JP4384995B2 - Optical information recording apparatus and method, and signal processing circuit - Google Patents

Description

  The present invention relates to an optical information recording apparatus and method, and a signal processing circuit, and more particularly, to an optical information recording apparatus and method and a signal processing circuit that are effective for detecting a length deviation amount of a signal that easily causes interference.

  Information recording on an optical information recording medium such as an optical disk is performed by modulating recording data by an EFM (Eight to Fourteen Modulation) method or an 8-16 modulation method, and forming a recording pulse based on the modulation signal. Based on this, the intensity of the laser beam and the irradiation timing are controlled, and recording pits are formed on the optical disk.

  Here, since the recording pits are formed using heat generated by laser light irradiation, the recording pulse needs to be set in consideration of the heat storage effect, thermal interference, and the like. Therefore, conventionally, a plurality of parameter settings constituting a recording pulse are defined in the form of a strategy for each type of optical disc, and the optimum one for the recording environment is selected from these strategies to perform recording on the optical disc. It was.

  This strategy is optimal because it depends not only on individual differences in optical information recording devices such as pickup spot diameter variation and mechanism accuracy variation, but also on the manufacturer type and recording speed of the optical disc used for recording and reproduction. Setting the strategy improves the recording quality.

  For this reason, the optimum strategy of the optical disc corresponding to each manufacturer type is obtained and stored in the memory in advance corresponding to each manufacturer type. When recording information on the optical disc, the manufacturer type of the optical disc recorded on the optical disc is recorded. A method is proposed in which an optimum strategy corresponding to the read manufacturer type is read from the memory and used.

  However, according to the above method, optimum recording can be performed on a manufacturer-type optical disc stored in the memory in advance, but optimum recording can be performed on a manufacturer-type optical disc not stored in the memory. Moreover, even in the case of a manufacturer-type optical disk stored in advance in the memory, if the recording speed is different, optimum recording cannot be performed in this case.

Therefore, as shown in the following Patent Documents 1 to 4, many methods have been proposed in which test recording is performed in advance for each recording condition, and an optimum strategy is determined based on the test recording so as to be compatible with various optical disks. ing.
JP-A-5-144001 JP-A-4-137224 JP-A-5-143999 However, in the methods disclosed in Japanese Patent Laid-Open No. 7-233506, since it is necessary to perform test recording before starting information recording, the strategy cannot be corrected simultaneously with recording. It is difficult to cope with cases where the optimum conditions of the inner and outer circumferences are different.

This problem, that is, the optical disc has slightly different recording characteristics from the inner peripheral part to the outer peripheral part, and the recording speed may be different between the inner peripheral part and the outer peripheral part on the recording apparatus side, so that there is a problem that an internal / external difference occurs in recording quality. As a technique for solving the problem, a technique for reducing the internal / external difference by adjusting the laser output is disclosed in the following patent document.
JP-A-53-050707 discloses a technique for automatically optimizing a laser output by detecting a change in the amount of light of an auxiliary beam, and this kind of technique is referred to as OPC. Is done.

  Since the OPC as described above is a technique for adjusting power, a correction condition can be obtained by a statistical index such as an asymmetry value, and thus real-time correction in which correction is performed while recording is possible. When correcting the phase condition of the pulse, it is difficult to cope with conventional OPC because it is necessary to detect the amount of deviation between the recording pulse and the pit formed on the optical disk.

Therefore, in order to perform real-time correction of pulse conditions, a technique for detecting the positions and lengths of pits and spaces simultaneously with recording is necessary. As one approach to this, a technique for reproducing almost the same location as the recording location is disclosed in Patent Document 6 below.
However, this method can be applied to magneto-optical recording, but is difficult to apply to optical recording that does not use magnetism. That is, in magneto-optical recording, information is recorded by magnetic modulation, so the laser output is unmodulated. In optical recording, information is recorded by laser output modulation. Is a problem that extends to the playback side.

As a technique for solving this problem, a technique shown in the following document is known.
JP-A-1-287825 Japanese Patent Laid-Open No. 7-129956 Japanese Patent Laid-Open No. 2004-22044 Japanese Patent Laid-Open No. 9-147361 discloses a technique for extracting a reproduction signal by irradiating a separate beam to an unrecorded area and a recorded area and dividing the obtained separate signals. For example, it is possible to correct the collapse of the reproduction signal waveform due to the light intensity modulation of the laser during information recording.

