JP2001126413A - Demodulation circuit and information recording and reproducing device using the circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a demodulation circuit capable of appropriately performing the detection of a phase deviation and the correction of the deviation and accurately performing demodulation. SOLUTION: This circuit is provided with a carrier wave generation circuit 18 for detecting the carrier waves of wobbling signals obtained from a medium and a phase adjustment circuit 24 for generating phase comparison signals provided with the phase difference of 90 deg. with the output signals of the carrier wave generation circuit 18 and capable of finely adjusting a phase. By detecting the phase difference based on the multiplied result by a multiplier 20 of the phase comparison signals and the wobbling signals, even in the case that a difference is generated in the delay amount of a carrier wave detection system and a wobbling signal detection system such as the case that a frequency is changed, the phase deviation of the carrier waves and the wobbling signals is detected.

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-ReWr)
The present invention relates to an information recording / reproducing device for a medium such as a disk and a demodulation circuit used for address demodulation in the device.

[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 (constant linear velocity) rotation control is performed. Therefore, the information recording / reproducing apparatus for the medium detects the wobbling signal to control the rotation of the medium and generate a recording clock. Also, address information is required so that a recording position in an unrecorded area can be specified.
For example, as disclosed in Japanese Patent Application Laid-Open No. H10-69646, a method of performing phase modulation on the wobble of the track described above has been considered. 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. Since the optical disk has poor signal quality obtained from the medium, a binary phase modulation method (BPSK or DPSK, binary modulation of 0 ° and 180 °) that can obtain a relatively high S / N is most suitable.

A circuit for demodulating the phase-modulated address information (wobbling signal) is disclosed in Japanese Patent Publication No. Hei 6-1989.
No. 8, Japanese Patent Laid-Open No.
There is a digital system disclosed in Japanese Patent No. 260413. These generate a carrier wave on which the phase information is superimposed on the basis of the wobbling signal by a subsequent PLL or the like,
The phase difference between the two (0 ° or 180 ° in the case of BPSK) is detected, and the information is demodulated. However, when a phase shift occurs between the original carrier component of the wobbling signal and the carrier generated by the PLL, the performance of the phase demodulation is reduced and erroneous detection frequently occurs.

[0004]

These prior arts are systems used in the field of cameras and communications, and have the following problems with optical discs.

In an optical disc, only a very low signal quality can be obtained in an area after data recording. For this reason, after passing the wobbling signal through a filter such as a BPF, a carrier wave required for demodulation is generated from a signal generated by a PLL or the like based on the signal. This filter has a configuration in which a phase change (delay) is easily generated in order to efficiently remove a phase modulation component and a noise component which are disturbances. In addition, when an optical disk accesses a medium at a CAV (constant angular velocity) rotation, the carrier frequency of the wobbling signal changes at a radial position, so that the phase change (delay) by the above-described filter is performed.
Is particularly likely to occur. Since this phase change causes a phase shift between the original carrier component of the wobbling signal and the generated carrier, the detection accuracy is deteriorated as described above.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a demodulation circuit capable of properly detecting a phase shift and correcting the shift and demodulating with high accuracy, and an information recording / reproducing apparatus using the same.

[0007]

According to a first aspect of the present invention, there is provided a demodulation circuit for detecting position information on a medium recorded by wobbling of a track using a two-phase modulation method. A carrier generation circuit for detecting a carrier of a wobbling signal obtained from the medium; and a phase adjustment for generating a phase comparison signal having a phase difference of 90 ° from an output signal of the carrier generation circuit and capable of finely adjusting the phase. A circuit for performing a multiplication process of the wobbling signal and the phase comparison signal, wherein a phase difference between the wobbling signal and the phase comparison signal is detected from an output level of the multiplier.

Accordingly, since the phase difference is detected based on the multiplication result of the phase comparison signal having a phase difference of 90 ° from the carrier and the wobbling signal, the carrier detection system and the wobbling signal detection system are used when the frequency changes. , It is possible to detect a phase shift between the carrier and the wobbling signal. In particular, a digital circuit can be easily configured.

