JP3566961B1 - Demodulation method, demodulation device, and information recording medium device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a phase demodulation to be performed by an optimal setting even if a phase comparison signal at the time when a phase demodulation level becomes maximum has a deviation.
A phase adjusting circuit (24, 51) generates a signal (sin wave) in which the phase of a wobbling signal is variably adjusted by “α” and a phase comparison signal (cos wave) in which the phase is adjusted by (90 ° + α). I do. The multiplier 20 multiplies the wobbling signal by the sine wave to perform phase demodulation of the carrier output from the carrier generator 18. The multiplier 52 multiplies the wobbling signal by the phase comparison signal. The control unit 55 is based on the value (sin wave) based on the result of the multiplication by the multiplier 52 and the result of the multiplication process by the multiplier 20 when the level of the phase demodulation stored in the storage circuit 54 is the highest. Based on the information (value m) indicating the phase difference between the signal and the wobbling signal, the phase adjustment circuits 24 and 51 control the variable adjustment value “α” of the phase.
[Selection diagram] FIG.

Description

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

  According to the technology disclosed in Patent Document 1, a carrier wave and a wobbling signal are respectively detected from detection signals from an optical disc by separate detection systems, and a phase difference between the carrier wave and the wobbling signal is detected. 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 according to the technique of Patent Document 1. This demodulation circuit generates a carrier wave including a band limiting filter such as a band pass filter (BPF) 116 for removing noise and a phase modulation component from the wobbling signal and a PLL (Phase Locked Loop) 117 for generating a stable signal. A carrier signal is generated using circuit 118. On the other hand, the wobbling signal is passed through an LPF (low-pass filter) 119 to remove only a noise component, and a multiplier 120 performs a multiplication operation on the carrier signal. Then, by inputting an output signal from the multiplier 120 to the integrator 122 or the like, phase demodulation information for detecting a phase shift is obtained.

  Further, a phase adjustment circuit 124 is added to detect a phase shift between the carrier signal and the wobbling signal generated by the carrier generation circuit 118. The BPF 116 that removes a noise component and a phase modulation component included in the wobbling signal easily changes its phase depending on the frequency. For this reason, a phase difference occurs between the carrier signal generated from the signal passing through the BPF 116 and the wobbling signal passing only through the LPF 119 having a small phase change. Therefore, the phase adjustment circuit 124 generates a phase comparison signal having a phase different from the carrier signal by 90 °. Assuming that the carrier signal is a sine wave (sine wave), the phase comparison signal has a relationship of a cosine wave (cosine wave). When this phase comparison signal and the wobbling signal passed through the LPF 119 are multiplied by the multiplier 120, a signal that changes according to α of the phase shift (90 + α) ° of both is obtained from the multiplication result. This phase shift α is the same as the phase shift between the generated carrier signal and the wobbling signal.

  To detect the phase difference between the carrier and the wobbling signal, a phase difference comparison signal having a phase difference of 90 ° from the wobbling signal is generated from the detection result of the carrier as described above, and the 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 cycles (n: a positive integer), the best demodulation performance is obtained. Is what you do.

JP 2001-126413 A

  FIG. 11 shows the 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, a signal (sine wave) having the same phase as the carrier part of the WBL signal and a signal (cos wave) different in phase by 90 ° can be output, and the phase of each signal can be finely adjusted.

  FIG. 12 shows an output result of the multiplier 120 when the signal shown in FIG. When the phase comparison signal is a sine wave, the output of the multiplier 120 is a signal having twice the frequency of the WBL signal or the phase comparison signal, and its 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. The DC level can be detected by integrating the output signal for a period that is an integral multiple of one cycle. FIG. 13 shows an output signal of the integrator 122 for that purpose, and the integration period is one cycle 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 wave portion and the phase inversion portion of the WBL signal. As a result, when the output result of the multiplier 120 is input to the integrator 122, the result of integrating the output signal for one cycle of the original signal becomes zero.

  However, if there is a phase difference between the WBL signal and the phase comparison signal, this relationship is broken. That is, when the output level of the integrator 122 is calculated when there is a phase difference between the phase comparison signal and the WBL signal, the output level changes as shown in FIG. In other words, when calculating a sine wave, the demodulation level is the highest when there is no phase difference, and when there is no phase difference, the integration result of the signal on which the cosine wave has been calculated becomes zero.

