JP3720197B2 - Phase comparator - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is used in a recording clock signal generator for generating a recording clock signal in an information recording apparatus for recording information on a recordable optical disk based on a recording clock signal synchronized with the rotation of the optical disk. The present invention relates to a phase comparison device.
[0002]
[Prior art]
A CD-R (Compact Disc-Recordable) is known as a recordable optical disc that can be recorded only once.
[0003]
CD-R slightly wobbles in the disk radial direction according to the wobble signal obtained by FM-modulating a carrier wave having a predetermined frequency (22.05 KHz) with pre-information such as track position information on the disk. There are recorded groove tracks (information recording tracks).
[0004]
In order to extract a wobble signal from such a groove track, the reflected light from the groove track of the irradiated light beam is received by a photodetector divided into two by a dividing line optically parallel to the tangential direction of the groove track, and each detector is detected. This is done by taking the difference in the output from and supplying the difference signal to a BPF (Band Pass Filter) having the predetermined frequency as the center frequency.
[0005]
The CD-R is rotationally controlled so that the average frequency of the wobble signal extracted via the BPF becomes the predetermined frequency. At this time, the extracted wobble signal (hereinafter referred to as the extracted wobble signal) is also used as a reference signal for generating a recording clock signal. That is, the extracted wobble signal is a continuous signal having a frequency component synchronized with the rotation of the disk, and a clock signal for recording that is accurately synchronized with the rotation of the disk by generating a clock signal that is phase-synchronized with the continuous signal. Is generated.
[0006]
[Problems to be solved by the invention]
Recently, research and development on a so-called DVD-R (Digital Versatile Disc-Recordable) has been actively conducted as an information recording medium having a recording capacity improved by about 7 times compared to a conventional CD-R.
[0007]
In the DVD-R, in order to perform high density recording, the pitch between adjacent tracks is approximately half that of the CD-R. For this reason, leakage from a groove track adjacent to the groove track irradiated with the light beam, so-called crosstalk, cannot be ignored. If there is crosstalk from the adjacent left and right groove tracks, the extracted wobble signal will be interfered by the wobble signal component of the adjacent groove track, and the amplitude and phase will fluctuate. In particular, there is a problem that a clock signal that is accurately synchronized with the rotation of the disk cannot be generated from the extracted wobble signal affected by the crosstalk due to phase fluctuation, that is, jitter.
[0008]
That is, when a fluctuation occurs in the rotation control signal (phase difference between the reference signal and the extracted wobble signal) due to crosstalk or the like, the time required for establishing the rotation control in response to the rotation control signal, and the clock signal Since the time required to establish the PLL circuit that generates the signal is different (usually the response of the rotation control is much slower than the response of the PLL circuit due to the inertia of the disk), the phase of the clock signal and the rotation phase of the disk Will be shifted in the meantime. When such a deviation occurs, it becomes impossible to record and form a data pattern to be recorded at a position where recording should be originally performed.
[0009]
Therefore, the clock signal generator is configured to detect the amount of variation between the phase of the extracted wobble signal and the phase inherent in the wobble signal, and to cancel the amount of variation with respect to the generated recording clock signal. However, for this purpose, a phase comparison device capable of accurately detecting the variation amount is required.
[0010]
The present invention has been made in view of the above problems, and its purpose is to be able to accurately detect the fluctuation amount of the extracted wobble signal with respect to the original phase due to the influence of crosstalk from adjacent groove tracks. An object of the present invention is to provide a phase comparison device.
[0011]
[Means for Solving the Problems]
  In order to solve the above problem, the invention described in claim 1 includes an information recording track wobbled by a wobble signal having a predetermined frequency, and a guide track for guiding a recording beam to the information recording track, The guide track is formed with a predetermined phase relationship with respect to the wobble signal.RupuA phase comparison device for comparing phases of the wobble signal and the prepit in an information recording apparatus for recording information on an optical disc having a repit, the wobble signal extracting means for extracting the wobble signal, and the prepit Pre-pit detecting means for detecting, and monotonous for a period of a period synchronized with the extracted wobble signal and corresponding to the predetermined frequencychangePeriodic signal generating means for generating periodic signals, and holding means for latching the amplitude level of the periodic signals at the detection timing of the prepits;Averaging means for averaging the latched amplitude levels;It is comprised with.
[0013]
  According to the phase comparison apparatus of the present invention, the information recording track wobbled by a wobble signal having a predetermined frequency, the guide track for guiding the recording beam to the information recording track, and further on the guide track Is formed with a predetermined phase relationship to the wobble signalRupuIn detecting the rotational phase of the disc at the time of recording information on an optical disc having a repit, the phase of the extracted wobble signal and the prepit detection signal that detects the prepit is compared.
[0015]
  Here, the pre-pit signal is recorded with a predetermined phase relationship with the wobble signal.