  Patent Document 8 is a technique for obtaining a reproduction signal by canceling the modulated output with a laser output appropriately amplified by an AGC (Auto Gain Control) with a reverse phase clock.

  Further, Patent Document 9 is a technique for canceling the distortion of the reproduction signal accompanying the waveform fluctuation of the recording pulse by creating and canceling out a signal corresponding to the waveform fluctuation of the recording pulse by a delay inversion equivalent circuit.

  These methods disclosed in Patent Documents 7 to 9 are all techniques for canceling a modulation component by calculation, and are theoretically considered to be cancelable. However, there are various methods for practical use in terms of cancellation accuracy and calculation speed. The problem remains.

  Further, Patent Document 10 detects a recording state deviation in real time by using a delayed pulse obtained by delaying a pulse used for recording and a gate signal obtained by inverting the modulated signal and putting it in a phase comparator together with a reproduction pulse. Technology.

  However, in the method disclosed in Patent Document 10, since the pit is reproduced when the recording pulse is OFF, it is difficult to obtain a reproduction signal with sufficient quality when the output of the sub beam is low. . In particular, in a configuration in which a reproduction sub-beam is generated by branching from a recording main beam, it becomes difficult to allocate a sufficient output to the sub-beam when the branching ratio is 20: 1 or 30: 1.

  That is, the branching ratio in Patent Document 10 is 8: 1, but this branching ratio tends to increase as the recording speed increases, and the beam output when the recording pulse is OFF is normally 1 mW or less. For this reason, the intensity of the recording surface reflected light that can be detected when the recording pulse is turned off becomes very small. If the intensity of light that can be detected becomes weak, it becomes more susceptible to circuit noise, media noise, etc., and as a result, a good detection signal cannot be obtained.

  On the other hand, as a method for detecting the lengths of pits and spaces recorded on an optical disc, there are an integral detection method using an integrated value of a reproduction RF signal, and an amplitude detection method using a single differential value of the RF signal. A peak detection method using a twice differential value of an RF signal is known.

  However, in an optical recording apparatus that performs a reproducing operation using a laser beam having a relatively short wavelength, interference between a spot and a pit does not occur in an optical medium recorded with low density. Is difficult to detect.

  Further, in the method using the one-time differential value of the RF signal, when the recording power changes with the change of the recording speed, the binarized signal at the same slice level is the result of detecting pits and spaces having the same length. However, it is detected as a different length. In order to solve this problem, means for changing the slice level in accordance with the recording speed can be considered, but it is difficult to set an appropriate slice level for each recording speed.

Further, as a peak detection method using the twice differential value of the RF signal, for example, a method shown in the following patent document is known.
International Publication WO 96/24130 The method described in this patent document 10 is a so-called tanger difference signal of an optical detector having two regions partitioned by a dividing line optically perpendicular to the rotation direction of the optical media. By differentiating the local push-pull signal, a signal equivalent to a value obtained by differentiating the RF signal twice is generated, and by using this signal, the edge position of the pit can be detected.

  However, if pits and spaces recorded on optical density type optical media, for example, DVD class media, are detected by the technique described in Patent Document 10, short pits and spaces such as 3T and 4T that are likely to cause interference. An error occurs in the differential value of the tangential push-pull signal, and a value different from the original pit and space length is detected.

  On the other hand, in a recording system that requires detection and correction at a higher speed, it is difficult to secure a desired clock frequency due to restrictions on the LSI to be used, and there arises a problem that desired detection accuracy cannot be obtained. .

As a technique for solving this problem, for example, as shown in the following patent document, an example in which resolution is improved by shifting a plurality of clocks is known.
However, in recent high-density and high-speed recording systems, resolution is insufficient even with this method, and a more accurate detection method is required.

  SUMMARY OF THE INVENTION The present invention provides an effective technique for detecting the length deviation of a signal that is likely to cause interference, and an object of the present invention is to apply this technique to real-time correction in which correction is performed simultaneously with recording.

  In order to achieve the above object, according to the first aspect of the present invention, there is provided an optical information recording in which pits and spaces are formed in an optical recording medium by irradiating a laser beam based on a recording pulse including a plurality of types of code information. In the apparatus, means for reproducing pits and spaces recorded on the medium, means for generating a signal including only a predetermined code from the signal obtained by the reproduction, and integrating a signal amount including only the predetermined code And a means for performing the above.