According to a second aspect of the present invention, in the demodulation circuit according to the first aspect, a low band detector connected to an output side of the multiplier is provided, and the phase difference is detected by the low band detector. The detection is performed based on the detected low-frequency component of the output signal of the multiplier.

[0010] Therefore, the phase difference is detected by 90 degrees from the carrier.
Since the detection is performed based on the low-frequency component of the multiplier output of the phase comparison signal having the phase difference of ° and the wobbling signal, the phase shift can be detected with the simplest circuit configuration.

The invention according to claim 3 is the demodulation circuit according to claim 1 or 2, further comprising an integrator connected to the output side of the multiplier, wherein the phase difference is detected by the integrator. This is performed based on the integration result of the output signal of the multiplier.

Therefore, the detection of the phase difference is performed by detecting 90 degrees from the carrier wave.
Since the detection is performed based on the integration result of the multiplier output of the phase comparison signal having the phase difference of ° and the wobbling signal, it is possible to detect the phase shift with high detection accuracy with a simple configuration.

According to a fourth aspect of the present invention, in the demodulation circuit of the first, second or third aspect, an amplitude detection circuit for detecting an amplitude of the wobbling signal and a gain for reaching a preset target amplitude are calculated. An amplitude adjusting circuit for multiplying the phase comparison signal by the gain.

Accordingly, the amplitude of the wobbling signal is detected, and a gain that reaches a preset target amplitude is calculated.
Since the gain is multiplied by the phase comparison signal, especially in the case of a digital circuit, the phase shift can be detected stably without using an AGC circuit for keeping the amplitude of the wobbling signal constant.

According to a fifth aspect of the present invention, there is provided a demodulation circuit for detecting position information on a medium recorded by wobbling of a track by using a two-phase modulation method. A carrier generation circuit for detecting a carrier of the wobbling signal, a phase adjustment circuit for generating a phase comparison signal capable of finely adjusting the phase based on an output signal of the carrier generation circuit, and a selection signal based on the phase comparison signal at a specific timing A selection signal generation circuit that outputs the wobbling signal and the phase comparison signal, and a switch that turns on and off the output of the subtractor according to the selection signal. The phase difference between the wobbling signal and the phase comparison signal is detected from the output level.

Therefore, the output of the subtractor of the phase comparison signal obtained from the wobbling signal and the carrier wave is turned on / off by the selection signal generated based on the phase comparison signal, so that the position of the wobbling signal and the phase comparison signal is changed. Since the phase difference is detected, the phase shift between the carrier and the wobbling signal can be detected even when a difference occurs in the amount of delay between the carrier detection system and the wobbling signal detection system such as when the frequency changes. Further, in the analog system, there is no need to generate an analog signal having a 90 ° phase difference from a carrier wave which requires a large-scale circuit.

According to a sixth aspect of the present invention, in the demodulation circuit according to the fifth aspect, an integrator connected to an output side of the switch is provided, and the phase difference is detected by the integrator detected by the integrator. It was based on the result.

Therefore, by detecting the phase shift based on the integration result of the output of the switch, it is possible to detect the phase shift with high detection accuracy with a simple configuration.

According to a seventh aspect of the present invention, there is provided a demodulation circuit for detecting position information on a medium recorded by wobbling of a track using a two-phase modulation method, wherein the demodulation circuit is obtained from the medium. A carrier generation circuit for detecting a carrier of the wobbling signal, a phase adjustment circuit for generating a phase comparison signal capable of finely adjusting the phase based on an output signal of the carrier generation circuit, and a selection signal based on the phase comparison signal at a specific timing A subtractor for performing a subtraction operation between the wobbling signal and the phase comparison signal; an inverting circuit for inverting an output signal of the subtractor; an output of the subtractor and an output of the inverting circuit A selector for selecting the wobbling signal and the phase comparison signal from the output level of the selector. And to detect the difference.

