JP2001052446A - Demodulation circuit and information recording and reproducing device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a demodulation circuit capable of accurately demodulating data signals whose phase is inverted in a short carrier wave section. SOLUTION: In this demodulation circuit, by providing a polarity change circuit 22 for inverting the polarity of phase modulation signals corresponding to inversion signals by an inversion signal generation circuit 23, the polarity of the phase modulation signals is inverted corresponding to the inversion timing of the phase inside unit information constituted by including the inversion of the phase and phase demodulation information is obtained. Thus, performance required for the demodulation circuit, the acceleration of a circuit required for detecting the inversion of the phase and measures against the increase of noise and the reduction of an output amplitude, etc., due to synchronous detection accompanying the change point of the phase for instance, is mitigated and the highly reliable demodulation circuit 15 of simple constitution is attained.

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 and a demodulation circuit for demodulating an address in the apparatus.

[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 so that the wobble signal frequency becomes constant when CLV rotation control is performed. Therefore, the information recording / reproducing apparatus detects the wobble signal to control the rotation of the medium or generate a recording clock. Also, address information is necessary so that a recording position in an unrecorded area can be specified. However, CD-R (Compact Disk-Recod)
In (able), address data is superimposed by performing frequency modulation on the wobble of the track described above. In particular,
22.05 kHz is used as a carrier wave, and data 1 or 0 is generated with a frequency change of ± 1 kHz.

[0003]

As a method of superimposing new address information, for example, a method of performing phase modulation on wobbles 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, since the signal quality obtained from the medium is poor, a two-phase modulation method (BPSK or DPSK, 0 ゜ and 1) that can obtain a high S / N ratio can be obtained.
80 ° binary modulation) is best. This modulation scheme has a high S
Since / N is used for a system requiring data, one bit of data is usually represented in a plurality of carrier 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] The address information of the optical disk is composed of a synchronization signal indicating a data reference position and a data signal. Normally, it is preferable that the synchronization signal can be detected without performing a special operation. Therefore, in the case of phase modulation, a specific carrier section is a signal having a phase opposite to that of the carrier. In order not to reduce the amount of information, a carrier wave section as short as possible is desired.

However, the data signal must be a signal that can be completely distinguished from the synchronization signal. In addition, since the number of the data signal is larger than that of the synchronization signal, the anti-phase state of the carrier wave section longer than the synchronization signal must be reduced in order not to reduce the amount of information. It is desired that the assignment is not performed and the phase is inverted within a short section.

However, when the phase is inverted in a short section,
The detection signal is small and noisy, and erroneous detection is likely to occur.

Accordingly, an object of the present invention is to provide a demodulation circuit capable of accurately demodulating a data signal whose phase is inverted within a short carrier wave section, and an information recording / reproducing apparatus using the same.

Further, as described above, the two-phase modulation method itself has a problem that the amount of information is small. In order to increase the amount of information as much as possible, the phase may change for each carrier. Since the circuit has a problem that sufficient performance cannot be obtained as a demodulation performance, an object of the present invention is to provide a demodulation circuit capable of demodulation with high accuracy and an information recording / reproducing apparatus using the same.

[0010]

According to the first aspect of the present invention,
A demodulation circuit for detecting position data on a medium recorded by wobbling of a track using a two-phase modulation method for forming unit information including phase inversion, wherein a phase modulation signal obtained from the medium is provided. A carrier recovery circuit that detects a carrier from the synchronous detection circuit that compares the phase modulation signal and the phase of the carrier, an inversion signal generation circuit that outputs an inversion signal according to the inversion timing of the phase of the unit information, A polarity changing circuit for inverting the polarity of the phase modulation signal in accordance with an inversion signal, wherein phase demodulation information is detected from an output signal level of the synchronous detection circuit to obtain position data on the medium.

Therefore, the phase demodulation information is obtained by inverting the polarity of the phase modulation signal in accordance with the phase inversion timing in the unit information including the phase inversion.
The following performance required for the demodulation circuit, that is, an increase in the speed of the circuit required to detect phase inversion, an increase in noise due to performing synchronous detection with a phase change point, and an increase in output amplitude Countermeasures such as reduction can be eased, and a highly reliable demodulation circuit with a simple configuration can be obtained.

