JP2002074660A - Phase demodulation method, phase demodulator and information recording/reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a phase demodulation method and a phase demodulator capable of demodulating with less erroneous detection even for a low quality phase modulation signal. SOLUTION: The intrusion of noise component much influential due to its large amplitude, into a signal representing phase information is suppressed to the minimum by such a manner that phase modulation component superimposed on a wobbling signal is demodulated after the amplitude of the wobbling signal is limited by a specified level A+2α which is larger than the amplitude of the carrier component of the wobble signal obtained from media, then the demodulation with less erroneous detection is attained even for the low quality phase modulation signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DVD-ROM having a wobble including address information consisting of phase modulation in a track.
RW (Digital Video or Versatile Disk-ReWri)
Table) An information recording / reproducing apparatus for a medium such as a disk, a phase demodulating apparatus for demodulating an address in the apparatus, and a phase demodulating method thereof.

[0002]

2. Description of the Related Art Generally, in a recording medium, in order to accurately detect a linear velocity at each radial position in advance during manufacturing,
A format is adopted in which tracks are wobbled (meandering) so that the wobbling signal frequency becomes constant when CLV (constant linear velocity) rotation control is performed. Therefore, the information recording / reproducing apparatus detects the wobbling signal to control the rotation of the medium or generate a recording clock. Also, address information is required so that a recording position in an unrecorded area can be specified.
In the CD-R (Compact Disk-Recodable), the wobble of the track is frequency-modulated and address data is superimposed. Specifically, 22.
The data 1 or 0 is created with a frequency change of ± 1 kHz using 05 kHz.

On the other hand, as a method of superimposing new address information, for example, a method of performing phase modulation on a wobble has been considered as disclosed in Japanese Patent Application Laid-Open No. H10-69646. Although this phase modulation method can be classified more finely, the required information amount and the S / N (Signal Noise Ratio) of the detection signal are in a trade-off as in other modulation methods. In optical discs, the signal quality obtained from the media is poor, so that a two-phase modulation scheme (BPSK or DPSK, 0 ° and 180 °) capable of obtaining a high S / N ratio can be obtained.
Value modulation) is best. Since this modulation scheme is used for a system requiring a high S / N, one bit of data is usually represented in a plurality of carrier wave regions (time).

As a demodulation method, for example, Japanese Patent Publication No. 6-19
No. 898, a conventional technique (a method of extracting a carrier signal from a phase modulation signal and comparing the phases of the phase modulation signal and the carrier signal to demodulate the modulation data) and a general phase demodulation method The method shown in textbooks is effective. However, this two-phase modulation method has a disadvantage that the amount of information per unit time is smaller than that of a four-phase modulation method.

[0005]

SUMMARY OF THE INVENTION
As a phase demodulator for phase-modulated address information (wobbling signal), a carrier generation circuit for generating a carrier based on a wobbling signal obtained from a medium recorded by wobbling of a track having a phase modulation form; A multiplier that multiplies the wobbling signal by the carrier generated by the carrier generation circuit, and an integrator that integrates the result of the multiplication by the multiplier, and obtains a phase demodulation signal based on the result of the integration by the integrator. Has been proposed.

However, in the case of a low-quality signal in which noise is superimposed on a wobbling signal, the performance of phase demodulation deteriorates and erroneous detection frequently occurs. In particular, in the area of the optical disk after data recording, not only the noise of the power supply system but also the data component is superimposed on the wobbling signal as noise, and only a very low signal quality is often obtained. If the noise rarely has a large amplitude, the phase change of the phase-modulated wobbling signal leaks into a signal to be extracted, causing erroneous detection and deteriorating the detection accuracy of the address information.

It is therefore an object of the present invention to provide a phase demodulation method, a phase demodulator and an information recording / reproducing apparatus capable of performing demodulation with less erroneous detection even with a low-quality phase modulation signal.

[0008]

According to the first aspect of the present invention,
A phase modulation method for detecting phase information on a medium recorded by wobbling of a track having a phase modulation form, wherein the wobbling signal is obtained at a predetermined level larger than an amplitude of a carrier component of the wobbling signal obtained from the medium. After limiting the amplitude, the phase modulation component superimposed on the wobbling signal is demodulated.

Therefore, it is possible to minimize mixing of a noise component which has a large influence due to its large amplitude into a signal representing phase information, and to demodulate with little erroneous detection even with a low-quality phase modulation signal. It becomes possible. Also, since the amplitude is limited in the initial stage, there is no need to unnecessarily expand the input range of the subsequent circuit in consideration of the large amplitude component due to noise, realizing a low-potential circuit, and effectively using the dynamic range. Thus, high-resolution signal processing can be performed.