  Therefore, even if the time axis of the extracted wobble signal in the desired groove track fluctuates due to crosstalk due to the wobble signal of the adjacent groove track, the extraction is performed by comparing the phase of the extracted wobble signal with the phase of the prepit detection signal. It is possible to accurately detect the fluctuation amount of the wobble signal with respect to the inherent phase, and consequently, it is possible to generate a recording clock signal that is accurately synchronized with the rotation of the disk.In particular, when the prepit signal does not exist in the adjacent land track position on the same straight line in the disc radial direction, the prepit signal can be detected without being affected by the crosstalk caused by the adjacent prepit.
[0016]
Even if the prepit signal is erroneously detected due to noise or the like, averaging is performed when the phase adjustment signal is generated by comparing the phase of the extracted wobble signal extracted from the groove track and the prepit detection signal. Therefore, it is possible to reduce the influence of erroneous detection of the prepit signal and to perform phase comparison with high accuracy.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Next, preferred embodiments of the present invention will be described with reference to the drawings.
First, a DVD-R as an optical disk in which pre-pits corresponding to pre-information are formed and a groove track described later is wobbled at a predetermined frequency will be described with reference to FIGS.
[0018]
First, the structure of the DVD-R will be described with reference to FIG.
In FIG. 1, a DVD-R 31 is a dye-type DVD-R having a dye film 35 as a data recording layer and capable of writing information data only once, and a groove track 32 as an information recording track and the groove track 32. Further, a land track 33 as a guide track for guiding a light beam B such as a laser beam as reproduction light or recording light is formed. Further, a protective film 37 for protecting them and a gold vapor deposition film 36 for reflecting the light beam B when reproducing recorded data are provided. A pre-pit 34 corresponding to the pre-information is formed on the land track 33. This pre-pit 34 is formed in advance before the DVD-R 31 is shipped.
[0019]
Further, in the DVD-R 31, the groove track 32 is wobbled at a frequency corresponding to the rotational speed of the disc. The wobbled groove track 32 is formed in advance before the DVD-R 31 is shipped, like the pre-pit 34.
[0020]
When recording information data (information data such as image information to be originally recorded other than pre-information; the same applies hereinafter) is recorded on the DVD-R 31, the wobbling of the groove track 32 is performed in an information recording apparatus described later. The DVD-R 31 is controlled to rotate at a predetermined rotational speed by extracting the frequency, and pre-information is acquired in advance by detecting the pre-pit 34, and the optimum output of the light beam B as recording light is set based on the pre-information. At the same time, address information indicating the position on the DVD-R 31 where the record information data is to be recorded is acquired, and the record information data is recorded at the corresponding record position based on this address information.
[0021]
Here, when recording the record information data, the light beam B is irradiated so that the center thereof coincides with the center of the groove track 32 to form a record information pit corresponding to the record information data on the groove track 32. Record recording data. At this time, the size of the light spot SP is set so that a part of the light spot SP is irradiated not only on the groove track 32 but also on the land track 33 as shown in FIG.
[0022]
Then, by using a part of the reflected light of the light spot SP irradiated on the land track 33, it is divided by a push-pull method (a dividing line parallel to the tangential direction of the groove track 32, that is, the rotation direction of the DVD-R 31). A push-pull method using a photodetector (hereinafter referred to as a radial push-pull method) detects pre-information from the pre-pit 34 to acquire the pre-information and extracts a wobble signal from the groove track 32 to obtain a disc. A recording clock signal, which will be described later, synchronized with the rotation is acquired.
[0023]
Next, a recording format of pre-information recorded in advance on the DVD-R 31 will be described with reference to FIG. In FIG. 2, the upper row shows the recording format of the recording information data, and the lower waveform shows the wobbling state (plan view of the groove track 32) of the groove track 32 that records the recording information data. An upward arrow during the wobbling state of the track 32 schematically indicates a position where the prepit 34 is formed. Here, in FIG. 2, the wobbling state of the groove track 32 is shown using an amplitude larger than the actual amplitude for easy understanding. The recording information data is recorded on the center line of the groove track 32.
[0024]
As shown in FIG. 2, the record information data recorded on the DVD-R 31 is divided in advance for each sync frame as an information unit. Then, one recording sector is formed by 26 sync frames, and one ECC (Error Correcting Code) block is formed by 16 recording sectors. One sync frame has a length of 1488 times (1488T) a unit length (hereinafter referred to as T) corresponding to a pit interval defined by the recording format when recording the recording information data. Further, the first 32T length portion of one sync frame is used as synchronization information SY for synchronizing each sync frame.
[0025]
On the other hand, the pre-information recorded on the DVD-R 31 is recorded for each sync frame. Here, when pre-information is recorded on the DVD-R 31 by the pre-pit 34, a sync signal in the pre-information is placed on the land track 33 adjacent to the area where the sync information SY in each sync frame in the record information is recorded. As shown, one pre-pit 34 is always formed and two or one pre-information is recorded on the land track 33 adjacent to the first half of the sync frame other than the sync information SY. (In the first half of the sync frame other than the synchronization information SY, the prepit 34 may not be formed depending on the content of the preinformation to be recorded.)