According to a second aspect of the present invention, in addition to the demodulation circuit of the first aspect, a first conversion having data conversion and inverse conversion characteristics of phase demodulation information generated by inverting the polarity of the phase modulation signal. A circuit for obtaining position data on the medium from an output of the first conversion circuit.

Therefore, since the simple data conversion caused by inverting the polarity of the phase modulation signal is returned to the original information, it is possible to change the modulation rule of the position data on the medium which has already been determined without changing it. A highly reliable demodulation circuit with a simple configuration can be obtained.

According to a third aspect of the present invention, in the demodulation circuit according to the first or second aspect, the position data includes a synchronization signal and a data signal of an information sequence different from the synchronization signal, and the inverted signal generation circuit includes The inverted signal is generated based on a synchronization signal.

Therefore, since the inverted signal is generated based on the synchronization signal, the use or non-use of the demodulation circuit can be assigned to each area on the medium, and the inverted signal can be assigned to an area where high reliability is required. In addition to the use or non-use of special information that does not include phase inversion in the unit information, this circuit is a normal demodulation circuit without inversion, so selection of use or non-use is simple. .

According to a fourth aspect of the present invention, there is provided a demodulation circuit for detecting position data on a medium recorded by wobbling of a track by using a phase modulation method, wherein a carrier wave is obtained from a phase modulated signal obtained from the medium. , A synchronous detection circuit for comparing the phase modulation signal and the phase of the carrier, a plurality of integration circuits for integrating output signals of the synchronization detection circuit at different timings, and an output of the integration circuit. A sample circuit for sequentially sampling,
The phase demodulation information is detected from the output signal level of the sample circuit, and the position data on the medium is obtained.

Therefore, the phase demodulation information is obtained by continuously accumulating the phase comparison result by a plurality of integration and sample circuits for integrating and sampling the phase comparison result between the phase modulation signal and the carrier at different timings, thereby obtaining the minimum phase. Even when the inversion interval is one carrier, phase modulation information can be detected with good C / N, and the discharge time of the integration circuit can be sufficiently obtained.

According to a fifth aspect of the present invention, in the demodulation circuit according to the fourth aspect, the integration timing of the integration circuit and the sampling timing of the sample circuit are variable at an integral multiple of the period of the carrier wave.

Therefore, since the integration timing and the sample timing of the integration circuit are variable at an integral multiple of the carrier wave period, the length of the phase information (the number of carriers forming the unit information) differs between the synchronization signal and the data signal. A demodulation circuit with high reliability can be obtained by performing demodulation at an optimal integration and sample timing that differs for each information type and format.

According to a sixth aspect of the present invention, in the demodulation circuit according to the fourth or fifth aspect, the position data comprises a synchronization signal and a data signal of an information sequence different from the synchronization signal, and the position data is based on the synchronization signal. An integration timing and the sample timing are generated.

Accordingly, since the integration and sample timing are generated based on the synchronization signal, the use or non-use of the demodulation circuit can be assigned to each area on the medium, and the area where high reliability is required. In addition to being able to select the use for special information that does not include phase inversion in the unit information, this circuit can be used as a normal demodulation circuit if integration and sampling are performed sequentially for each carrier cycle. Selection of non-use becomes simple.

According to a seventh aspect of the present invention, in addition to the demodulation circuit according to the fourth, fifth or sixth aspect, data conversion of phase demodulation information caused by intermittently changing the integration timing and the sample timing is provided. A second conversion circuit having an inverse conversion characteristic is provided, and position data on the medium is obtained from an output of the second conversion circuit.

Therefore, since the simple data conversion caused by the intermittent change of the integration and the sample timing is returned to the original information, the modulation rule of the position data on the medium which has already been determined is changed. Therefore, a highly reliable demodulation circuit with a simple configuration can be obtained.