According to a second aspect of the present invention, there is provided a phase modulation method for detecting phase information on a medium recorded by wobbling of a track having a phase modulation form, wherein the phase information is superimposed on a wobbling signal obtained from the medium. A predetermined level of amplitude limitation is applied to a signal representing phase information detected in the demodulation process of the phase modulation component.

Therefore, it is possible to minimize mixing of a noise component which has a large influence due to a large amplitude into a signal representing phase information, and demodulation with less erroneous detection even with a low quality phase modulated signal can be performed. It becomes possible. In addition, it is possible to minimize the influence of the amplification of the noise component at the signal amplification point existing in the demodulation process.

According to a third aspect of the present invention, there is provided a carrier generation circuit for generating a carrier based on a wobbling signal obtained from a medium recorded by wobbling of a track having a phase modulation form, the wobbling signal and the carrier wave. A phase demodulation device comprising: a multiplier that multiplies the carrier generated by a generation circuit; and an integrator that integrates a result of the multiplication by the multiplier, wherein a phase demodulation signal is obtained based on the result of the integration by the integrator. A limiter for limiting the amplitude of the wobbling signal at a predetermined level larger than the amplitude of the carrier component of the wobbling signal obtained from the medium and input to the integrator.

Therefore, the noise component having a large amplitude and having a large influence on the signal representing the phase information can be minimized by the limiter. Demodulation becomes possible. Also,
Since the amplitude is limited at the initial stage by the limiter, it is not necessary to unnecessarily extend the input range of the subsequent circuit after the limiter in consideration of the large amplitude component due to noise, realizing a low-potential circuit and improving the dynamic range. It can be used effectively to perform high-resolution signal processing.

According to a fourth aspect of the present invention, there is provided a carrier generation circuit for generating a carrier wave based on a wobbling signal obtained from a medium recorded by wobbling of a track having a phase modulation form, the wobbling signal and the carrier wave. A phase demodulation device comprising: a multiplier that multiplies the carrier generated by a generation circuit; and an integrator that integrates a result of the multiplication by the multiplier, wherein a phase demodulation signal is obtained based on the result of the integration by the integrator. And a limiter for limiting the amplitude of the signal representing the phase information obtained from the multiplier or the integrator at a predetermined level.

Accordingly, the noise component having a large amplitude and having a large influence on the signal representing the phase information can be minimized by the limiter. Demodulation becomes possible. In addition, it is possible to minimize the influence of the amplification of the noise component at the signal amplification point existing in the demodulation process.

According to a fifth aspect of the present invention, there is provided a carrier generation circuit for generating a carrier wave based on a wobbling signal obtained from a medium recorded by wobbling of a track having a phase modulation form, the wobbling signal and the carrier wave. A phase demodulation device comprising: a multiplier that multiplies the carrier generated by a generation circuit; and an integrator that integrates a result of the multiplication by the multiplier, wherein a phase demodulation signal is obtained based on the result of the integration by the integrator. A limiter for limiting the amplitude of the integration result of the integrator during a half cycle of the carrier generated by the carrier generation circuit at a predetermined level.

Therefore, basically the same as the third or fourth aspect of the present invention, but since the carrier wave is a sine wave,
Since the positive and negative voltages are inverted between the first half cycle and the second half cycle in the cycle, the phase information can be detected through one cycle by adding each phase information detected every half cycle. In particular, by providing a limiter that limits the amplitude of the integration result of the integrator during a half cycle of the carrier generated by the carrier generation circuit at a predetermined level, the effect of noise can be suppressed most efficiently.

According to a sixth aspect of the present invention, there is provided a carrier generation circuit for generating a carrier wave based on a wobbling signal obtained from a medium recorded by wobbling of a track having a phase modulation form, the wobbling signal and the carrier wave. A phase demodulation device comprising: a multiplier that multiplies the carrier generated by a generation circuit; and an integrator that integrates a result of the multiplication by the multiplier, wherein a phase demodulation signal is obtained based on the result of the integration by the integrator. Comparing storage means for storing the integration result of the integrator for each half cycle of the carrier generated by the carrier generation circuit, and integration results for two half cycles obtained during one cycle of the carrier. A comparison unit; and a determination unit that determines the likelihood of the phase demodulation signal based on the comparison result by the comparison unit.