[0026]
At this time, in one recording sector, pre-pits 34 are formed only in even-numbered sync frames (hereinafter referred to as EVEN frames), and pre-information is recorded. That is, in FIG. 2, when the prepit 34 is formed in the EVEN frame (indicated by a solid line upward arrow in FIG. 2), the prepit 34 is not formed in the adjacent ODD frame. The relationship between the presence or absence of each of the prepits 34 (prepits B2, B1, and B0 from the beginning of the sync frame, respectively) in one EVEN frame and the subsequent ODD frame is that the one EVEN frame is the beginning of the recording sector. No, and the content of information to be recorded in the one EVEN frame and the subsequent ODD frame.
[0027]
More specifically, when pre-pits are formed in the EVEN frame, all pre-pits 34 (pre-pits B2, B1, and B0) are formed in the first sync frame of the recording sector, and other than the first of the recording sector. In the sync frame, when the pre-information to be recorded in the sync frame is “1”, pre-pits B2 and B0 are formed, and when the pre-information to be recorded is “0”, only the pre-pit B2 is formed. When pre-pits are formed in an ODD frame, pre-pits B2 and B1 are formed in the first sync frame of the recording sector, and in the sync frames other than the first of the recording sector, the same as in the case of the EVEN frame. It is.
[0028]
Note that which sync frame of the EVEN frame / ODD frame the prepit 34 is formed on depends on the position of the prepit 34 formed in advance on the adjacent land track. That is, the pre-pit 34 is normally formed in the EVEN frame. However, when the pre-pit 34 is formed in the EVEN frame, the pre-pit 34 on the adjacent land track formed in advance and the DVD-R 31 in the radial direction of the disc. When approaching, a pre-pit 34 is formed in the ODD frame. By forming in this way, the pre-pit 34 does not exist in the adjacent land track position, so that the influence of crosstalk can be reduced when detecting the pre-pit 34.
[0029]
On the other hand, the groove track 32 is wobbled at a constant wobbling frequency f0 (frequency at which eight wobble signals are included in one sync frame) over all sync frames. Then, in the information recording apparatus described later, by extracting this constant wobbling frequency f0, a signal for controlling the rotation of the spindle motor is detected and a recording clock signal is generated.
[0030]
In order to make the phase relationship between the prepit 34 and the wobble signal constant, the prepit B2 is formed at a predetermined position (for example, a position separated by 7T) from the start position of the sync frame, and 186T (1488T / 8) from the prepit B2. ) Prepits B1 and B0 are formed separately (the prepit formation method is described in detail in Japanese Patent Application No. 310941).
[0031]
First embodiment of phase comparator
Next, a first embodiment of the phase comparison apparatus according to the present invention included in the information recording apparatus will be described with reference to FIGS. In the following description, an embodiment in which the present invention is applied to an information recording apparatus for recording recording information data transmitted from a host computer onto the DVD-R 31 will be described.
[0032]
First, the overall configuration and operation of the information recording apparatus including the phase comparison apparatus according to this embodiment will be described with reference to FIG. In the following embodiment, in the DVD-R 31, the pre-pit 34 including the address information on the DVD-R 31 and the groove track 32 to be wobbled are formed in advance, and when recording information data is recorded, the pre-pit It is assumed that the address information on the DVD-R 31 is obtained by detecting 34 in advance, and the recording position on the DVD-R 31 for recording the record information data is detected and recorded.
[0033]
As shown in FIG. 3, the information recording apparatus S includes a pickup 1, a spindle motor 2, a spindle driver 3, a laser drive circuit 4, a power control circuit 5, an encoder 6, a regenerative amplifier 8, and a decoder 9. A processor (CPU) 10, a reference clock generator 11 for generating a reference clock signal for rotation control, a BPF (Band Pass Filter) 12, a pre-pit signal detector 13 as pre-pit detecting means, and a pre-pit signal A decoder 14, a wobble signal extractor 15 and a phase comparator 16 as wobble signal extracting means, a phase comparator 17 for generating a rotation control signal, a phase comparator 181, an LPF (Low Pass Filter) 182, a VCO (Voltage) A PLL (Phase Locked Loop) circuit 18 including a Controlled Oscillator 183 and a phase shifter 19 are included.
[0034]
Among these, the BPF 12, the pre-pit signal detector 13, the wobble signal extractor 15, and the phase comparator 16 constitute the phase comparison device PD in the present invention. Further, a PLL circuit 18 and a phase shifter 19 are added to constitute a recording clock signal generator G. In addition, information data to be recorded (not shown) is input to the information recording apparatus via an interface 7 from an external host computer.
[0035]
Next, the overall operation will be described.