An eighth aspect of the present invention is a demodulation circuit for detecting position data on a medium recorded by wobbling of a track by using a two-phase modulation method for forming unit information including phase inversion. A carrier recovery circuit for detecting a carrier from a phase modulated signal obtained from the medium; a synchronous detection circuit for comparing the phase of the carrier with the phase modulated signal; and a reversal according to a phase reversal timing of the unit information. An inversion signal generation circuit that outputs a signal, a polarity change circuit that inverts the polarity of the phase modulation signal in accordance with the inversion signal, a plurality of integration circuits that integrate output signals of the synchronous detection circuit at different timings, A sampling circuit for sequentially sampling the output of the integration circuit; detecting phase demodulation information from an output signal level of the sampling circuit; And to obtain the position data.

Therefore, since the first and fourth aspects are combined, not only the effects of the first and fourth aspects can be obtained, but also
A phase change in the unit information section is eliminated by inverting the phase modulation signal, and a higher C / N can be obtained by increasing an integral value by accumulating all the phase comparison results. By successively using them, it is possible to obtain a sufficient time for discharging the increased charging voltage of the integrating circuit.

According to a ninth aspect of the present invention, in addition to the demodulation circuit of the eighth aspect, the polarity of the phase modulation signal is inverted, and the integration timing and the sample timing are intermittently changed. A third conversion circuit having data conversion and inverse conversion characteristics of phase demodulation information generated in
The position data on the medium is obtained from the output of the third conversion circuit.

Accordingly, simple data conversion caused by inverting the polarity of the phase modulation signal and intermittently changing the integration and sample timing is returned to the original information. , 7 can be realized by one circuit.

An information recording / reproducing apparatus according to a tenth aspect of the present invention is an information recording / reproducing apparatus, wherein 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 the position data of the focused 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 moving the position of the laser beam And a mechanism system.
The position data on the medium is detected by using the demodulation circuit according to any one of (1) to (9).

Therefore, since the demodulation circuit according to any one of claims 1 to 9 is used as a demodulation circuit of an information recording / reproducing apparatus, an inexpensive and highly reliable apparatus can be manufactured.

[0030]

FIG. 1 shows a first embodiment of the present invention.
A description will be given with reference to FIG.

First, the schematic structure and operation of an optical disk device, which is an information recording / reproducing device commonly used in embodiments described later, 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 divisional 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. Description will be made on the assumption that the demodulation circuit 15 operates based on the pull signal. Here, the demodulation circuit 15 is characteristically configured for each embodiment.

First, a first embodiment corresponding to the first, second, third and tenth aspects of the present invention will be described. FIG.
FIG. 3 is a block diagram of an embodiment of a demodulation circuit 15 corresponding to the first and second aspects of the present invention, and FIG. 3 is an explanatory diagram of signal waveforms.

Based on the phase modulation signal detected from the medium 7, a carrier signal having a reference phase is generated by a carrier reproducing circuit 21. On the other hand, the polarity of the phase modulation signal is changed in the polarity changing circuit 22 according to the output signal from the inverted signal generating circuit 23. The synchronous detection circuit 24 detects the phase difference between the carrier signal and the output of the polarity changing circuit 22. In the case of two-phase modulation, which is the object of the present embodiment, since the phase change is only two phases of 0 ° and 180 °, the synchronous detection circuit 24
Can take only two states of 0 or 1. At this time, when the input of the inversion signal does not enter the polarity changing circuit 22, the state as shown in FIG. 3A is obtained, and the phase modulation information recorded on the medium 7 is directly used as the synchronous detection circuit 2.
4 is detected. A signal obtained by binarizing this signal (a low-pass filter or the like may be inserted) becomes phase demodulation information (the first conversion circuit will be described later). Further, in order to obtain basic position data before phase modulation, The data demodulation circuit 25 demodulates data. The polarity changing circuit 22 is the greatest feature of the present embodiment, and a system without the polarity changing circuit 22 is referred to as a “conventional demodulation method” for convenience.