Therefore, paying attention to the fact that the accuracy of the demodulated information increases when the two half-cycle integration results within one cycle are the same, and that the probability of erroneous demodulation increases when the two half-cycle integration results are different. The integrated value for each cycle is stored, and the reliability of the demodulation information is determined by comparing the integrated values for two half-cycles obtained during one cycle. It is possible to obtain a criterion for determining whether a countermeasure such as a request or a supplemental request based on the surrounding information should be taken.

According to a seventh aspect of the present invention, there is provided a carrier generation circuit for generating a carrier wave based on a wobbling signal obtained from a medium recorded by wobbling of a track having a phase modulation form, Means for multiplying the wobbling signal quantized by the quantizing means and the carrier generated by the carrier generation circuit, and integrating the result of the multiplication by the multiplier. A phase demodulator that obtains a phase demodulated signal based on the result of integration by the integrator, wherein a time series of a signal or a wobbling signal representing phase information detected in a demodulation process after the quantization means is provided. Difference detecting means for detecting a difference between adjacent sampling values, and a difference detected by the difference detecting means. Comprising a differential limiter means for limiting the level of.

Therefore, the upper and lower limits of the variation (difference) of the sampling values adjacent in time series are determined by the difference limiter so that the result of integrating the other sampling values is not covered only by the data of the singular point. Thus, it is possible to prevent the result of integration of other sampling points from being overturned by a sampling value of a small number of large-amplitude signals having a singular point due to noise or the like, thereby causing a demodulation error to occur.

According to an eighth aspect of the present invention, there is provided a carrier generation circuit for generating a carrier based on a wobbling signal obtained from a medium recorded by wobbling of a track having a phase modulation form, Means for multiplying the wobbling signal quantized by the quantizing means and the carrier generated by the carrier generation circuit, and integrating the result of the multiplication by the multiplier. A phase demodulator that obtains a phase demodulated signal based on the result of integration by the integrator, wherein the signal representing phase information detected in a demodulation process after the quantization means is adjacent in time series. A singularity detecting means for detecting the singularity based on the matching sampling value, and a singularity detected by the singularity detecting means. And a correcting means for correcting, based on the sampling values before and after the adjacent time series sampling values becomes.

Therefore, it is possible not only to prevent the integration result of other sampling points from being inverted and to generate a demodulation error, but also to use a small number of singular points. It is possible to minimize the influence on the integration result of the large-amplitude signal, and to prevent a demodulation error from occurring.

An information recording / reproducing apparatus according to a ninth aspect of the present invention is an information recording / reproducing apparatus, comprising: an optical system for converging a light beam on a medium and condensing light reflected from the medium on a light receiving element; A reproduction circuit for detecting the above information;
A servo circuit for detecting position data of the condensed light beam on the medium from the light receiving element and controlling the position of the light beam on the medium based on the position data, and a mechanism for moving the position of the laser beam And a phase demodulation device according to any one of claims 3 to 8, wherein a phase demodulation signal is detected as position information of the light beam on the medium.
Is provided.

Therefore, since the phase demodulation device according to any one of claims 3 to 8 is used as the phase demodulation device,
The phase modulation information can be accurately demodulated even from a low-quality wobbling signal such as a recorded medium.

[0026]

FIG. 1 shows a first embodiment of the present invention.
A description will be given with reference to FIG. First, the schematic configuration and operation of an optical disc device, which is an information recording / reproducing device commonly used in the embodiments described below, will be described with reference to FIG.

Light emitted from a light source 1 such as a semiconductor laser is coupled to a coupling lens 2, a beam splitter 3, 1/4.
The light is focused on a recording surface 7a on a medium 7 by an optical system 6 including a wave plate 4 and an objective lens 5. The light reflected on the recording surface 7a returns to the optical system 6 again, passes through the beam splitter 3, is condensed on the light receiving element 9 by the condenser lens 8, and is converted into an electric signal. Normally, the output of the light receiving element 9 is converted from current to voltage by the I / V amplifier 10 and various calculations are performed.
The calculation may be performed with the current as it is. Usually, the light receiving element 9 and the I / V amplifier 10 are divided into a plurality of parts, and a focus error signal indicating the distance between the medium surface and the light spot focus, and a track error indicating the position of the track and the light spot on the medium surface. Calculations are performed on signals, RF signals for detecting information recorded on the recording surface 7a of the medium 7, and the like. In FIG. 1, the focus error signal and the track error signal are calculated in the servo circuit 11, and the mechanism system 12 is driven from the position data to move the light spot to the target position. Further, information on the recording surface 7a of the medium 7 is calculated into an RF signal in the reproduction circuit 13 and sent to the subsequent signal processing (not shown). Reference numeral 14 denotes a laser driver for driving the light source 1.