The pickup 1 includes a laser diode, a polarization beam splitter, an objective lens, a photodetector, and the like (not shown), and performs a recording operation according to a laser driving signal based on recording information data supplied from the laser driving circuit 4. The recording information data is recorded by irradiating the information recording surface of the DVD-R 31 with the changing output power, and at the time of the reading operation, the light beam B is applied to the DVD- with a constant output power (reading power). It irradiates R31 and operates so that the reflected light is received by the photodetector.
[0036]
Further, the pickup 1 receives reflected light from the information recording surface of the light beam irradiated on the information recording surface by a photodetector, converts it into an electric signal, and performs arithmetic processing based on, for example, a radial push-pull method. As a result, the wobble signal of the pre-pit 34 and the groove track 32 and the detection signal SDT carrying the recorded information data are generated and output to the reproduction amplifier 8.
[0037]
The reproduction amplifier 8 amplifies the detection signal SDT carrying the prepit signal of the prepit 34 and the wobble signal of the groove track 32 output from the pickup 1, and pre-information signal Spp including the prepit signal of the prepit 34 and the wobble signal of the groove track 32. Is output to the BPF 12 in the recording clock signal generator G, and the amplified signal Sp corresponding to the already recorded recording information data is output to the decoder 9 during the reading operation.
[0038]
The decoder 9 performs 8/16 demodulation and deinterleaving on the input amplified signal Sp to decode the amplified signal Sp to generate a demodulated signal SDM, and outputs the demodulated signal SDM to the CPU 10.
[0039]
On the other hand, the BPF 12 removes a noise component included in the pre-information signal Spp supplied from the regenerative amplifier 8 and combines the pre-pit signal at a predetermined position (for example, maximum amplitude position) of the wobble signal (FIG. 5 ( a)) is output to the pre-pit signal detector 13 and the wobble signal extractor 15.
[0040]
The prepit signal detector 13 which is a prepit signal detecting means comprises a comparator (not shown) for comparing the composite signal Spc with a predetermined reference value, for example, a level Vrp larger than the maximum amplitude value of the wobble signal in FIG. During the period when the amplitude level of the composite signal Spc is larger than the reference value Vrp, that is, the period when the prepit exists, the prepit detection signal SPD which is a pulse signal is output to the prepit signal decoder 14 and the phase comparator 16.
[0041]
The pre-pit signal decoder 14 decodes pre-information including address information on the DVD-R 31 from the supplied pre-pit detection signal SPD and outputs it to the CPU 10.
[0042]
On the other hand, the wobble signal extractor 15 which is a wobble signal extracting means compares the composite signal Spc with a predetermined reference value, for example, the intermediate level Vr0 of the PP (Peak to Peak) value of the wobble signal in FIG. A comparator including a pulse signal (FIG. 5B) in which the amplitude level of the composite signal Spc is H (High) during a period in which the amplitude level of the composite signal Spc is greater than the reference value Vr0, as the extracted wobble signal SWB; 17 and the PLL circuit 18 which is a recording clock signal generating means.
[0043]
The PLL circuit 18 includes a phase comparator 181, an LPF 182, a VCO 183 and a frequency divider 184, and outputs a clock signal SCK synchronized with the phase of the input extracted wobble signal SWB to the phase shifter 19.
[0044]
On the other hand, the phase comparator 16 performs a phase comparison between the prepit detection signal SPD and the extracted wobble signal SWB by the action described later, and a deviation from a predetermined phase relationship between the prepit detection signal SPD and the extracted wobble signal SWB, that is, The phase adjustment signal SCNT indicating the amount of fluctuation with respect to the phase that the extracted wobble signal SWB should originally have is output to the phase shifter 19.
[0045]
The phase shifter 19 adjusts the phase of the clock signal SCK supplied from the PLL circuit 18 based on the phase adjustment signal SCNT and outputs it to the encoder 6 and the power control circuit 5 as a recording clock signal SCR by a method described later. To do.
[0046]
On the other hand, the phase comparator 17 compares the phase of the input extracted wobble signal SWB with the reference clock signal SREF carrying the reference frequency component of the rotational speed of the DVD-R 31 supplied from the reference clock generator 11, and the difference The signal is supplied to the spindle motor 2 via the spindle driver 3 as a rotation control signal. As a result, a spindle servo is constructed, and the DVD-R 31 is rotated at a predetermined rotational speed.
[0047]
On the other hand, under the control of the CPU 10, the interface 7 performs an interface operation for taking in the recording information data SRR transmitted from the host computer (not shown) into the information recording apparatus, and the recording information data is transmitted to the encoder 6. Send to.
[0048]
The encoder 6 performs ECC processing, 8/16 modulation processing and scrambling processing using the recording clock signal SCR supplied from the phase shifter 19 as a timing signal, generates a modulation signal SRE, and outputs the modulation signal SRE to the power control circuit 5. .
[0049]
The power control circuit 5 converts the waveform of the modulation signal SRE (so-called write signal) based on the recording clock signal SCR output from the clock signal generator G in order to improve the shape of the recording pits formed on the disk. (Strategy processing) and output to the laser drive circuit 4 as a recording signal SD.