In the present embodiment, the phase modulation method is used to “form unit information including phase inversion”. However, as shown in FIG. 9A, the position data unit (BIT) is formed from two carrier waves. BIT0 is 0 & 1, B
IT1 represents a modulation format including 1 & 0 and inversion of wobble. Although the position data is 0,
The information recorded in the wobble is 2 when the phase modulation is performed.
It is converted into a 1 & 0 wobble combination using a carrier section. In the case of the “conventional demodulation method” in which the phase modulation signal is not inverted, the signal level of the output of the synchronous detection circuit 24 fluctuates in units of one carrier in the data signal area, and a high-speed circuit is required. Considering the detection error, a high S / N of the signal is required.

FIG. 3B shows the case of the present embodiment having the polarity changing circuit 22. The inversion signal is shown to be generated at the timing when the phase is inverted in the unit information of the data signal area. The phase modulation signal inverted at the timing of the inversion signal, that is, the output of the polarity changing circuit 22 is compared with the phase of the carrier wave, and the output of the synchronous detection circuit 24 is obtained. Looking at the characteristics of this signal, the signal level changes in units of at least two carriers. 1 is 0 for 1 BIT of position data
In & 0, 0 is a continuous signal level of 1 & 1, so
The speed of the detection circuit may be lower than that of the "conventional demodulation method" and the S / N of the signal may be lower.

However, if the inverted signal is used, the phase modulation information engraved on the wobble and the detected synchronous detection circuit 2
A simple conversion rule occurs between the output of C.4 and C.4. Therefore,
In an embodiment corresponding to claim 2, a first conversion circuit 26 having a conversion rule reverse to the conversion rule generated by inverting the phase modulation signal is mounted, and the data is inverted by the polarity changing circuit 22 and converted. The information that has been performed is restored. Note that, like the polarity changing circuit 22, the first conversion circuit 26 operates only when inversion is performed. Of course, the first conversion circuit 26 does not need to be independent, and the data demodulation circuit 25 itself may have a configuration having the characteristics of the first conversion circuit 26 as well. Although the present embodiment has been described using the data area, the present invention can be used for a special signal sequence such as a synchronization signal area.

Here, an embodiment corresponding to claim 3 will be described with reference to FIG. Location data is usually
It consists of a synchronization signal (Sync) and a data signal (Data). It is necessary to accurately determine at least two types of patterns in the data, but it is only necessary to be able to determine the presence / absence of a synchronization signal, and a special pattern is formed so that detection can be performed relatively easily without performing special processing for detection. I have. In each format, the position of the data signal from the synchronization signal is specified. Therefore, if the synchronization signal is detected without performing the inversion, and the inversion signal is generated after a predetermined time based on the synchronization detection signal, it is possible to generate the inversion signal that matches the inversion timing of the phase in the data signal. .

As described above, according to the present embodiment, the phase demodulation information is obtained by inverting the polarity of the phase modulation signal in accordance with the phase inversion timing in the unit information including the phase inversion. Therefore, the following performance required for the demodulation circuit 15, that is, an increase in the speed of the circuit required to detect phase inversion and an increase in noise due to performing synchronous detection with a phase change point Thus, measures such as a decrease in output amplitude can be relaxed, and a highly reliable demodulation circuit can be obtained with a simple configuration. Also, since simple data conversion caused by inverting the polarity of the phase modulation signal is returned to the original information,
The demodulation circuit 15 has a simple configuration and high reliability without changing the modulation rule of the position data on the medium 7 which has already been determined. Furthermore, since the inverted signal is generated based on the synchronization signal, the use or non-use of the demodulation circuit 15 can be assigned to each area on the medium 7, and the use of the demodulation circuit 15 in an area where high reliability is required can be assigned. And unit information can be selected not to be used for special information that does not include phase inversion, and since this demodulation circuit 15 is a normal demodulation circuit without inversion, selection of use or non-use is simple. is there.
Further, even when viewed as an information recording / reproducing apparatus, since the demodulation circuit 15 as described above is used, an inexpensive and highly reliable apparatus can be manufactured.

A second embodiment of the present invention will be described with reference to FIGS. The same parts as those described in the above-described embodiment are denoted by the same reference numerals, and description thereof will be omitted. This embodiment corresponds to the invention described in claims 4, 5, 6, 7 and 10.