It is described that the phase modulation signal used in this embodiment and other embodiments described later is obtained from the reproduced signal because the detection method differs depending on the division shape of the light receiving element 9, but it is the simplest. In the following description, the push-pull signal (which is one of the track error signals) obtained from the difference between the left and right light-receiving element division lines along the track is detected. Demodulation circuit (phase demodulator) 15 based on pull signal
The description is based on the assumption that the device operates. Here, this demodulation circuit 15
Are characteristically configured for each embodiment.

First, a configuration example of the demodulation circuit 15 of the present embodiment will be described with reference to FIG. To extract the phase modulation component from the wobbling signal obtained from the optical system 6,
It is common to generate a carrier that is not modulated at the same frequency and phase as the wobbling signal and compare the phase of the carrier with the phase of the wobbling signal. Therefore, the basic phase demodulation operation of the demodulation circuit 15 will be described with reference to the block diagram shown in FIG. 2 and the phase demodulation signal waveform diagrams shown in FIGS.

First, a BPF (Band Pass Filter) is used to remove noise and phase modulation components from the wobbling signal.
A carrier signal is generated by using a carrier generation circuit 18 formed by a band limiting filter such as 16 and a PLL (Phase Locked Loop) 17 for generating a stable signal. This carrier signal has the same frequency as the wobbling signal and has a stable phase. The amplitude is desirably the same value as the fundamental wave (sine wave component excluding noise) of the wobbling signal. On the other hand, the wobbling signal is passed through, for example, an LPF (low-pass filter) (not shown) for removing only the superimposed high-frequency noise component, and then the multiplier 19
Performs the multiplication operation with the carrier signal by the carrier generation circuit 18. The phase demodulation information is obtained by inputting the output signal of the multiplier 19 to the integrator 20, the sample & hold (S / H) circuit 21 and the like. In the case of this circuit example, the output of the multiplier 19 and the output of the integrator 20 deserve a signal representing phase information.

The clear timing of the integrator 20 and S
The timing signal such as the sample / hold timing of the / H circuit 21 is generated by the timing circuit 22 based on the carrier by the carrier generation circuit 18.

In such a basic configuration, for example, a wobbling signal and a carrier signal which have been subjected to phase modulation based on phase modulation information including a constant phase region, a synchronization region and a data region, the output of the multiplier 19, and the integrator The relationship between the output of the S / H circuit 21 and the output of the S / H circuit 21 and the demodulated phase demodulation information is shown. The phase demodulation information is obtained by binarizing the output of the S / H circuit 21 at a reference level. 3 shows a state in which a high-quality wobbling signal is being demodulated, and it can be seen that the same phase demodulation information as the phase modulation information is obtained. Note that, due to the circuit configuration, data is detected with a delay of one cycle. On the other hand, FIG. 4 shows a state in which a poor-quality wobbling signal is being demodulated, and shows a situation in which an error (shaded portion) has occurred in the phase demodulation information.

Therefore, in the present embodiment, the phase modulation component superimposed on the wobbling signal is demodulated so that the same phase demodulation information as the phase modulation information can be obtained even when demodulating a low-quality wobbling signal. Before, media 7
The amplitude of the wobbling signal is limited to a predetermined level that is larger than the amplitude of the carrier component of the wobbling signal obtained from. For this reason, a limiter 23 is provided at a stage preceding the multiplier 19. This limiter 2
3, when the amplitude of the carrier frequency component of the wobbling signal is A (A: constant) peak-to-peak as shown in FIG. 5, a positive limiter voltage of + A / 2 + α as a predetermined level, and −A / 2−α , A large signal component on the + side or the − side exceeding the negative limiter voltage is removed, and the upper and lower limits are limited. α is set to an appropriate value in accordance with noise and amplitude fluctuation of the woblin signal. It is desirable that the wobbling signal has previously passed through a gain adjustment circuit that keeps the amplitude constant.

By providing the limiter 23 in this manner, for example, even in the case of demodulation from a low-quality wobbling signal in which a data component as shown in FIG. As shown in FIG. 5, since the noise component above the predetermined level of the wobbling signal is removed by the limiter 23, the adverse effect on the demodulation operation after the output of the multiplier 19 can be reduced, and the phase can be reduced according to the phase modulation information. Demodulated information can be demodulated stably.

The limiter 23 can determine an assumed input level of a subsequent circuit (ADC, multiplier 19, integrator 20, etc., which will be described later), so that a low potential circuit (amplifier, etc.) having a narrow input range can be used. become. Also, when discrete sampling is performed using an ADC or the like, the dynamic range can be set to the circuit voltage of the limiter 23, so that a configuration can be adopted in which the resolution is maximized and the signal component is efficiently demodulated.