Therefore, the subtraction operation result of the phase comparison signal obtained from the wobbling signal and the carrier wave and the inversion result thereof are expressed as follows:
Since the phase difference between the wobbling signal and the phase comparison signal is detected by the output selected by the selection signal generated based on the phase comparison signal, the delay between the carrier detection system and the wobbling signal detection system such as when the frequency changes. Even when a difference occurs in the amount, a phase shift between the carrier and the wobbling signal can be detected. Since the sensitivity of the detection signal is doubled as compared with the case of the fifth aspect, stable detection is also possible. Further, in the analog system, there is no need to generate an analog signal having a 90 ° phase difference from a carrier wave which requires a large-scale circuit.

The invention according to claim 8 is the demodulation circuit according to claim 7, further comprising an integrator connected to the output side of the selector, wherein the phase difference is detected by the integrator. Is performed based on the integration result of the output.

Therefore, the phase shift detection is performed based on the integration result of the output of the selector, so that the phase shift can be detected with high detection accuracy with a simple configuration.

The ninth aspect of the present invention provides the first to eighth aspects.
In the demodulation circuit according to any one of the above, the wobbling signal is controlled to have a constant amplitude.

Therefore, since the wobbling signal controlled to have a constant amplitude is used, the level of the phase shift detection signal does not change according to the amplitude, and the phase shift can be detected with high accuracy.

According to a tenth aspect of the present invention, in the demodulation circuit according to any one of the first to ninth aspects, the phase difference is detected in a specific area in a wobble phase modulation format.

Therefore, since the phase difference is detected at a specific position in the wobble phase modulation format, even if the detection method is such that the level of the phase shift detection signal is affected by the phase modulation data, the phase difference is kept constant. A stable phase shift amount can be detected based on the modulation data influence degree.

According to an eleventh aspect of the present invention, in the demodulation circuit according to the tenth aspect, the specific area is an area where a phase does not change in a wobble phase modulation format.

Therefore, since the phase difference is detected in a region where the phase does not change in the wobble phase modulation format, there are many choices of the detection signal, and the phase shift can be detected with a simple circuit configuration. Further, in the phase modulation, since there are many regions where a phase change does not occur due to generation of a carrier, the timing at which a phase shift can be detected is also abundant.

According to a twelfth aspect of the present invention, in the phase demodulation circuit according to any one of the first to eleventh aspects, the phase adjustment circuit adjusts the phase comparison signal so that the detected phase difference becomes zero. Control the phase.

Therefore, the phase of the phase adjustment circuit is controlled so that the phase difference detected by the phase difference detection processing by the demodulation circuit according to any one of claims 1 to 11 becomes zero, so that the carrier wave that dynamically changes is controlled. And a system that automatically follows the delay amount difference between the wobbling signal and the wobbling signal.

An information recording / reproducing apparatus according to claim 13, wherein an optical system for condensing a light beam on a medium and condensing light reflected from the medium on a light receiving element, and 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 Claim 12
The position data on the medium is detected using the demodulation circuit described above.

Therefore, since the demodulation circuit of the twelfth aspect is used as the demodulation circuit of the information recording / reproducing apparatus, the adjustment step can be omitted, and an inexpensive and highly reliable apparatus can be manufactured.

[0033]

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 reflected light from the recording surface 7a returns to the optical system 6 again, and
And 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 a current into a voltage by the I / V amplifier 10 and various calculations are performed. However, the calculation may be performed without changing the current. Normally, light receiving element
The I / V amplifier 9 and the I / V amplifier 10 are divided into a plurality of parts. A focus error signal indicating the distance between the medium surface and the focal point of the light spot, a track error signal indicating the position of the track and the light spot on the medium surface, and the medium 7 Recording surface 7
An operation such as an RF signal for detecting information recorded on a is performed. 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. The 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 should be noted that the wobbling signal used in this embodiment and each embodiment described later is obtained from a reproduced signal because the detection method differs depending on the divisional shape of the light receiving element 9, but the simplest is described. An example is a case where detection is performed from a push-pull signal (one of the track error signals) obtained from the difference between the left and right of the light-receiving element dividing line along the track. Therefore, in the following description, the push-pull output from the servo circuit 11 is used. The description will be made on the assumption that the demodulation circuit 15 operates based on the signal. Here, the demodulation circuit 15 is characteristically configured for each embodiment.