In the present embodiment, the output of the synchronous detection circuit 24 is used as an input signal, and it is assumed that the “conventional demodulation method” is used for the stage preceding the synchronous detection circuit 24. The output of the synchronous detection circuit 24 is input to a plurality of (in this embodiment, two examples denoted by A and B, respectively) integration circuits A31 and B32. The output is sampled at a specific timing in the sampling circuits A33 and B34 and then held, and the plurality of integrating circuits A31 and B34 are held.
Phase demodulation information is obtained by sequentially selecting the outputs of B32 and the sample circuits A33 and B34. Based on the phase demodulation information, the data demodulation circuit 25 generates position data in the same manner as in the first embodiment. Basically, if the integration and sampling operations are performed for each carrier, the second conversion circuit 35 shown in FIG. 5 is not necessary.

FIG. 6 shows an example of a signal waveform in the case of the configuration example corresponding to claim 4. In this case, two integrators A31 and B32 and a sampler A3 in one carrier cycle.
3 and B34 operate in place of each other. The output signal of the synchronous detection circuit 24 is integrated at different timings in the integration circuits A31 and B32. 1 each
At the timing when the integration of the carrier wave is completed, the integrated values are sampled by the sample circuits A33 and B34 at the subsequent stage,
By switching and selecting the hold output of the sample circuit A33 and the sample circuit B34 in one carrier cycle, a phase demodulation signal having a large amplitude can be continuously obtained by reflecting the results of all the phase comparisons. In order to perform the integration operation, phase demodulation information is obtained with a delay of one carrier. The integration and sample timing are repeated every carrier cycle as shown.

It is desirable that each of the integrating circuits A31 and B32 be reset (discharged) before the next operation timing. Although the circuit configuration of the present embodiment is a pair of an integration circuit and a sample circuit, a configuration in which the outputs of a plurality of integration circuits are sampled by one sample circuit is also possible. A circuit having only one set of an integrating circuit and a sample circuit is already known. However, in the case of only one set, it is necessary to stop the integration operation during sampling by the sample circuit or to output while performing sampling simultaneously during the integration operation. Therefore, all of the phase comparison results cannot be reflected, or the output becomes unstable. Further, other conventional methods not using an integrating circuit (for example, Japanese Patent Publication No. 6-198)
In the example described in Japanese Patent Publication No. 98), the output signal of the synchronous detection circuit 24 in FIG. 5 is simply passed through a low-pass filter, so that the S / N of the signal is clearly poor and not suitable for high-speed demodulation. In this regard, in the present embodiment, the integration circuits A31, B3
2, the phase comparison results are accumulated and detected, and the plurality of integration circuits A31 and B32 are switched to continuously reflect the phase comparison results.
/ N can be obtained. In addition, by using the method of the present embodiment, demodulation can be performed without any problem even in a phase modulation format in which a phase change occurs in units of one carrier.

As described above, a plurality of integrating circuits A31 and B32 and a sample circuit A33, which integrate and sample the phase comparison result between the phase modulation signal and the carrier at different timings.
Since the phase demodulation information is obtained by continuously accumulating the phase comparison result with B34, the phase modulation information can be detected with good C / N even when the minimum phase inversion interval is one carrier,
The discharge time of the integration circuits A31 and B32 can be sufficiently obtained.

Next, FIG. 7 shows a signal waveform diagram in the case of the configuration example corresponding to claim 5. Normally, the integration and sample timing are set to a specific integer multiple of the carrier. In the example shown, 1
It is twice. In this case, as described above, the phase modulation information can be directly demodulated with a delay of one carrier. Although the S / N of the detection signal is improved due to the integration method, if the quality of the phase modulation signal such as the wobble signal in the recorded area on which the reproduction signal is superimposed is significantly deteriorated, the S / N is further improved.
An improvement in N is desired. In a configuration example corresponding to claim 5,
For this purpose, the S / N is increased by integrating the result of the phase comparison for an integral multiple of the carrier wave. In the example shown in FIG. 7, three-carrier time integration is performed continuously. During integration, a signal obtained by sampling the output of the other integration circuit A31 or B32 is maintained as an output. This method requires that the data area be at a specific position and that the polarity of the phase comparison result be constant during the integration time so that special integration timing and sample timing signals can be generated. S / N is obtained.