  In the technology disclosed in Patent Document 1, utilizing this property, the phase of the phase comparison signal is adjusted so that the integration result of the cosine wave operation becomes zero, and the PM demodulation level is stabilized by maximizing the level. PM demodulation is enabled.

  However, when adjustment is actually performed by calculating a cosine wave, the phase adjustment value at which the phase demodulation performance is maximized may be slightly different from the phase adjustment value obtained by the cosine transform. FIG. 15 shows the results of the actually measured sin wave operation and the results of the cosine wave operation. 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 phase value at which the zero crossing is performed in the calculation of the cosine wave (waveform of # 80) and the phase value that maximizes the calculation of the sine wave (waveform of # 00) are slightly different. . This may be caused by the influence of the distortion of the waveform by the WBL detection circuit for detecting the WBL signal or the circuit such as the carrier generation circuit 118.

  An object of the present invention is to enable phase demodulation to be performed with an optimal setting even if a phase comparison signal at the time when the phase demodulation level is maximized is shifted.

  The present invention provides a carrier detection step 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 a phase comparison signal in which the phase of the signal is further adjusted to a predetermined extent. A first multiplying step of performing a multiplication process of the wobbling signal and the signal whose phase has been variably adjusted to demodulate the phase of the carrier, and a step of calculating the phase of the wobbling signal and the phase comparison signal. A second multiplication step for performing the multiplication processing, a value based on the result of the multiplication in the second multiplication step, and a value based on the result of the multiplication processing in the first multiplication step when the level of the phase demodulation is maximized. The adjusting means based on the information stored in the storage means storing information indicating a 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.

  According to another aspect of the present invention, there is provided a carrier detection unit 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 a degree, first multiplying means for performing a multiplication process of the wobbling signal and the signal whose phase is variably adjusted to perform phase demodulation of the carrier wave, and the wobbling signal; Second multiplying means for performing multiplication processing with the phase comparison signal, and a phase difference between the signal based on the result of the multiplication processing by the first multiplication means when the level of the phase demodulation is maximized and the wobbling signal Storage means for storing information indicating the following: a value based on the result of the multiplication by 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 deviation occurs in the phase comparison signal when the phase demodulation level is the highest, the result of the first multiplication step and the multiplication process by the first multiplication means when the phase demodulation level is the highest beforehand Information indicating the phase difference between the base signal and the wobbling signal is stored, and the phase difference resulting from the multiplication process by the first multiplication step and the first multiplication means is adjusted, so that demodulation can be performed in a good state. it can.

  An embodiment of the present invention will be described.

  FIG. 1 is a block diagram showing a schematic configuration of an optical disk device 1 for implementing an information recording medium device of the present invention. The optical disk device 1 includes a spindle motor 61 for rotating and driving the optical disk 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 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 all of the connection relationships between the blocks. In the present 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 receiving device for receiving the return light beam at the light receiving position, a predetermined driving system (a focusing actuator, a tracking actuator, a seek motor, and the like) (all not shown in FIG. 1) and the like are built therein.

  As an example, as shown in FIG. 2A, the light receiver is 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 convenience, the vertical direction of the paper is defined as the X-axis direction, the horizontal direction of the paper is defined as the Y-axis direction, and the vertical direction of the paper is defined as the Z-axis direction. Each of the first light receiving element 80a and the second light receiving element 80b has the same rectangular shape having a long side in the left-right direction (Y-axis direction) in FIG. 2A. Each of the third light receiving element 80c and the fourth light receiving element 80d has the same rectangular shape whose long side is the vertical direction (X-axis direction) in FIG. 2A. Then, a second light receiving element 80b is disposed in contact with the first light receiving element 80a on the lower side (−X side) of the first light receiving element 80a in FIG. A fourth light receiving element 80d is arranged in contact with the third light receiving element 80c on the left side (−Y side) of the third light receiving element 80c in FIG.