[0050]
The laser drive circuit 4 actually drives a laser diode (not shown) in the pickup 1 and outputs a laser drive signal for emitting the light beam B with the emission power corresponding to the supplied recording signal SD.
[0051]
In the recording operation, the CPU 10 obtains address information from the pre-information supplied from the pre-pit signal decoder 14, and records information data at a position on the DVD-R 31 corresponding to the address information. Control the whole. In the reproduction operation, the CPU 10 acquires the record information data recorded on the disc 31 from the demodulated signal SDM and controls the entire information recording apparatus so as to output the record information data to an external host computer. .
[0052]
Next, more specific configurations of the phase comparator 16 and the phase shifter 19 according to the present invention will be described with reference to FIGS.
[0053]
The phase comparator 16 includes a triangular wave generating circuit 163 as a periodic signal generating means for generating a triangular wave signal having a predetermined inclination angle during the H level of the extracted wobble signal SWB, and the generated timing signal at the detection timing of the prepit detection signal SPD. And a sample hold circuit 164 as a holding means for holding the amplitude level of the triangular wave signal.
[0054]
The triangular wave generating circuit 163 includes a capacitor 45 whose one end is grounded, a constant current source 46 which is connected to the other end of the capacitor 45 and supplies a constant current to the capacitor 45, one end is grounded and the other end is connected to the other end. The switch 47 is connected to a connection point a between the capacitor 45 and the constant current source 46. The switch 47 is opened in accordance with the extracted wobble signal SWB supplied via the buffer 161 while the extracted wobble signal SWB is at the H level, and the extracted wobble signal SWB is at the L (Low) level. This period is closed.
[0055]
With the above configuration, a triangular wave signal is generated. That is, when the extracted wobble signal SWB becomes H level and the switch 47 is opened, a constant charging current supplied from the constant current source 46 to the capacitor 45 causes an inclination angle corresponding to the capacitance of the capacitor 45. The terminal voltage at the connection point a, that is, the charging voltage of the capacitor 45 rises (T1 in FIG. 5D).
[0056]
On the other hand, when the extracted wobble signal SWB becomes L level and the switch 47 is closed, the charging voltage of the capacitor 45 is discharged at once through the switch 47, and the connection point a becomes the ground voltage (FIG. 5D). T2). During this time, the charging current supplied from the constant current source 46 is also bypassed by the capacitor 45 through the switch 47. When the switch 47 is opened again, the supply of the charging current to the capacitor 45 is resumed, and the terminal voltage of the capacitor 45 rises from the ground voltage with a certain slope with time (T3 in FIG. 5D). ). In this way, the triangular wave generation circuit 163 generates a triangular wave signal whose amplitude level changes at a constant rate during the H level period of the extracted wobble signal SWB, and outputs the triangular wave signal to the sample hold circuit 164 via the buffer 162. To do.
[0057]
The sample hold circuit 164 includes a switch 48 that relays the triangular wave signal supplied via the buffer 162 to the capacitor 49 according to the pre-pit detection signal SPD, and a capacitor 49 that holds the voltage level of the relayed triangular wave signal. The
[0058]
The switch 48 is closed when the pre-pit detection signal SPD is at the H level and supplies a triangular wave signal to the capacitor 49, and is open when the pre-pit detection signal SPD is at the L level and is supplied to the capacitor 49 of the triangular wave signal. The supply of
[0059]
Therefore, capacitor 49 holds the charging voltage according to the amplitude level of the triangular wave signal supplied during the H level period of prepit detection signal SPD until the next H level period of prepit detection signal SPD arrives. Become. The charging voltage held by the capacitor 49 is supplied to the phase shifter 19 via the buffer 165 as the phase adjustment signal SCNT.
[0060]
As described above, the phase comparator 16 generates a triangular wave signal having a predetermined inclination angle by charging and discharging the capacitor 45 according to the transition state between the H level / L level of the extracted wobble signal SWB, and the triangular wave The amplitude level of the signal is sampled / held at the detection timing of the pre-pit detection signal SPD.
[0061]
The groove that carries the wobble signal and the prepit that carries the prepit signal in the DVD-R 31 are recorded with a predetermined phase relationship as shown in FIG. Therefore, if the phase of the extracted wobble signal SWB output from the wobble signal extractor 15 and the prepit detection signal SPD output from the prepit signal detector 13 is in the predetermined phase relationship, the sampled / held signal level is The voltage level is always a predetermined voltage level (for example, the intermediate amplitude level VM of the triangular wave signal in FIG. 5D).
[0062]
However, if there is a wobble signal component leaking from an adjacent groove track due to the influence of crosstalk, the extracted wobble signal SWB from the groove track may vary on the time axis due to interference with the wobble signal component. Will occur. On the other hand, as described above, since the pre-pit signal is not formed close to the radial direction of the DVD-R 31, it is not affected by crosstalk from the adjacent land track, and is thus detected from the composite signal SPC. The pre-pit detection signal SPD can be regarded as an accurate timing signal without fluctuation on the time axis based on crosstalk.