First, in order to extract the phase modulation component from the wobbling signal obtained from the optical system 6, it is necessary to generate a carrier wave which is not modulated at the same frequency and phase as 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 demodulated signal waveform diagram shown in FIG.

First, a BPF (Band Pass Filter) is used to remove noise and phase modulation components from the wobbling signal.
A carrier signal is generated using a carrier generation circuit 18 including 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. On the other hand, the wobbling signal is passed through an LPF (low-pass filter) 19 to remove only a noise component, and a multiplier 20 performs a multiplication operation on the carrier signal. The output signal from the multiplier 20 is converted to a low-frequency detector 21 (phase shift A), an integrator 22 (phase shift B), or a low-frequency detector 23 (phase shift) that obtains a low-frequency component of the output signal of the integrator 22. C) to obtain phase demodulation information for detecting a phase shift.

FIG. 3 shows the phase modulated wobbling signal, the carrier signal, the output of the multiplier 20 and the output of the low band detector 21. As can be seen by comparing the outputs, the phase modulation information is reproduced. The basic phase demodulation operation is as described above.

In addition to the basic configuration and operation of the phase demodulation, a characteristic configuration and operation according to the present embodiment will be described with reference to FIGS.
2, 3, 12, and 13).

In the present embodiment, a phase adjustment circuit 24 is added to detect a phase shift between the carrier signal generated by the carrier generation circuit 18 and the wobbling signal. The BPF 16 that removes a noise component and a phase modulation component included in the wobbling signal easily changes its phase depending on the frequency. Therefore, the carrier signal generated from the signal passing through the BPF 16 and the LPF 1 having a small phase change
A phase difference occurs between the wobbling signals passing through only 9 lines. Therefore, the phase adjustment circuit 24 generates a phase comparison signal having a phase different from the carrier signal by 90 °. Assuming that the carrier signal is a sine wave (sine wave), the phase comparison signal has a relationship of a cosine wave (cosine wave). In the case of an analog circuit configuration, it may be easier to design the phase adjustment circuit 24 in the circuit of the PLL 17 in some cases. When the phase comparison signal and the wobbling signal passed through the LPF 19 are multiplied by the multiplier 20, a signal that changes according to the phase shift 90 + α degrees α is obtained from the multiplication result. The phase shift α is the same as the phase shift between the generated carrier signal and the wobbling signal.

FIGS. 4 and 5 show examples of this signal waveform. FIG. 4 shows a case where there is no phase shift, and FIG. 5 shows a case where there is a phase shift. Here, the signals shown in these figures are: PMin: after LPF of the wobbling signal (left axis) cos: phase comparison signal (left axis) Mpy x: multiplier output (left axis) ave x: multiplier output Low frequency component (left axis) Int x: Integration result of multiplier output (right axis).

From FIG. 4, when there is no phase shift, that is, since the phase difference between the wobbling signal after the LPF 19 and the phase comparison signal is 90 °, the low-frequency component ave is at the 0 level and the integration result Int is at the specific level. Go up and down to the standard. But,
In the case where there is a phase shift as shown in FIG.
To a certain level on the plus side, and the integration result Int increases steadily. If the polarity of the phase shift is opposite,
The low-frequency component ave is on the minus side, and the integration result Int is in the decreasing direction. As a ave detection circuit, a low-pass detector 2 such as an LPF for detecting a low-pass component of the output of the multiplier 20 is used.
As an example of the Int detection circuit, there is an integrator 22 for integrating the output of the multiplier 20. It is also effective to use a low-frequency detector 23 for detecting a low-frequency component of the output of the integrator 22.

Then, the phase adjustment circuit 24 finely controls the phase of the phase comparison signal so that the detected phase difference becomes zero. That is, by controlling the phase of the phase adjustment circuit 24 so that the detected phase difference becomes 0, a system that automatically follows the dynamically changing delay amount difference between the carrier signal and the wobbling signal is provided. Can be built.

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). This embodiment corresponds to claims 5 to 8.