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

  Here, as shown in FIG. 3A, of the reflected light RB, the reflected light RBa on the upper side of the paper surface in FIG. 3A is irradiated on the first light receiving element 80a, and the reflected light RBa on the lower side of the paper surface in FIG. The reflected light RBb on the side is irradiated on the second light receiving element 80b. Further, as shown in FIG. 3B, of the reflected light RB, the reflected light RBc on the right side of the drawing in FIG. 3B is irradiated on the third light receiving element 80c, and the reflected light RBc on the left side of the drawing in FIG. The fourth light receiving element 80d is irradiated with the reflected light RBd. 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-segment light receiving element 80. For example, a two-segment light receiving element including a first light receiving element 80a and a second light receiving element 80b, and a third light receiving element 80c And a two-divided light receiving element including the fourth light receiving element 80d. Further, four light receiving elements may be provided 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 for converting a current signal, which is an output signal of the light receiving element 80a to 80d of the optical pickup device 23, into a voltage signal, 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 and a track error signal are provided. I have.

  As shown in FIG. 4, the I / V amplifier unit 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 the second light-receiving element 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). It comprises a V amplifier 81c and a fourth I / V amplifier 81d for converting 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, respectively, and the result of the addition is further binarized and detected as an RF signal.

  The error signal detection circuit 83 calculates the difference between the signal Sa and the signal Sb, binarizes the result, and detects the result as a focus error signal. Further, a 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 focus error signal and the track error signal detected here 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 signal Sc and the signal Sd, and outputs the signal to the decoder 31.

  The decoder 31 extracts address information, a synchronization signal, and the like from ADIP information included in the wobbling signal detected by the wobbling signal detection circuit 30. The extracted address information is output to the CPU 40, and the synchronization signal is output from the decoder 31 to the encoder 25. Then, 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. Further, when the reproduction data is other than music data (for example, image data or document data), the decoder 31 performs an error check and an error correction process based on the check code added to the data. Stored in the buffer RAM 34. The decoder 31 includes a demodulation device 2 (FIG. 5 et seq.), Which 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. Further, 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 disk 15 is music data, the D / A converter 36 converts the output signal of the decoder 31 into analog data and outputs the analog signal to an audio device or the like as an audio signal.

  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 the tracking actuator of the optical pickup device 23 based on a control signal from the servo controller 33. Further, the motor driver 27 controls the spindle motor 61 based on the instruction of 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 the seek motor of the optical pickup device 23 based on an instruction from the CPU 40, and controls 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 to create data to be written on the optical disk 15. Then, based on an instruction from the CPU 40, the write data is output to the laser control circuit 62 in synchronization with a 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. Then, 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 for communicating with an external host (for example, a personal computer), and conforms to a standard interface such as an ATAPI (ATA Attachment Packet Interface) and a SCSI (Small Computer System Interface).

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

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

  In the demodulation circuit of the above-mentioned Patent Document 1, a phase adjustment circuit (adjustment means, first phase adjustment means) 24 is used in order to detect a phase shift between the generated carrier signal and the wobbling signal by the carrier generation circuit 18. Is added. That is, the phase of the BPF 16 that removes a noise component and a phase modulation component included in the wobbling signal easily changes depending on the frequency. For this reason, a phase difference occurs between the carrier signal generated from the signal passing through the BPF 16 and the wobbling signal passing only through the LPF 19 having a small phase change. Therefore, the phase adjustment circuit 24 generates a phase comparison signal having a phase different from the carrier signal by 90 °. Assuming that the carrier signal is a sine wave (sine wave), the phase comparison signal has a relationship of a cosine wave (cosine wave). When the phase comparison signal and the wobbling signal passed through the LPF 19 are multiplied by the multiplier 20, a signal that changes according to 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, a signal (cos wave) having the same phase as the carrier wave portion of the wobbling signal (sin wave) and a phase (cos wave) having a phase difference of 90 ° can be output 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 value of the phase at which the cosine wave crosses zero and the value of the phase at which the sine wave maximizes are slightly shifted. (In this example, the phase difference a), the demodulation device 2 performs the following means.

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

  Therefore, in the demodulation device 2 of FIG. 5, the phase adjustment circuit 24 generates and outputs a signal having a phase different by α ° from the carrier signal from the carrier generation circuit 18 as a sine wave. 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 different from the carrier signal from the carrier generation circuit 18 by (90 + α) ° is used as a cosine wave. Generate and output. Again, “α” is the phase adjustment value.