It is to be noted that not only the amplitude of the wobbling signal is limited before the demodulation operation, but also the signal representing the phase information detected in the process of demodulating the phase modulation component superimposed on the wobbling signal obtained from the medium 7. Alternatively, a predetermined level of amplitude limitation may be applied. Therefore, FIG.
As shown therein, a limiter 24 for limiting the amplitude of the output of the multiplier 19 or the output of the integrator 20 representing the phase information may be provided. In this case, the limit level of the amplitude may be set to, for example, a level indicated by a chain line during the output of the multiplier 19 or the output of the integrator 20 in FIG. According to such a limiter 24, it is also possible to minimize the influence when the noise component is amplified at the signal amplification point existing in the demodulation process.

The waveforms shown in FIG. 3 to FIG. 5 are operation examples when the demodulation circuit 15 shown in FIG. 2 is configured in an analog manner. After the wobbling signal is quantized using an analog / digital converter (ADC) 25 as quantization means, the signal is processed.

A second embodiment of the present invention will be described with reference to FIGS. The same components as those shown in the overall configuration of the information recording / reproducing apparatus and the first embodiment are denoted by the same reference numerals, and description thereof is omitted (the same applies to the following embodiments).

First, the idea of this embodiment will be described. Generally, the unit of phase change in phase demodulation is one cycle. In order to improve the demodulation performance, a plurality of periods may be set and changed, but an integer period in units of one period is used. Since the carrier wave has a sine wave shape, positive and negative voltages are inverted in the first half period and the second half period in one period. For this reason, the demodulation circuit 15 should be able to detect the phase demodulation information over one cycle by adding each phase demodulation information detected every half cycle.

In the normal state, the first half cycle and the second half cycle should show the same result. FIGS. 6 and 7 show this state. Looking at the output of the half cycle integrator in the case of high quality shown in FIG. 6, the first half cycle and the second half cycle of one cycle show the same result, and the one cycle integration result which is the addition result is of course the same positive / negative value. Is shown. However, in the case of the low quality shown in FIG. 7, demodulation can be performed without error although the integration result has a variation except for the portion indicated by the symbol A, but only the portion indicated by the symbol A is a singular point. It can be seen that an error has occurred in the phase demodulation information due to the large noise component

This effect is likely to occur when processing digitally. This is shown in FIG. In order to perform digital processing, discrete sampling is performed by the ADC 25 or the like. However, when large noise is superimposed on the input signal at the sample timing, the sampling value is integrated with other normal amplitude sampling values. Contribution is large. When the number of times of sampling is small, the degree of contribution is higher. Depending on the magnitude of the noise sampling value, the result of integrating other sampling values may be reversed. The case shown in FIGS. 7 and 8B is the same. In particular, in the case of FIG. 7, not only the half-cycle result but also the one-cycle integration result is reversed, and an error occurs in the phase demodulation information.

In such a case, data errors increase the accuracy of demodulated information when the two half-cycle integration results within one cycle are the same, and increase the probability of error when the results are different. In this embodiment, utilizing this fact, the likelihood of the obtained phase demodulation information is determined. Therefore, the circuit is configured as shown in FIG. Here, an example of the configuration after the integrator 20 in the demodulation process is shown. The signal is output from the integrator 20 at every half cycle of the carrier signal, sampled and held by the S / H circuit 21, and the The integration result of the integrator 20 is stored in the storage means 26, and the integration result stored in the storage means 26 and the integration result obtained from the S / H circuit 21 are compared between two half cycles obtained during one cycle. The comparison result is compared by the comparing means 27 as the integration result, and the likelihood of the phase demodulation signal is determined by the determining means 28 based on the comparison result by the comparing means 27.

Therefore, paying attention to the fact that the accuracy of the demodulated information increases when the two half-cycle integration results within one cycle are the same, and that the probability of erroneous demodulation increases when the results are different. Since the integrated value of each cycle is stored and the integrated value of two half cycles obtained during one cycle is compared to determine the likelihood of the demodulated information, the case shown in FIG. 7 is used. In this case, the comparison result by the comparing means 27 is different, so that it is determined to be erroneous, and a criterion for determining whether to take a countermeasure such as a rereading request or a complementation request based on information before and after in case of important data is obtained. .

A third embodiment of the present invention will be described with reference to FIG. This embodiment is also basically the same as the second embodiment, but particularly supposes that the wobbling signal is quantized by discrete sampling using the ADC 25 to perform signal processing. is there. That is, the waveform is assumed to be as shown in FIG.