  Thus, by extracting the signals related to a specific code and accumulating the signals, the accumulated amount of reproduction information related to the same type of code can be obtained. Therefore, if the desired number of times of accumulation is repeated, a high-density / high-speed recording system can be obtained. Can also obtain the desired detection resolution. For the comparison of the accumulated amount, for example, a technique based on a voltage obtained by accumulating a reference 6T pulse 100 times can be applied, and preferably, the accumulated value is averaged to average per one pulse. The average amount is obtained and this value is used as a reference.

  Here, the plural types of code information correspond to 3T to 11T in the case of a CD system, 3T to 11T and 14T in the case of a DVD system, and 2T to 8T in the case of a Blu-ray system, In the case of an HD-DVD system, 2T to 11T are applicable.

  The invention according to claim 2 is the invention according to claim 1, further comprising means for averaging the integration results.

  According to a third aspect of the present invention, there is provided an optical information recording apparatus for forming pits and spaces in an optical recording medium by irradiating a laser beam based on a recording pulse including a plurality of types of code information. Means for reproducing pits and spaces recorded in the signal, means for generating a pulse signal including only a predetermined code binarized from the signal obtained by the reproduction, and charging and / or discharging according to the pulse signal By repeating the above, there are provided means for converting the pulse signal into a voltage value, and means for dividing the voltage value by the number of pulses included in the pulse signal.

  In this way, by extracting a pulse related to a specific code, charging and discharging based on this pulse, and dividing the voltage value obtained as a result by the number of pulses, an average value of pulse lengths for the same type of code is obtained. Therefore, if the integration is repeated a desired number of times, the desired detection resolution can be obtained even in a high-density / high-speed recording system.

  According to a fourth aspect of the present invention, there is provided an optical information recording apparatus for forming pits and spaces in an optical recording medium by irradiating a laser beam based on a recording pulse including a plurality of types of code information. Means for reproducing the pits and spaces recorded in the signal, means for generating a pulse signal including only a predetermined code binarized from the signal obtained by the reproduction, and a pulse length corresponding to the predetermined code Means for generating a hollow pulse arranged at the center of the predetermined code, and means for generating an edge pulse obtained by extracting an edge portion of the pulse signal using the hollow pulse. It is characterized by.

  In this way, by performing edge extraction using a hollow pulse, it is possible to cut out a signal in the vicinity of a pulse edge that includes a large amount of deviation elements, so that the deviation amount detection capability can be improved.

  According to a fifth aspect of the present invention, there is provided an optical information recording apparatus for forming pits and spaces in an optical recording medium by irradiating a laser beam based on a recording pulse including a plurality of types of code information. Means for reproducing pits and spaces recorded in the signal, means for generating a pulse signal including only a predetermined code binarized from the signal obtained by the reproduction, and extracting an edge portion of the pulse signal Means for generating an edge pulse, means for converting the edge pulse into a voltage value by repeating charging and / or discharging according to the edge pulse, and dividing the voltage value by the number of pulses included in the pulse signal Means.

  In this way, by performing edge extraction using a hollow pulse, and charging / discharging using this extracted edge information, signals near the pulse edge containing many deviation elements are integrated in an analog manner, It is possible to improve both the detection ability and the resolution of the deviation amount.

  According to a sixth aspect of the present invention, there is provided an optical information recording apparatus for forming pits and spaces in an optical recording medium by irradiating a laser beam based on a recording pulse including a plurality of types of code information. Means for reproducing pits and spaces recorded in the signal, means for generating a signal including only a predetermined code from the signal obtained by the reproduction, means for integrating a signal amount including only the predetermined code, and And means for detecting the length of pits and / or spaces formed on the medium by using the result of integration.

  In this way, by extracting the signals related to a specific code and accumulating the signals, it is possible to obtain the average value of the length amount for the same type of code. Even a system can achieve a desired detection resolution.

  According to a seventh aspect of the present invention, there is provided an optical information recording apparatus for forming pits and spaces in an optical recording medium by irradiating a laser beam based on a recording pulse including a plurality of types of code information. Means for reproducing pits and spaces recorded in the signal, means for generating a pulse signal including only a predetermined code binarized from the signal obtained by the reproduction, and extracting an edge portion of the pulse signal Means for generating an edge pulse, means for converting the edge pulse into a voltage value by repeating charging and / or discharging according to the edge pulse, and dividing the voltage value by the number of pulses included in the pulse signal And a means for detecting a length deviation amount of pits and / or spaces formed on the medium.