The multiplier 20 multiplies the sine wave output from the phase adjustment circuit 24 and the wobbling signal that has passed through the LPF 19. The multiplier (second multiplying means) 52 multiplies the cos wave output from the phase adjustment circuit 51 by the wobbling signal passed through the LPF 19. The integrator (first integrating means) 2 2 multiplier output 20 to one period integration of the carrier, the integrator (second integrating means) 53, the first carrier the output of the multiplier 52 Integrate for the period.

  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 at the time of the phase difference a. The D / A converter 56 D / A converts the digital value m stored in the storage circuit 54 and converts the digital value m into the above-described voltage value b. The control unit 55 adjusts the phase of the phase adjustment circuits 51 and 24, that is, the value of the above-described phase adjustment value α, based on the output Iout (voltage) of the integrator 53 and the voltage value b after the D / A conversion. Do.

In such a circuit configuration, the output which is output from the integrator 53 corresponds to the cos wave of FIG. 6, the output outputted from the integrator 2 2 corresponds to the sin wave of FIG. Then, in the storage circuit 54, an integral output value (value b in FIG. 6) obtained by calculating a sine wave in advance and calculating a cosine wave when the integral output is maximized is determined. This value m may be obtained for each optical disk device 1 as an individual product at the time of adjustment before shipment and stored in the storage circuit 54, or may be adjusted at the time of mounting. There are also ways to do this.

  As shown in FIG. 6, the value of the phase at which the cosine wave crosses zero and the value of the phase at which the sine wave is maximized are shifted (phase difference a), and the integrator 53 of the cosine wave when the sine wave is maximized. When the output is b, the control unit (control means) 55 performs, for example, the following control.

  If Iout> b, the phase adjustment value α is set in the plus 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 (the feedback control is performed by a value proportional to the difference between Iout and b). May be.) Accordingly, since the integrated output level of the cosine wave is not 0 but b, the output of the integrator 22 of the sine wave, that is, the level of the demodulated data is adjusted to be maximum from FIG.

  Another circuit configuration example of the demodulation device 2 will be described.

  First, in a recording medium such as a DVD + RW / R, the phase modulation section to be demodulated is a part of the wobbling signal (only 8 out of 93 cycles in the case of DVD + RW / + R) as shown in FIG. There is no wobble. Therefore, phase demodulation (calculating and integrating a sine wave) may be performed only on the phase modulation unit.

  Therefore, the phase adjustment operation for generating a cosine wave and the phase demodulation operation for generating a 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 the 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 an example of a circuit configuration for realizing the above means. In the demodulation device 2 of FIG. 7, the same reference numerals are given to the same circuit elements as those of the demodulation device 2 of FIG. 5, and the detailed description is omitted. The demodulation device 2 of FIG. 7 includes a phase adjustment circuit (adjustment unit) 60, a control unit (control unit) 61, and a timing generation unit instead of the multiplier 52, the integrator 53, the phase adjustment circuits 24 and 51, and the control unit 55. (Timing generation means) 62 is provided.

  The timing generation unit 62 is a circuit that generates the signal sig_a of 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 a signal having a phase shifted by 90 ° from the carrier wave according to the input signal sig_a. In this case, the phase can be adjusted by the signal (sig_b) output from the control unit 61, similarly to the above-described phase adjustment circuits 51 and 24. When the signal sig_a is at the H level, the phase adjustment circuit 60 outputs a signal (cos wave) having a 90 ° phase shift of the carrier signal (correction), and outputs a signal without a phase shift (sine wave) when the signal sig_a is at the L level. (demodulation).

  The control unit 61 performs almost 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 outputting and not outputting the signal sig_b. When the signal sig_b is at the H level, the phase adjustment circuit 60 performs the phase adjustment control (correction). When the signal sig_b is at the L level, the phase adjustment circuit 60 does not perform the phase adjustment control (demodulation). Operate. Each signal in this case and the timing of the correction / demodulation operation are as shown in FIG.