In this embodiment, the phase adjustment circuit 2
5 is a circuit that outputs a phase comparison signal that can finely adjust the phase of the carrier signal generated by the carrier generation circuit 18 around 0 °. That is, if the carrier signal is a sine wave, the phase comparison signal is also a sine wave. The difference between the wobbling signal passed through the LPF 19 and the phase comparison signal to detect a phase shift is subtracted by a subtracter 26.
Ask for. The polarity of the output of the subtracter 26 is further inverted by an inversion circuit 27. The selection signal generation circuit 28 converts a selection signal (corresponding to a binarized signal of a cos wave) indicating a section corresponding to a phase of 90 ° to 270 ° based on the phase comparison signal into a selector 29 (or a switch (not shown)). ). In the case of a switch (not shown), the output of the subtractor 26 is turned on / off in accordance with the selection signal. In the case of the selector 29, the output of the subtractor 26 and the output of the inverting circuit 27 are switched. The output of the selector 29 (or switch) is a signal indicating the phase shift α between the carrier signal and the wobbling signal, and is output by the low-pass detector 30 (phase shift D) and the integrator 31 (phase shift E) at the subsequent stage. The signal level is set according to the phase shift.

FIGS. 7 and 8 show waveform examples for detecting the phase shift. FIG. 7 shows a state without a phase shift, and FIG. 10 shows a state with a phase shift. Here, the signals shown in these figures are as follows: PMin: after LPF of the wobbling signal (left axis) sin: phase comparison signal (left axis) sub: selector output (left axis) sel: selection signal (numerical value is irrelevant) , H / L only) Int x: Integration result of selector output (right axis).

As shown in FIG. 7, when there is no phase shift, the output of both the selector output sub and the integration result Int is 0. When there is a phase shift, the output of the subtractor 26 is negative on the phase comparison signal 90 ° to 270 °, and 0 ° to 90 ° and 27 °.
In the range of 0 ° to 360 °, the signal is output on the plus side (the reverse is also possible). Depending on the selection signal, 90 °
At 270 °, the output of the inverting circuit 27 is selected and a signal converted to the plus side is output, and 0 ° to 90 ° and 270 ° to 360 ° are output.
In the case of °, the output of the subtracter 26 is selected as it is and output to the subsequent circuit. This is shown in FIG. When a switch is used in place of the selector 29, only half the phase comparison (only the output of the subtractor 26) is performed, so that the signal level is reduced by half compared with the selector 29 method. As a circuit at the subsequent stage of the selector 29 or the switch output, a low band detector 30 such as an LPF for detecting a low band of a sub signal and an integrator 31 for detecting an Int signal may be used.

A third embodiment of the present invention will be described with reference to FIG. This embodiment corresponds to the fourth and ninth aspects of the present invention.

As described above, the phase shift is detected based on the output levels of the multiplier 20 and the subtractor 26.
This level changes depending on the amplitude of a wobbling signal or a phase comparison signal which is an input signal. Generally, the carrier is controlled to have a constant amplitude. However, since the wobbling signal is a signal detected from the medium 7, an amplitude change occurs. For this reason, it is preferable to mount an AGC circuit for controlling the amplitude of the wobbling signal at a constant level before the demodulation circuit 15. Of course, in order to suppress the amplitude fluctuation after passing through the LPF 19,
The signal after the LPF may be kept constant.