[0063]
Therefore, by sampling / holding the triangular wave signal generated from the extracted wobble signal SWB by the pre-pit detection signal SPD, the deviation amount from the predetermined phase relationship, that is, the fluctuation amount from the original phase of the wobble signal is known. Is possible. That is, the phase comparator 16 is centered on the intermediate amplitude level VM in this example according to the phase difference between the extracted wobble signal SWB and the prepit detection signal SPD (time axis error of the extracted wobble signal caused by crosstalk). The amplitude level) is output. Such a phase difference signal is supplied to the phase shifter 19 as the phase adjustment signal SCNT.
[0064]
On the other hand, the phase shifter 19 includes a transistor 191 to which the clock signal SCK output from the PLL circuit 18 is supplied to the base terminal B via the capacitor 195, and an anode connected to the collector terminal C of the transistor 191 and a cathode. Is connected to the resistor 193 via the capacitor 196 at the connection point b, and one resistor is connected to the emitter terminal E of the transistor 191 and the other end is connected to the connection point b. 193.
[0065]
The phase adjustment signal SCNT supplied from the phase comparator 16 is connected to the cathode of the variable capacitance diode 192 through the resistor 194. The recording clock signal SCR is output from the connection point b via the buffer 198. The plurality of resistors 197 are bias resistors of the transistor 191.
[0066]
With the above configuration, the clock signal SCK supplied from the PLL circuit 18 is input to the phase shifter 19, and the phase of the clock signal SCK is phase-shifted according to the phase adjustment signal SCNT supplied from the sample hold circuit 164. The That is, the clock signal SCK supplied to the base terminal B of the transistor 191 is output from the collector terminal C as an inverted signal whose phase is inverted by 180 degrees with respect to the input clock signal SCK, and from the emitter terminal E, the input clock signal. Is output as an in-phase signal. At this time, if the reactance value based on the capacitances of the variable capacitance diode 192 and the capacitor 196 is sufficiently smaller than the resistance value of the resistor 193, the output signal from the connection point b, that is, the record output from the phase shifter 19 is used. The clock signal SCR for use is shifted approximately 180 degrees with respect to the input clock signal SCK.
[0067]
Conversely, if the reactance value is sufficiently larger than the resistance value, the input clock signal SCK and the recording clock signal SCR remain in phase. As described above, the phase shift amount changes according to the impedances of the variable capacitance diode 192, the capacitor 196, and the resistor 193. When a phase shift amount of 180 degrees or more is required, the phase shifters 19 may be connected in cascade to form a multistage configuration.
[0068]
In this embodiment, the phase difference signal output from the phase comparator 16 is supplied to the variable capacitance diode 192 as the phase adjustment signal SCNT, and the terminal voltage of the variable capacitance diode 192 is changed by the phase adjustment signal SCNT. The reactance value of the diode is changed, and the phase shift amount of the clock signal SCK is changed to obtain the recording clock signal SCR. In other words, the amount of deviation is canceled out depending on how much the signal level of the phase adjustment signal SCNT deviates from the above-mentioned VM indicating that the phase relationship between the extracted wobble signal and the pre-pit detection signal is a predetermined phase relationship. In this direction, the phase shift amount of the clock signal SCK is adjusted, and the adjusted clock signal is output to the encoder 6 and the power control circuit 5 as a recording clock signal.
[0069]
In this way, fluctuations on the time axis of the clock signal generated based on the wobble signal that cannot ignore the influence of crosstalk are corrected using pre-pits that are not affected by crosstalk, so the disk rotation is highly accurate. It becomes possible to generate a clock signal for recording synchronized with.
[0070]
Second embodiment of phase comparator
Next, another embodiment of the phase comparison apparatus will be described with reference to FIGS. FIG. 6 is a block diagram showing a second embodiment of the phase comparison apparatus. In the second embodiment, a phase comparator 26 that realizes the operation of the phase comparator 16 in the first embodiment by digital signal processing is employed. As shown in FIG. 6, the phase comparator 26 includes a triangular wave generation circuit 261, a holding circuit 262, an arithmetic circuit 263, a D / A circuit 264, and a timing generation circuit 265.
[0071]
As shown in FIG. 7, the triangular wave generating circuit 261 is supplied with the extracted wobble signal SWB as a LOAD signal, and counts the clock signal SCK generated by the PLL circuit 18 only when the extracted wobble signal SWB is at a high level, for example. It is composed of a circuit and outputs the counted number of clock signals SCK as nbit (n is an integer of 2 or more) digital values Q1,.
The digital values Q1,..., Qn correspond to the amplitude level of the triangular wave output of the triangular wave generating circuit 163 in the first embodiment.
[0072]
As shown in FIG. 7, the holding circuit 262 is composed of three D-type flip-flops that receive the outputs Q1,..., Qn of the triangular wave generation circuit 261, and each input signal is received by a timing generation circuit 265 described later. Latched (held) at timings indicated by timing 1, timing 2 and timing 3 which are timing signals generated based on the pre-pit detection signal SPD.
