase modulation portion is indicated, and the phase comparison signal is obtained by phase adjustment when the timing of the phase modulation portion is not indicated. Timing generation means,
The control means determines that the timing signal by the phase adjusting means is based on a value based on the result of multiplication of the multiplication means and a value based on the result of multiplication of the multiplication means stored in the storage means. Controlling the variable adjustment value of the phase when indicating the timing of the modulation portion and when not indicating,
The demodulator according to claim 2. The storage means does not indicate the timing of the phase modulation part when the value based on multiplication when the timing signal by the multiplication means indicates the timing of the phase modulation part is maximum. Storage means for storing a value based on the result of the multiplication,
The demodulator according to claim 7, comprising: Integrating means for integrating the result of multiplication by the multiplying means;
The storage means does not indicate the timing of the phase modulation part when the value based on multiplication when the timing signal by the multiplication means indicates the timing of the phase modulation part is maximum. The output value of the integration means is stored as a value based on the result of multiplication at the time,
The control means controls the variable adjustment value of the phase by the phase adjusting means based on the output result of the integrating means and the output result of the integrating means stored in the storage means.
The demodulator according to claim 8. The adjusting means generates a signal having a phase different from the carrier signal by α as the phase adjustment when the timing signal indicates the timing of the phase modulation portion, and the timing signal does not indicate the timing of the phase modulation portion. Sometimes, as the phase adjustment, a signal whose phase is different from the carrier signal by (90 ° + α) is generated as the phase comparison signal
The control means controls the value of α with the variable adjustment value of the phase as α.
The demodulation device according to any one of claims 7 to 9. The carrier wave detection means detects the carrier wave signal by performing band pass filtering.
The demodulation device according to any one of claims 2 to 10. The demodulator according to any one of claims 2 to 11, comprising:
The carrier wave signal is detected from the wobbling signal read from the information recording medium by the demodulator and phase demodulated, and information is recorded on or reproduced from the information recording medium.
Information recording medium device.

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