Further, the amplitude of the wobbling signal is detected,
The amplitude of the phase comparison signal may be changed. This method can be easily realized when a digital circuit is used. This block diagram is shown in FIG. The wobbling signal is digitized by an ADC (analog-digital converter) 32. Also, as in the case described above, the carrier generation circuit 1
At 8, a carrier signal is generated. The carrier signal is ADC
It may be generated from a wobbling signal that has already been binarized, instead of the output of the wobbling signal. Since the carrier signal is generated by a digital circuit, the carrier signal is a binary signal. The sine wave data is stored in the ROM 33 in order to output the sine wave shape of the wobbling signal as a phase comparison signal. Normally, the data of the ROM 33 is output at a timing controlled by the output of the phase adjustment circuit 24 and the output of the counter 34, thereby forming a phase comparison signal. The digital wobbling signal and the phase comparison signal thus generated can be subjected to the operation of detecting a phase shift by the multiplier 20 and the subtractor 26 in the same manner as described above. Here, the amplitude of the wobbling signal is detected by the amplitude detection circuit 35 based on the data fetched by the ADC 32, and a difference from a preset target amplitude is obtained as a gain. The gain may be multiplied by the data in the ROM 33, and the result may be stored in the RAM 36 and output from the RAM 36 as a phase comparison signal. This R
The portion constituted by the OM 33 and the RAM 36 is the amplitude adjustment circuit 37. In addition, the phase adjustment circuit 24 generates a phase comparison signal in which a phase shift of 0 ° or 90 ° is generated based on the carrier signal. In this digital configuration, the phase comparison circuit 24 simply changes the start address of the counter 34. It is also possible to cause a phase shift.

A fourth embodiment of the present invention will be described with reference to FIGS. This embodiment relates to claim 10
And 11.

The phase modulation format is usually divided into a synchronization area including a special pattern for synchronizing, a data area including address information and the like, and a constant phase area for performing carrier wave pull-in (see FIG. 3). ). In the data area, phase modulation data cannot be predicted.
It is difficult to obtain the effects of the present invention. FIGS. 10 and 11 show waveform changes at the phase change point (for 2 wobbles) in the case of the fourth embodiment. FIG. 10 shows a case without a phase shift, and FIG. 11 shows a case with a phase shift. The first half wobble has the same phase relationship as in the second embodiment, but the second half wobble has a PMin signal that is 180 ° out of phase with the carrier wave, so that the opposite phase shift detection characteristic appears. For this reason, ave is 0 as in the case where there is no phase shift.
Becomes Int has the same value for the last value of 2 wobbles with or without a phase shift, but the low-frequency component of Int (not shown, but can be considered as an average) is on the plus side and detects a phase shift. . The same applies to the case of the second embodiment.

From this, since the phase detection value is correlated with the phase modulation data, it is necessary to predict the phase information at the detection point in practicing the present invention. Since the pattern can be predicted in the synchronous region, if the pattern is limited to 2 wobbles, which is a phase change point, the low-frequency detecting circuit 2 for detecting the low-frequency component of Int as described with reference to FIGS.
3, the phase shift can be detected. However, the detection method is simple, and a method that can be expected to be accurate is a method of detecting a phase shift in a constant phase region.

[0054]

According to the demodulation circuit of the present invention, the phase difference is detected based on the multiplication result of the phase comparison signal having a phase difference of 90 ° from the carrier and the wobbling signal. In the case where there is a difference in the amount of delay between the carrier wave detection system and the wobbling signal detection system, such as when the frequency has changed, the phase shift between the carrier wave and the wobbling signal can be detected. it can.

According to the second aspect of the present invention, in the demodulation circuit according to the first aspect, the detection of the phase difference is performed by detecting the phase difference from the carrier wave.
Since it is performed based on the low frequency component of the multiplier output of the phase comparison signal having a phase difference of 0 ° and the wobbling signal,
A phase shift can be detected with the simplest circuit configuration.

According to the third aspect of the present invention, in the demodulation circuit according to the first or second aspect, the phase difference is detected by detecting the output of the multiplier of the phase comparison signal having a phase difference of 90 ° from the carrier and the wobbling signal. Since the detection is performed based on the integration result, it is possible to detect a phase shift with high detection accuracy with a simple configuration.

According to the invention set forth in claim 4, according to claim 1,
In the demodulation circuit described in 2 or 3, the amplitude of the wobbling signal is detected, a gain that reaches a preset target amplitude is calculated, and the gain is multiplied by the phase comparison signal. In the case of a circuit, the phase shift can be detected stably without using an AGC circuit that keeps the amplitude of the wobbling signal constant.