In other words, when signal processing is performed by sampling, there is a danger that, as described above with reference to FIG. 8B, the integration result of another point may be overturned when sampling a large singular noise. Therefore, in the present embodiment, in order to find such a singular point, the upper and lower limits of the variation (difference) of the sampling values adjacent in time series are determined, and the integration result of the other sampling values is determined as the singular point. Do not overturn only with the data of. For this reason, in the present embodiment, as shown in FIG. 10, storage means 29 for storing the sampling result by ADC 25, and data stored in storage means 29 and data obtained from ADC 25, that is, A difference detecting means 30 for detecting a difference between adjacent sampling values, and, when a difference signal obtained by the difference detecting means 30 is larger than a predetermined level, the difference is limited to a predetermined level. A
A difference limiter means for imposing a limit on the output from the DC;

Therefore, according to the present embodiment, the upper and lower limits of the variation (difference) of the sampling values adjacent in time series are determined by the difference limiter 31, and the integration result of the other sampling values is determined as the singular point. , So that it is possible to prevent the integration result of other sampling points from being overturned by a sampling value of a small number of singular points of a large amplitude signal caused by noise or the like, thereby causing a demodulation error. .

A fourth embodiment of the present invention will be described with reference to FIGS. In the present embodiment, the above-described third embodiment is further developed to correct the singular point sampling data in a time series based on the preceding and following sampling data. Therefore, ADC
Storage means 32a, 32b, 32c for storing three time-sequentially different sampling data on the output side of 25;
Is provided. The storage means 32a stores the oldest data,
The current data to be stored in the storage unit 2b, the storage unit 32
c will store the next data respectively. Singularity detection means 33 is provided which detects whether or not the current data is singularity data based on three time-series different sampling data stored in these storage means 32a, 32b, 32c. Correction means 34 is provided for correcting the current data output from the storage means 32b based on the result.

For example, as shown in FIG. 12, while calculating a and b corresponding to the variation (difference) of the sampling value, a
When b and b exceed a predetermined value, the singular point detecting means 33 recognizes that the sampling value is a singular point, and the correcting means 34 performs correction to replace the average value of the preceding and succeeding sampling data. As a result, the integrated value output becomes the original plus side as shown by the thick line in FIG. 12, and the data error due to the singular point is corrected.

Therefore, according to the present embodiment, it is possible to prevent a sampling value of a small number of singular points of a large-amplitude signal due to noise or the like from inverting the integration result of another sampling point and causing a demodulation error. In addition to the above, it is possible to minimize the influence of the small number of singular points on the integration result of the large amplitude signal, thereby preventing the occurrence of a demodulation error.

[0050]

According to the phase demodulation method of the first aspect of the present invention, the amplitude of the wobbling signal is limited to a predetermined level larger than the amplitude of the carrier component of the wobbling signal obtained from the medium, and then superimposed on the wobbling signal. Since the phase modulation component is demodulated, it is possible to minimize the noise component that has a large influence due to the large amplitude and to be mixed into the signal representing the phase information. Demodulation with few false detections is possible,
In addition, since the amplitude is limited in the initial stage, there is no need to unnecessarily expand the input range of the subsequent circuit in consideration of the large amplitude component due to noise.
High resolution signal processing can be performed by effectively using the dynamic range.

According to the phase demodulation method of the present invention, the signal representing the phase information detected in the process of demodulating the phase modulation component superimposed on the wobbling signal obtained from the medium has a predetermined level. Amplitude limitation is applied, so that noise components that have a large influence due to their large amplitude can be minimized from being mixed into the signal that represents the phase information. Demodulation can be performed, and the effect of the amplification of the noise component at the signal amplification point existing in the demodulation process can be minimized.

According to the phase demodulator of the invention, a limiter for limiting the amplitude of the wobbling signal at a predetermined level larger than the amplitude of the carrier component of the wobbling signal obtained from the medium and input to the integrator is provided. The limiter minimizes the noise component that has a large amplitude and has a large effect on the signal representing the phase information, so that demodulation with less erroneous detection can be performed even with a low-quality phase modulation signal. In addition, since the amplitude is limited at the initial stage by the limiter, it is not necessary to unnecessarily expand the input range of the subsequent circuit after the limiter in consideration of the large amplitude component due to noise, realizing a low potential circuit. Also, high resolution signal processing can be performed by effectively using the dynamic range.

According to the fourth aspect of the present invention, since the limiter for limiting the amplitude of the signal representing the phase information obtained from the multiplier or the integrator at a predetermined level is provided, the influence is large because of the large amplitude. The limiter can minimize the noise component from being mixed into the signal representing the phase information, and can demodulate the signal even if it is a low-quality phase-modulated signal with less erroneous detection. The effect when the noise component is amplified at the point can also be minimized.