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

As described above, in the demodulator 2 of FIGS. 5 and 7, the carrier signal is detected from the wobbling signal detected from the medium by the carrier generation circuit 18 (carrier detection step), and the carrier is generated by the phase adjustment circuits 24, 51, and 60. A signal (sine 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 by a predetermined degree, in this example, 90 °, are generated (adjustment step). ). Then, the multiplier 20 multiplies the wobbling signal by the sine wave whose phase has been variably adjusted, and performs phase demodulation of the wobbling signal (first multiplication step). Further, the multiplier 52 (or the multiplier 20) performs a multiplication process of the wobbling signal and the phase comparison signal (second multiplication step). Then, in the control units 55 and 61, a signal (sine wave) based on the result of the multiplication in the second multiplication step and a signal based on the result of the multiplication processing in the first multiplication step when the level of the phase demodulation is maximized. The phase adjustment circuit 24, 51 or the phase adjustment circuit 60 changes the phase based on the information stored in the storage circuit 54 storing information (value m) indicating the phase difference between the signal and the wobbling signal. The adjustment value “α” is controlled (control step). Thereby, the demodulation method of the present invention can be performed.

  According to the technical contents described above, even if the phase comparison signal when the phase demodulation level becomes the largest is shifted, the phase difference between the sine wave and the wobbling signal when the phase demodulation level becomes the largest is previously determined. Since the information (value m) is stored and the phase difference of the sine wave is adjusted, demodulation can be performed in a good state.

FIG. 1 is a block diagram showing a schematic configuration of an optical disc device which is one of the best modes for carrying out the present invention. It is explanatory drawing of a four-division light receiving element. FIG. 3 is an explanatory diagram of reflected light on an optical disk. FIG. 3 is an explanatory diagram of an I / V amplifier unit. It is a circuit diagram of a demodulation device. FIG. 4 is an explanatory diagram illustrating a phase shift between a sine wave and a cosine wave. It is a circuit diagram of another configuration example of the demodulation device. FIG. 4 is an explanatory diagram illustrating a relationship between a wobbling signal and a signal sig_a. FIG. 4 is an explanatory diagram illustrating a relationship between a wobbling signal, a signal sig_a, and an output of a phase adjustment circuit. FIG. 10 is a circuit diagram illustrating a main part of a conventional demodulation device. 9 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 the sine wave and the cos wave in the conventional demodulation device. It is a timing chart of the output of the integrator of the sine wave and the cos wave in the conventional demodulator. FIG. 9 is an explanatory diagram illustrating a phase relationship between a sine wave and a cosine wave in a conventional demodulation device. FIG. 9 is an explanatory diagram illustrating a phase shift between a sine wave and a cosine wave in a conventional demodulation device.

Explanation of reference numerals

REFERENCE SIGNS LIST 1 information recording medium device 2 demodulation device 18 carrier detection means 20 first multiplication means 24 adjustment means, first phase adjustment means 51 adjustment means, second phase adjustment means 52 second multiplication means 21 first integration means 53 second integration means 54 storage means 60 adjustment means 61 control means 62 timing generation means

Claims (12)