[0073]
That is, the holding circuit 262 latches the outputs Q1,..., Qn of the triangular wave generation circuit 261 with signals of timing 1, timing 2, and timing 3 generated from the prepit detection signal SPD, and measures each as a digital value. A value 1, a measured value 2, and a measured value 3 are output.
[0074]
Next, as shown in FIG. 8, the arithmetic circuit 263 includes an adder circuit and a divider circuit that divides by three. That is, the arithmetic circuit 263 adds the measurement value 1, the measurement value 2, and the measurement value 3 output from the holding circuit 262 by the signal of the calculation timing 1 supplied from the timing generation circuit 265, and sets the addition result as the calculation value 1. Further, the operation value DSCNT is an average value of the measurement value 1, the measurement value 2, and the measurement value 3 by dividing the signal by the calculation timing 2 signal supplied from the timing generation circuit 265 by 3. Is output as a digital value.
[0075]
The D / A circuit 264 converts the digitized calculation value DSCNT, which is an average value of the measurement value 1, the measurement value 2, and the measurement value 3, output from the calculation circuit 263, into a phase adjustment signal SCNT as an analog value. Is for.
[0076]
Next, the timing generation circuit 265 will be described with reference to FIG. The timing generation circuit 265 includes a logic circuit having the pre-pit detection signal SPD and the clock signal SCK as input signals. Based on the pre-pit detection signal SPD, the timing generation circuit 265 receives an input signal from the triangular wave generation circuit 261 in the holding circuit 262, that is, monotonically increases. A timing signal 1, a timing signal 2, a timing signal 3 indicating the timing of holding the signal, and an arithmetic timing signal 1 and an arithmetic timing signal 2 indicating the timing at which the arithmetic circuit 263 performs arithmetic operations are output. Also, a conversion timing signal is output to the D / A circuit 264.
[0077]
As shown in FIG. 2, the timing signal 1, the timing signal 2, and the timing signal 3 have timings at which the prepits B2, B1, and B0 should exist in the period of one sync frame (for example, 7T from the start position of the sync frame, Generated by performing a logical operation (logical product) of the gate signal 1, the gate signal 2, and the gate signal 3 and the pre-pit detection signal SPD that are opened (become HI level) including a predetermined range including 193T and 379T timing). The
[0078]
More specifically, as shown in FIG. 9, the timing signal 1 is generated by calculating the logical product of the gate signal 1 and the prepit detection signal SPD that open in a predetermined range including the timing at which the prepit B2 should exist ( At time t1 in FIG. 9, the timing signal 2 is generated by calculating the logical product of the gate signal 2 opened in a predetermined range including the timing at which the prepit B1 should exist and the prepit detection signal SPD (time t2 in FIG. 9). ), The timing signal 3 is generated by calculating the logical product of the gate signal 3 and the prepit detection signal SPD that are opened in a predetermined range including the timing at which the prepit B0 should exist (time t3 in FIG. 9). Therefore, for example, when the prepit detection signal SPD is not generated even at the timing when the prepits B2, B1, B0 and the prepit B1 should exist as shown at time t4, t5, t6 and time t8 in FIG. If the prepit is not actually recorded or if it is recorded but not detected by the prepit detector 13, the timing signals 1, 2, 3 and the timing signal 2 are not generated.
[0079]
The calculation timing signal 1 indicates the timing for adding and calculating the measurement values latched in response to the timing signal 1, the timing signal 2, and the timing signal 3. As shown in FIG. Occurs at the timing of closing (becomes L level). The operation timing signal 2 indicates the timing for dividing the result of the addition operation by the operation timing signal 1, and is used for the addition operation from the generation timing of the operation timing signal 1 in the operation circuit 263 (FIG. 8). It is generated after the passage of time corresponding to the time required. The operation value DSCNT obtained by the division operation by the operation timing signal 2 is held until the next operation timing signal 2 is generated and a new division operation is executed.
The calculation timing signal 1 and the calculation timing signal 2 also occur when the pre-pit detection signal SPD does not exist at the above-described times t4, t5, and t6. In this case, the measurement value 1, the measurement value 2, and the measurement timing signal 2 Since the previous value 3 is held in the holding circuit 262, the operation value DSCNT is also held after all.
[0080]
Therefore, for example, even when a prepit that is not originally recorded is erroneously detected due to noise or the like at time t12 shown in FIG. 9, the phase is averaged with the measured values based on the prepits detected at times t10 and t11. Since the adjustment signal SCNT is generated, the influence of the erroneous detection at the time t12 does not remain until the next prepit is detected, and the influence of the erroneous prepit detection due to noise or the like on the phase adjustment signal SCNT is reduced. Is possible.