However, when the integration and sample timing are changed in this way, a specific conversion rule occurs between the phase modulation information on the medium 7 and the phase demodulation information output from the demodulation circuit 15 of the present embodiment. As shown in FIG. 7, when three carrier integration is performed, '010001' is converted to '011101'. Therefore, in a configuration example corresponding to claim 7, as shown in FIG. 5, a second conversion circuit 35 having a conversion rule opposite to a conversion rule generated by changing the integration and sample timing is mounted. Conversion is performed so that phase demodulation information equal to the phase modulation information can be obtained. Note that the second conversion circuit 35 may have the same conversion performance as the data demodulation circuit 25 in the same manner as in the configuration example according to claim 2.

The configuration example corresponding to claim 7 is the same as the case corresponding to claim 3, except that a synchronization signal is detected, and the integration timing and the integration timing are determined every time set based on the synchronization detection signal. In addition to generating a sample timing, it is possible to specify only a place where a phase inversion does not occur in a data area where a high S / N is required, and generate a signal of a different length only in that area.

Even in the present embodiment, when viewed as an information recording / reproducing apparatus, an inexpensive and highly reliable apparatus can be manufactured since the demodulation circuit 15 as described above is used.

A third embodiment of the present invention will be described with reference to FIG. This embodiment corresponds to the eighth, ninth, and tenth aspects of the present invention. In the present embodiment, the circuit shown in FIG. 2 for generating the input signal of the demodulation circuit 15 shown in FIG. 5, that is, a circuit configuration including an alligator polarity changing circuit 22 at the input of the synchronous detection circuit 24 is used. An example of the effect obtained by combining the first and second embodiments will be described with reference to FIG. This is an example in which BIT, which is the minimum unit of data included in the position data, is composed of four carriers. When BIT = 0, phase modulation is “0011”, and when BIT = 1, it is “1100”. In the figure, BIT = 0 is shown. Since the data portion is formed by phase modulation of four carriers inverted by two carriers, an inverted signal representing the timing of phase conversion in data is generated from the synchronization signal. The synchronous detection circuit 24 detects the phase difference between the phase modulation signal inverted by the polarity change circuit 22 and the carrier generated from the phase modulation signal by the inverted signal. In this example, the input phase modulation information is “0100110”, but the output of the synchronous detection circuit 24 is “0100000” because the inversion was performed. This signal is divided into two systems of integrating circuits A31 and B32 and a sample circuit A.
At 33 and B34, sampling is normally performed alternately for each carrier, but the four carrier sections of the data section are divided into one of the integrating circuits A3.
Integrate continuously at 1 or B32. As a result, an integrated voltage corresponding to four carrier waves is obtained, a very large signal is obtained, and a high S / N can be obtained. This signal is “0111100”, which is “xxx0” when compared with “0011” indicating BIT = 0 of the phase modulation information on the medium 7. 'x' changes according to the immediately preceding data, and the last 0 is the integration result. For this reason, in the configuration example corresponding to claim 9, a third method for restoring the conversion of the data generated due to the inversion and integration of the phase modulation signal and the change of the sample timing is used.
, That is, a circuit having a function corresponding to claims 2 and 7. Note that the third conversion circuit 26 and the second conversion circuit 35 are mounted,
Since the conversion circuit can arrange and simplify the conversion rules, the scale becomes smaller. Needless to say, the data demodulation circuit 25 may have the above-described functions as in the case of the configuration examples corresponding to the second and seventh aspects.

As described above, according to the present embodiment, since the first and second embodiments are combined, not only the effects of both embodiments can be obtained, but also the unit information section can be obtained by inverting the phase modulation signal. And the higher integrated value due to the elimination of the phase change of
/ N, and a plurality of integrating circuits A3
By using the B1 and B32 sequentially, it is possible to obtain a sufficient time for discharging the increased charging voltage. Also, since the simple data conversion caused by inverting the polarity of the phase modulation signal and intermittently changing the integration and sample timing is returned to the original information by the third conversion circuit, The demodulation circuits required for each can be realized by one circuit. Also, when viewed as an information recording / reproducing device,
Since the demodulation circuit as described above is used, an inexpensive and highly reliable device can be manufactured.