A carrier detection step of detecting a carrier signal from the wobbling signal detected from the information recording medium,
A signal in which the phase of the carrier signal is variably adjusted, and an adjusting step of generating a phase comparison signal in which the phase of the signal is further adjusted by a predetermined degree;
A first multiplication step of performing a multiplication process of the wobbling signal and a signal whose phase is variably adjusted to output a signal for performing phase demodulation of the wobbling signal ;
A second multiplication step of performing a multiplication process of the wobbling signal and the phase comparison signal;
A phase difference between the value based on the result of the multiplication in the second multiplication step and a signal based on the result of the multiplication processing in the first multiplication step when the level of the phase demodulation is maximized and the wobbling signal are shown. A control step of comparing the information stored in the storage unit storing the information , and controlling a variable adjustment value of the phase in the adjustment step in accordance with the comparison result ;
A demodulation method comprising: Carrier detection means for detecting a carrier signal from the wobbling signal detected from the information recording medium,
A signal in which the phase of the carrier signal is variably adjusted, and adjusting means for generating a phase comparison signal in which the phase of the signal is further adjusted by a predetermined amount;
First multiplying means for performing a multiplication process of the wobbling signal and the signal whose phase is variably adjusted to output a signal for performing phase demodulation of the wobbling signal ;
Second multiplying means for multiplying the wobbling signal and the phase comparison signal;
Storage means for storing information indicating a phase difference between the signal based on the result of the multiplication processing by the first multiplication means and the wobbling signal when the level of the phase demodulation is highest;
Control means for controlling a variable adjustment value of the phase by the adjustment means in accordance with a result of comparing a value based on the result of the multiplication by the second multiplication means with information stored in the storage means;
A demodulator comprising: The adjusting means,
First phase adjusting means for variably adjusting the phase of the carrier signal;
A second phase adjusting unit that adjusts the phase of the carrier signal to a phase different from the phase of the output signal of the first phase adjusting unit to be the phase comparison signal;
With
The control means controls a 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 demodulation device according to claim 2. 4. The storage unit according to claim 3, wherein the storage unit stores, as the information , a value based on a result of the multiplication by the second multiplication unit when the value based on the multiplication by the first multiplication unit is maximum. Demodulator. First integration means for integrating the result of the multiplication by the first multiplication means;
Second integration means for integrating the result of the multiplication by the second multiplication means;
With
The storage means stores an output value of the second integration means as a value based on a result of the multiplication by the second multiplication means when a value based on the multiplication by the first multiplication means becomes maximum. hand,
The control means controls the phase by the first and second phase adjusting means based on an output result of the second integration means and an output result of the second integration means stored in the storage means. Control the adjustment value of
The demodulation device according to claim 4. The first phase adjustment unit generates a signal having a phase different from the carrier signal by α as the variable adjustment value,
The second phase adjustment unit 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 claim 3. Carrier detection means for detecting a carrier signal from a wobbling signal having a phase modulation unit and other parts detected from the information recording medium,
And timing generating means for generating a timing signal indicating the timing of the phase modulation part and the other part of the wobbling signal,
A signal in which the phase of the carrier signal is variably adjusted, and a phase comparison signal in which the phase of the signal is further adjusted by a predetermined amount, wherein the carrier signal is generated when the timing signal indicates the timing of the phase modulation unit. An adjusting unit that outputs a signal in which the phase of the signal is variably adjusted, and outputs the phase comparison signal when the timing of the phase modulation unit is not indicated,
Multiplication means for performing a multiplication process of the wobbling signal and a signal output from the adjustment means, and outputting a signal for performing phase demodulation of the wobbling signal when indicating the timing of the phase modulation section;
Information indicating the phase difference between the signal based on the result of the multiplication process by the multiplication means and the wobbling signal when the timing signal indicates the timing of the phase modulation section when the level of the phase demodulation is the highest is stored. Storage means,
When the timing signal does not indicate the timing of the phase modulation unit, a value based on the result of the multiplication by the multiplication unit is compared with a value based on the result of the multiplication by the multiplication unit stored in the storage unit. Control means for controlling a variable adjustment value of the phase by the adjustment means,
A demodulation device comprising: The storage means is configured such that when the value based on the multiplication when the timing signal by the multiplication means indicates the timing of the phase modulation section as the information is the maximum, the timing signal by the multiplication means is the timing of the phase modulation section. Storage means for storing a value based on the result of the multiplication when not indicating
The demodulation device according to claim 7, comprising: An integrating means for integrating a result of the multiplication by the multiplying means,
The storage means does not indicate the timing of the phase modulation unit when the value based on the multiplication when the timing signal by the multiplication means indicates the timing of the phase modulation unit is maximum. The output value of the integrating means is stored as a value based on the result of the multiplication at the time,
It said control means based on the output result of said integrating means is stored in the output and the storage means of said integrating means, to control the adjustment value of the variable of the phase due to prior Sulfur butterfly integer unit,
The demodulation device according to claim 8. It said adjustment means, said timing signal generates a different signal of said carrier wave signal and α by a phase as the phase adjustment when showing the timing of the phase modulation unit, the timing signal does not indicate the timing of the phase modulation part Sometimes, as the phase adjustment, a signal having a phase 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 claim 7. The carrier detection means detects the carrier signal by performing band-pass filtering,
The demodulation device according to claim 2. The demodulation device according to any one of claims 2 to 11,
The phase demodulation of the wobbling signal by detecting a carrier signal from the wobbling signal read from the information recording medium by the demodulation device, to record or reproduce information on the information recording medium,
Information recording medium device.

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