According to the demodulation circuit of the fifth aspect,
A phase difference between the wobbling signal and the phase comparison signal is detected by an output obtained by turning on / off a subtractor output of the phase comparison signal obtained from the wobbling signal and the carrier by a selection signal generated based on the phase comparison signal. Because it was
Even if there is a difference in the amount of delay between the carrier wave detection system and the wobbling signal detection system, such as when the frequency changes, the phase shift between the carrier wave and the wobbling signal can be detected. It is not necessary to generate an analog signal having a 90 ° phase difference from the required carrier.

According to the sixth aspect of the present invention, in the demodulation circuit according to the fifth aspect, the phase shift is detected based on the integration result of the output of the switch. Can be detected.

According to the demodulation circuit of the present invention,
A phase difference between the wobbling signal and the phase comparison signal is detected based on an output selected by a selection signal generated based on the phase comparison signal and a result of the subtraction operation of the phase comparison signal obtained from the wobbling signal and the carrier and the inversion result thereof. Therefore, even when a difference occurs in the amount of delay between the carrier detection system and the wobbling signal detection system, such as when the frequency changes,
In addition to being able to detect the phase shift between the carrier and the wobbling signal, the sensitivity of the detection signal is doubled as compared with the case of the invention described in claim 5, so that stable detection is also possible. In the analog system, there is no need to generate an analog signal having a 90 ° phase difference from a carrier wave that requires a large-scale circuit.

According to the eighth aspect of the present invention, in the demodulation circuit according to the seventh aspect, the phase shift detection is performed based on the integration result of the output of the selector. Can be detected.

According to the ninth aspect of the present invention, in the demodulation circuit according to any one of the first to eighth aspects, the wobbling signal controlled to have a constant amplitude is used. Highly accurate phase shift detection can be performed without changing the level of the shift detection signal.

According to the invention of claim 10, according to claim 1,
In the demodulation circuit according to any one of the first to ninth aspects, the phase difference is detected at a specific position on the wobble phase modulation format, so that the level of the phase shift detection signal is affected by the phase modulation data. Even with this method, a stable phase shift amount can be detected with a constant degree of phase modulation data influence.

According to the eleventh aspect, according to the first aspect,
In the demodulation circuit described in No. 0, the phase difference is detected in a region where the phase does not change on the wobble phase modulation format, so that there are many choices of the detection signal, and the phase shift can be detected with a simple circuit configuration. Further, in the phase modulation, since there are many regions in which a phase change does not occur due to generation of a carrier, the timing at which a phase shift can be detected is also abundant.

According to the twelfth aspect, the first aspect
In the phase demodulation circuit according to any one of claims 11 to 11,
12. The delay of a dynamically changing carrier wave and a wobbling signal because the phase of the phase adjustment circuit is controlled so that the phase difference detected by the phase difference detection processing by the demodulation circuit according to claim 1 becomes zero. A system that automatically follows the difference in volume can be constructed.

According to the information recording / reproducing apparatus of the present invention, the demodulation circuit of the information recording / reproducing apparatus can be used as a demodulating circuit.
Since the demodulation circuit described in No. 2 is used, the adjustment step can be omitted, and an inexpensive and highly reliable device can be manufactured.

[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 a waveform diagram showing a basic demodulated signal example of a demodulation operation.

FIG. 4 is a signal waveform diagram when there is no phase shift.

FIG. 5 is a signal waveform diagram when there is a phase shift.

FIG. 6 is a block diagram illustrating a configuration example of a demodulation circuit according to a second embodiment of the present invention.

FIG. 7 is a signal waveform diagram when there is no phase shift.

FIG. 8 is a signal waveform diagram when there is a phase shift.

FIG. 9 is a block diagram illustrating a configuration example of a demodulation circuit according to a third embodiment of the present invention.

FIG. 10 is a signal waveform diagram in the case where there is no phase shift according to the fourth embodiment of the present invention.

FIG. 11 is a signal waveform diagram when there is a phase shift.