According to the fifth aspect of the present invention, basically the same as the third or fourth aspect of the present invention, but since the carrier wave has a sine wave shape, the first half period and the second half period within one cycle are different. Pay attention to the fact that the phase information can be detected throughout one cycle by adding each phase information detected every half cycle because of the feature that the positive and negative voltages are inverted. In particular, the phase information is generated by the carrier generation circuit. By providing a limiter for limiting the amplitude of the integration result of the integrator during a half cycle of the carrier wave at a predetermined level, the effect of noise can be suppressed most efficiently.

According to the phase demodulation apparatus of the present invention, the accuracy of the demodulated information increases when the two half-cycle integration results within one cycle are the same, and when the two half-cycle integration results are different, the probability of erroneous demodulation is incorrect. Paying attention to the point that the signal becomes higher, storing the integrated value for each half cycle of the carrier wave, and comparing the integrated values for two half cycles obtained during one cycle to determine the likelihood of the demodulation information. Therefore, it is possible to obtain a criterion for determining whether to take a countermeasure such as a rereading request for important data or a complementing request based on the surrounding information.

According to the phase demodulation apparatus of the present invention, the variation (difference) between the sampling values adjacent in time series.
The upper and lower limits of are determined by the difference limiter, and the integration result of the other sampling values is not covered only by the data of the singular point, so that the sampling value of a small number of singular point large amplitude signals caused by noise etc. Thereby, it is possible to prevent the result of integration of other sampling points from being reversed and generating a demodulation error.

According to the phase demodulation apparatus of the present invention, the sampling result of a small number of singular points of a large amplitude signal caused by noise or the like reverses the integration result of other sampling points and generates a demodulation error. In addition to preventing the occurrence of demodulation errors, it is possible to minimize the influence of the small number of singular points on the integration result of the large-amplitude signal.

According to the information recording / reproducing apparatus according to the ninth aspect of the present invention, since the phase demodulating apparatus according to any one of the third to eighth aspects is used as the phase demodulating apparatus, a low quality medium such as a recorded medium can be used. The phase modulation information can be accurately demodulated even from the wobbling signal.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an optical disk device common to each embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration example of a demodulation circuit according to the first embodiment of the present invention.

FIG. 3 is an explanatory diagram of signal waveforms showing phase demodulation in a case of high quality.

FIG. 4 is an explanatory diagram of signal waveforms showing conventional phase demodulation in a case of low quality.

FIG. 5 is an explanatory diagram of signal waveforms showing phase demodulation of the present embodiment in the case of low quality.

FIG. 6 is an explanatory diagram of a signal waveform showing a case of a high quality signal for explaining a second embodiment of the present invention.

FIG. 7 is an explanatory diagram of a signal waveform showing a case of a low-quality signal in order to explain a second embodiment of the present invention.

FIG. 8 is an explanatory signal waveform diagram showing a case of a high quality signal and a case of a low quality signal in order to explain a case by digital processing.

FIG. 9 is a block diagram illustrating a configuration example in which a part of a demodulation circuit according to a second embodiment of the present invention is extracted.

FIG. 10 is a block diagram illustrating a configuration example in which a part of a demodulation circuit according to a third embodiment of the present invention is extracted.

FIG. 11 is a block diagram illustrating a configuration example in which a part of a demodulation circuit according to a fourth embodiment of the present invention is extracted.

FIG. 12 is an explanatory diagram of the signal waveform.

[Description of Signs] 6 Optical system 7 Media 9 Light receiving element 11 Servo circuit 12 Mechanical system 13 Reproduction circuit 15 Phase demodulator 18 Carrier generation circuit 19 Multiplier 20 Integrator 23 Limiter 24 Limiter 25 Quantization means 26 Storage means 27 Comparison means 28 determination means 30 difference detection means 31 difference limiter means 33 singular point detection means 34 correction means

Claims (9)