[0052]

According to the present invention, the phase demodulation information is obtained by inverting the polarity of the phase modulation signal in accordance with the phase inversion timing in the unit information including the phase inversion. Therefore, the following performance required for the demodulation circuit, that is, an increase in the speed of the circuit required to detect phase inversion and an increase in noise due to performing synchronous detection with a phase change point Therefore, measures such as a decrease in output amplitude can be eased, and a highly reliable demodulation circuit can be obtained with a simple configuration.

According to the second aspect of the present invention, simple data conversion caused by inverting the polarity of the phase modulation signal can be performed by:
Because we restored the original information, without changing the already determined modulation rule of the position data on the media,
A highly reliable demodulation circuit can be obtained with a simple configuration.

According to the third aspect of the present invention, since the inverted signal is generated based on the synchronization signal, use or non-use of the demodulation circuit can be assigned to each area on the medium, and high reliability can be obtained. In addition to being able to select the use for areas where responsivity is required and the use for special information that does not include phase inversion in the unit information, this circuit becomes a normal demodulation circuit without inversion Therefore, selection of use or nonuse can be simplified.

According to the fourth aspect of the present invention, the plurality of integrating and sampling circuits for integrating and sampling the phase comparison result between the phase modulation signal and the carrier at different timings continuously accumulate the phase comparison result and store the phase demodulation information. Therefore, even when the minimum phase inversion interval is one carrier, C /
The phase modulation information can be detected N times well, and the discharge time of the integration circuit can be sufficiently obtained.

According to the fifth aspect of the present invention, since the integration timing and the sample timing of the integration circuit are variable at an integral multiple of the carrier wave period, the length of the phase information (the number of carrier waves forming the unit information) is synchronized. A highly reliable demodulation circuit can be obtained by performing demodulation at an optimal integration and sample timing that differs for each information type and format, such as a difference between a signal and a data signal.

According to the invention of claim 6, since the integration and the sample timing are generated based on the synchronization signal, the use or nonuse of the demodulation circuit can be assigned to each area on the medium. In addition to being able to select the use for areas where high reliability is required or the use of special information that does not include phase inversion in the unit information, the circuit also integrates and samples sequentially every carrier period. If it is performed, a normal demodulation circuit can be used, and selection of use or nonuse can be simplified.

According to the seventh aspect of the present invention, a simple data conversion caused by intermittently changing the integration and the sample timing is returned to the original information. A highly reliable demodulation circuit can be obtained with a simple configuration without changing the modulation rule of the above position data.

According to the invention of claim 8, claim 1, claim 1
4, the effects of claims 1 and 4 are both obtained, and the phase change in the unit information section is eliminated by inverting the phase modulation signal, and the integrated value obtained by accumulating all the phase comparison results is obtained. A higher C / N can be obtained with an increase, and further, a time for discharging the increased integration circuit charging voltage can be sufficiently obtained by sequentially using a plurality of integration circuits.

According to the ninth aspect of the present invention, a simple data conversion caused by inverting the polarity of the phase modulation signal and intermittently changing the integration and the sample timing is converted into the original information. Claims 2 and 7
The demodulation circuits required for each application can be realized by one demodulation circuit.

According to the tenth aspect of the present invention, since the demodulation circuit according to any one of the first to ninth aspects is used as a demodulation circuit of an information recording / reproducing apparatus, an inexpensive and highly reliable apparatus is manufactured. be able to.

[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 a signal waveform of the conventional method.

FIG. 4 is an explanatory diagram of a signal waveform.

FIG. 5 is a block diagram illustrating a configuration example of a demodulation circuit according to a second embodiment of the present invention.

FIG. 6 is an explanatory diagram of the signal waveform.

FIG. 7 is an explanatory diagram of another signal waveform.