[Explanation of symbols]

 Reference Signs List 6 optical system 7 medium 9 light receiving element 11 servo circuit 12 mechanism system 13 reproduction circuit 15 demodulation circuit 18 carrier wave generation circuit 20 multiplier 21 low band detector 22 integrator 24, 25 phase adjustment circuit 26 subtracter 27 inversion circuit 28 selection signal Generation circuit 29 Selector 31 Integrator 35 Amplitude detection circuit 37 Amplitude adjustment circuit

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5D029 WA02 WA16 WD13 5D044 BC06 CC04 DE37 GL02 GL38 GM15 5D090 AA01 BB04 CC04 GG01 GG27

Claims (13)

[Claims] 1. A demodulation circuit for detecting position information on a medium recorded by wobbling of a track by using a two-phase modulation method, wherein a carrier wave for detecting a carrier wave of a wobbling signal obtained from the medium is provided. A phase adjustment circuit for generating a phase comparison signal having a phase difference of 90 ° with the output signal of the carrier generation circuit and capable of finely adjusting the phase; a multiplication process of the wobbling signal and the phase comparison signal A demodulator that detects a phase difference between the wobbling signal and the phase comparison signal from an output level of the multiplier. 2. A low-pass detector connected to an output side of the multiplier, wherein the detection of the phase difference is performed based on a low-pass component of an output signal of the multiplier detected by the low-pass detector. The demodulation circuit according to claim 1, wherein the demodulation is performed. 3. The apparatus according to claim 1, further comprising an integrator connected to an output side of said multiplier, wherein said detection of said phase difference is performed based on an integration result of an output signal of said multiplier detected by said integrator. Item 3. The demodulation circuit according to item 1 or 2. 4. An amplitude detecting circuit for detecting an amplitude of the wobbling signal, and an amplitude adjusting circuit for calculating a gain reaching a preset target amplitude and multiplying the gain by the gain. The demodulation circuit according to 1, 2, or 3. 5. A demodulation circuit for detecting position information on a medium recorded by wobbling of a track using a two-phase modulation method, wherein a carrier wave for detecting a carrier wave of a wobbling signal obtained from the medium is provided. A phase adjustment circuit that generates a phase comparison signal whose phase can be finely adjusted based on an output signal of the carrier generation circuit; a selection signal generation circuit that outputs a selection signal at a specific timing based on the phase comparison signal; A subtractor for performing a subtraction operation between the wobbling signal and the phase comparison signal; and a switch for turning on / off an output of the subtractor in accordance with the selection signal. The wobbling signal and the phase are determined based on an output level of the switch. A demodulation circuit for detecting a phase difference from a comparison signal. 6. The apparatus according to claim 5, further comprising an integrator connected to an output side of the switch, wherein the detection of the phase difference is performed based on an integration result of the output of the switch detected by the integrator. Demodulation circuit. 7. A demodulation circuit for detecting position information on a medium recorded by wobbling of a track using a two-phase modulation method, wherein a carrier wave for detecting a carrier wave of a wobbling signal obtained from the medium is provided. A phase adjustment circuit that generates a phase comparison signal whose phase can be finely adjusted based on an output signal of the carrier generation circuit; a selection signal generation circuit that outputs a selection signal at a specific timing based on the phase comparison signal; A subtractor that performs a subtraction operation of the wobbling signal and the phase comparison signal; an inverting circuit that inverts an output signal of the subtractor; and a selector that selects an output of the subtractor and an output of the inverting circuit by the selection signal. Wherein the phase difference between the wobbling signal and the phase comparison signal is detected from the output level of the selector. Circuit. 8. The apparatus according to claim 7, further comprising an integrator connected to an output side of said selector, wherein said phase difference is detected based on an integration result of an output of said selector detected by said integrator. Demodulation circuit. 9. The demodulation circuit according to claim 1, wherein the wobbling signal is controlled to have a constant amplitude. 10. The demodulation circuit according to claim 1, wherein the phase difference is detected in a specific area on a wobble phase modulation format. 11. The demodulation circuit according to claim 10, wherein the specific area is an area where a phase does not change in a wobble phase modulation format. 12. The phase demodulation circuit according to claim 1, wherein the phase adjustment circuit controls the phase of the phase comparison signal so that the detected phase difference becomes zero. 13. 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 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: detecting position data on the medium using the demodulation circuit according to claim 12.