[Claims] 1. A phase modulation method for detecting phase information on a medium recorded by wobbling of a track having a phase modulation form, wherein the predetermined level is larger than an amplitude of a carrier component of a wobbling signal obtained from the medium. A phase demodulation method characterized in that, after limiting the amplitude of the wobbling signal, the phase modulation component superimposed on the wobbling signal is demodulated. 2. A phase modulation method for detecting phase information on a medium recorded by wobbling of a track having a phase modulation form, wherein a phase modulation component superimposed on a wobbling signal obtained from the medium is provided. A phase demodulation method, wherein a signal representing phase information detected in a demodulation process is subjected to a predetermined level of amplitude limitation. 3. A carrier wave generating circuit for generating a carrier wave based on a wobbling signal obtained from a medium recorded by wobbling of a track having a phase modulation form, and a carrier wave generated by the wobbling signal and the carrier wave generating circuit. A multiplier for multiplying the carrier wave, and an integrator for integrating the multiplication result by the multiplier, a phase demodulation device that obtains a phase demodulation signal based on the integration result by the integrator, obtained from the medium And a limiter for limiting the amplitude of the wobbling signal at a predetermined level larger than the amplitude of the carrier component of the wobbling signal input to the integrator. 4. A carrier wave generating circuit for generating a carrier wave based on a wobbling signal obtained from a medium recorded by wobbling of a track having a phase modulation form, and a wobbling signal and a carrier wave generated by the carrier wave generating circuit. A phase demodulation device that includes a multiplier that multiplies the carrier and an integrator that integrates a multiplication result by the multiplier, and obtains a phase demodulation signal based on the integration result by the integrator. A phase demodulator comprising a limiter for limiting an amplitude of a signal representing phase information obtained from an integrator at a predetermined level. 5. A carrier generation circuit for generating a carrier based on a wobbling signal obtained from a medium recorded by wobbling of a track having a phase modulation form, and a wobbling signal generated by the wobbling signal and the carrier generation circuit. A phase demodulator that includes a multiplier that multiplies the carrier and an accumulator that accumulates the result of the multiplication by the multiplier, wherein the phase demodulator obtains a phase demodulated signal based on the result of the integration by the accumulator. A phase demodulator, comprising: a limiter that limits an amplitude at a predetermined level with respect to an integration result of the integrator during a half cycle of a generated carrier wave. 6. A carrier generation circuit for generating a carrier based on a wobbling signal obtained from a medium recorded by wobbling of a track having a phase modulation form, and a carrier generated by the wobbling signal and the carrier generation circuit. A phase demodulator that includes a multiplier that multiplies the carrier and an accumulator that accumulates the result of the multiplication by the multiplier, wherein the phase demodulator obtains a phase demodulated signal based on the result of the integration by the accumulator. Storage means for storing the integration result of the integrator for each half cycle of the generated carrier wave, and comparison means for comparing the integration results for two half cycles obtained during one cycle of the carrier wave; Determining means for determining the likelihood of the phase demodulated signal based on the result of the comparison by the means. 7. A carrier wave generating circuit for generating a carrier wave based on a wobbling signal obtained from a medium recorded by wobbling of a track having a phase modulation form, and quantizing the wobbling signal by discrete sampling. A quantizing means, a multiplier for multiplying the wobbling signal quantized by the quantizing means and the carrier generated by the carrier generating circuit, and an integrator for multiplying a result of the multiplication by the multiplier. A phase demodulation device for obtaining a phase demodulated signal based on a result of integration by the integrator, wherein a signal representing phase information detected in a demodulation process after the quantization means or a sampling value adjacent in time series of a wobbling signal Difference detecting means for detecting a difference between the two, and a difference for limiting the difference detected by the difference detecting means to a predetermined level. Phase demodulator, characterized in that it comprises a limiter means. 8. A carrier generation circuit for generating a carrier based on a wobbling signal obtained from a medium recorded by wobbling of a track having a phase modulation form, and quantizing the wobbling signal by discrete sampling. A quantizing means, a multiplier for multiplying the wobbling signal quantized by the quantizing means and the carrier generated by the carrier generating circuit, and an integrator for multiplying a result of the multiplication by the multiplier. A phase demodulation device for obtaining a phase demodulated signal based on the result of integration by the integrator, wherein the phase demodulation signal is obtained based on a time-series adjacent sampling value of a signal representing phase information detected in a demodulation process after the quantization means. A singularity detecting means for detecting a singularity; and a sampling for the singularity detected by the singularity detecting means. Phase demodulator, wherein a correcting means for correcting, based on the sampling values before and after adjacent in time series, a by comprising a. 9. An optical system for converging a light beam on a medium and condensing light reflected from the medium on a light receiving element, a reproducing circuit for detecting information on the medium from the light receiving element, A servo circuit that detects position data of the illuminated light beam on the medium from the light receiving element and controls the position of the light beam on the medium based on the position data; and a mechanism system that moves the position of the laser light. An information recording / reproducing apparatus, comprising: the phase demodulation apparatus according to claim 3, wherein a phase demodulation signal is detected as position information of the light beam on the medium.