FIG. 8 is an explanatory diagram of signal waveforms showing a third embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 6 optical system 7 media 9 light receiving element 11 servo circuit 12 mechanism system 13 reproduction circuit 15 demodulation circuit 21 carrier wave reproduction circuit 22 polarity change circuit 23 inversion signal generation circuit 24 synchronous detection circuit 26 first conversion circuit 31, 32 integration circuit 33, 34 sample circuit 35 second conversion circuit

Claims (10)

[Claims] 1. A demodulation circuit for detecting position data on a medium recorded by wobbling of a track by using a two-phase modulation method for forming unit information including a phase inversion, comprising: A carrier recovery circuit for detecting a carrier from the obtained phase modulation signal; a synchronous detection circuit for comparing the phase of the carrier with the phase modulation signal; and an inversion signal for outputting an inversion signal in accordance with an inversion timing of the phase of the unit information. A generating circuit, and a polarity changing circuit for inverting the polarity of the phase modulation signal in accordance with the inversion signal, detecting phase demodulation information from an output signal level of the synchronous detection circuit, and detecting position data on the medium. A demodulation circuit designed to be obtained. 2. A medium according to claim 1, further comprising a first conversion circuit having data conversion and inverse conversion characteristics of phase demodulation information generated by inverting the polarity of the phase modulation signal, and outputting from the output of the first conversion circuit on the medium. 2. The demodulation circuit according to claim 1, wherein position data is obtained. 3. The apparatus according to claim 1, wherein the position data comprises a synchronization signal and a data signal of an information sequence different from the synchronization signal, and the inverted signal generation circuit generates the inverted signal based on the synchronization signal. Or the demodulation circuit according to 2. 4. A demodulation circuit for detecting position data on a medium recorded by wobbling of a track using a phase modulation method, wherein the carrier reproduction circuit detects a carrier from a phase modulation signal obtained from the medium. A synchronous detection circuit that compares the phase modulation signal with the phase of the carrier; a plurality of integration circuits that integrate output signals of the synchronous detection circuit at different timings; and a sample circuit that sequentially samples an output of the integration circuit. A demodulation circuit configured to detect phase demodulation information from an output signal level of the sample circuit and obtain position data on the medium. 5. The demodulation circuit according to claim 4, wherein an integration timing of said integration circuit and a sampling timing of said sampling circuit are variable at an integral multiple of a period of said carrier wave. 6. The position data according to claim 4, wherein the position data comprises a synchronization signal and a data signal of an information sequence different from the synchronization signal, and the integration timing and the sample timing are generated based on the synchronization signal. Demodulation circuit. 7. A second conversion circuit having a data conversion and inverse conversion characteristic of phase demodulation information generated by intermittently changing the integration timing and the sample timing, and an output of the second conversion circuit. 7. The demodulation circuit according to claim 4, wherein position data on said medium is obtained from the data. 8. A demodulation circuit for detecting position data on a medium recorded by wobbling of a track by using a two-phase modulation method for forming unit information including a phase inversion, wherein the demodulation circuit obtains the position information from the medium. A carrier recovery circuit for detecting a carrier from the obtained phase modulation signal; a synchronous detection circuit for comparing the phase of the carrier with the phase modulation signal; and an inversion signal for outputting an inversion signal in accordance with an inversion timing of the phase of the unit information. A generating circuit, a polarity changing circuit that inverts the polarity of the phase modulation signal in accordance with the inversion signal, a plurality of integration circuits that integrate output signals of the synchronous detection circuit at different timings, and sequentially output the integration circuit. A sample circuit for sampling, detecting phase demodulation information from an output signal level of the sample circuit, and calculating position data on the medium. Demodulation circuit that was to so that. 9. A third device having a data conversion and reverse conversion characteristic of phase demodulation information generated by inverting the polarity of the phase modulation signal and intermittently changing the integration timing and the sample timing. 9. The demodulation circuit according to claim 8, further comprising a conversion circuit, wherein the position data on the medium is obtained from an output of the third conversion circuit. 10. An optical system for converging a light beam on a medium and condensing reflected light 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 for detecting the position data of the 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 An information recording / reproducing apparatus comprising: a system for detecting position data on the medium using the demodulation circuit according to any one of claims 1 to 9.