[0081]
As shown in FIG. 3 to FIG. 9 described above, the recording clock signal is phase-adjusted based on the phase adjustment signal obtained by phase comparison between the signal carrying the phase information of the extracted wobble signal and the prepit detection signal. In addition, an effect of generating a recording clock that follows the rotation of the disk with high accuracy can be expected.
[0082]
In the embodiment shown in FIGS. 3 to 9, the example in which the DVD-R in which the prepits are formed between the wobbled groove tracks (land tracks) is used as the recording medium has been described. The present invention can also be applied to a recording medium in which prepits are formed on a certain groove track.
In the above description, the triangular wave generating circuits 163 and 261 have described the example in which the triangular wobble signal is generated in the period when the extracted wobble signal is at the H level, that is, half the period of one cycle of the extracted wobble signal. A triangular wave may be generated over one period of the signal.
[0083]
【The invention's effect】
As described above, in the phase comparison device of the present invention, the groove track as the information recording track wobbled by the wobble signal having a predetermined frequency, and the land track as the guide track for guiding the recording beam to the information recording track And a pre-pit that is formed on the land track with a predetermined phase relationship with the wobble signal and not formed on the adjacent land track on the same straight line in the disk radial direction. The phase of the extracted wobble signal and the pre-pit detection signal for detecting the pre-pit are compared in the detection of the rotational phase of the disc when information is recorded on the optical disc, so that the desired groove is obtained by crosstalk using the wobble signal of the adjacent groove track. On track Even when the time axis of the extracted wobble signal changes, it is possible to accurately detect the fluctuation amount of the extracted wobble signal with respect to the original phase, and as a result, a recording clock signal that is accurately synchronized with the rotation of the disc is generated. can do.
[0084]
  In particular,Even if the prepit signal is erroneously detected due to the influence of noise, etc., since the phase adjustment signal is generated by comparing the phase of the extracted wobble signal extracted from the groove track and the prepit detection signal, the prepit is used. It is possible to reduce the influence of signal misdetection and provide a highly accurate phase comparison device.
[Brief description of the drawings]
FIG. 1 is a relationship diagram illustrating an example of a configuration of a wobbling groove and a prepit.
FIG. 2 is a diagram showing an example of a recording format in the DVD-R 31 of the embodiment.
FIG. 3 is a block diagram showing an overall configuration of an information recording apparatus including a phase comparison apparatus according to the first embodiment of the present invention.
FIG. 4 is a diagram illustrating a specific configuration example of a phase comparator 16 and a phase shifter 19 that generates a recording clock signal SCR in the phase comparison device according to the first embodiment of the present invention;
5 is a schematic waveform diagram illustrating the operation of the circuit of FIG.
FIG. 6 is a block diagram of a phase comparator in a phase comparison device according to a second embodiment of the present invention.
7 is a diagram showing a specific configuration example of a triangular wave generation circuit 261 and a holding circuit 262 that constitute the phase comparator 26. FIG.
8 is a diagram showing a specific configuration example of an arithmetic circuit 263 that constitutes the phase comparator 26. FIG.
FIG. 9 is a timing chart for explaining the operation of the block diagram of FIG. 6;
[Explanation of symbols]
1 ・ ・ ・ ・ Pickup
2 ... Spindle motor
3 ... Spindle driver
4 ··· Laser drive circuit
5 ··· Power control circuit
6 ・ ・ ・ ・ Encoder
7 ··· Interface
8 ・ ・ ・ ・ Regenerative amplifier
9 ・ ・ ・ ・ Decoder
10 ··· Processor
11 ··· Reference clock generator
12 ··· BPF
13... Prepit signal detector as prepit detection means
14... Prepit signal decoder
15... Wobble signal extractor as means for extracting wobble signal
16, 26... Phase comparator
17... Phase comparator
18... PLL circuit
19 ・ ・ ・ ・ Phase shifter
163, 261... Triangular wave generating circuit as periodic signal generating means
164... Sample hold circuit as holding means
31 ・ ・ ・ ・ DVD-R
262... Holding circuit as holding means
263... Arithmetic circuit as averaging means
H.264 D ... A circuit
265... Timing generation circuit

Claims (2)

An information recording track wobbled by a wobble signal having a predetermined frequency; a guide track for guiding a recording beam to the information recording track; and a predetermined phase with respect to the wobble signal on the guide track. a phase comparator for comparing the phase of the wobble signal in the information recording apparatus for recording information on an optical disk having a formed with a relation Help Lippit and said pre-pit,
Wobble signal extraction means for extracting the wobble signal;
Prepit detecting means for detecting the prepit;
A periodic signal generating means for generating a periodic signal that is synchronized with the extracted wobble signal and monotonously changes for a period corresponding to the predetermined frequency;
Holding means for latching the amplitude level of the periodic signal at the detection timing of the prepit;
Averaging means for averaging the latched amplitude levels;
A phase comparison apparatus comprising: The phase comparison apparatus according to claim 1, wherein the holding unit holds a plurality of the amplitude levels latched at the detection timing of the prepit.

Images