  In this way, by performing edge extraction using a hollow pulse, and charging / discharging using this extracted edge information, signals near the pulse edge containing many deviation elements are integrated in an analog manner, It is possible to improve both the detection ability and the resolution of the deviation amount.

  The invention according to claim 8 is the invention according to claim 7, further comprising means for amplifying the edge pulse, and performing voltage conversion of the edge pulse using the amplified signal. To do.

  In this way, by using the amplified edge signal, the shift amount included in the edge signal is also amplified, so that the detection capability is improved.

  The invention according to claim 9 is an optical information recording method for forming pits and spaces in an optical recording medium by irradiating a laser beam based on a recording pulse including a plurality of types of code information. Reproducing the pits and spaces recorded in the signal, generating a signal including only a predetermined code from the signal obtained by the reproduction, integrating a signal amount including only the predetermined code, And a step of detecting the length of pits and / or spaces formed on the medium by using the integration result.

  The invention according to claim 10 is an optical information recording method for forming pits and spaces in an optical recording medium by irradiating a laser beam based on a recording pulse including a plurality of types of code information. A step of reproducing the pits and spaces recorded in the step, a step of generating a pulse signal including only a predetermined code binarized from the signal obtained by the reproduction, and extracting an edge portion of the pulse signal Generating an edge pulse; repeating charging and / or discharging according to the edge pulse to convert the edge pulse into a voltage value; and dividing the voltage value by the number of pulses included in the pulse signal. And a step of detecting a length deviation amount of pits and / or spaces formed on the medium. And wherein the door.

  According to the eleventh aspect of the present invention, there is provided a signal incorporated in an optical information recording apparatus for forming pits and spaces in an optical recording medium by irradiating a laser beam based on a recording pulse including a plurality of types of code information. In the processing circuit, means for reproducing pits and spaces recorded in the medium, means for generating a signal including only a predetermined code from the signal obtained by the reproduction, and a signal amount including only the predetermined code And means for integrating.

  According to a twelfth aspect of the present invention, there is provided a signal incorporated in an optical information recording apparatus for forming pits and spaces in an optical recording medium by irradiating a laser beam based on a recording pulse including a plurality of types of code information. In the processing circuit, means for reproducing the pits and spaces recorded in the medium, means for generating a pulse signal including only a predetermined code binarized from the signal obtained by the reproduction, and the predetermined Means for generating a hollow pulse that is shorter than the pulse length corresponding to the code and disposed in the center of the predetermined code, and generates an edge pulse that extracts the edge portion of the pulse signal using the hollow pulse Means.

  As described above, according to the present invention, since it is possible to accurately detect a signal length shift that is likely to cause interference, it is possible to perform real-time correction with higher accuracy.

  Hereinafter, an optical information recording apparatus according to the present invention will be described in detail with reference to the accompanying drawings. The present invention is not limited to the embodiments described below, and can be modified as appropriate.

  FIG. 1 is a block diagram showing an internal configuration of a drive according to the present invention. As shown in the figure, the drive 100 uses the laser beam output from the laser diode 110 to record / reproduce information to / from the optical disc 500 and transmit / receive data to / from an external device such as a personal computer 600. Do.

  When recording information on the optical disc 500, the recording data received from the personal computer 600 via the interface circuit 218 is encoded by the EFM encoder / decoder 216, and the encoded recording data is processed by the CPU 212. Then, a strategy that is a recording condition for the optical disc 500 is determined, this strategy is converted into a recording pulse by the pulse generation circuit 300, and this recording pulse is output to the LD driver 124.

  The LD driver 124 drives the laser diode 110 based on the input recording pulse. The laser diode 110 controls the output laser beam in response to the recording pulse, and the controlled laser beam is transmitted to the collimator lens 112, The optical disk 500 that rotates at a constant linear speed or a constant rotational speed is irradiated through the diffraction grating 114, the half mirror 116, and the objective lens 118, whereby the optical disk 500 is composed of pits and space rows corresponding to desired recording data. A recording pattern is recorded.

  On the other hand, when reproducing information recorded on the optical disc 500, the reproduction laser beam is irradiated from the laser diode 110 to the optical disc 10 through the collimator lens 112, the diffraction grating 114, the half mirror 116, and the objective lens 118. .

  At this time, a laser beam having a lower intensity than the laser beam used for recording is used as the reproducing laser beam, and the reflected light from the optical disc 500 by the reproducing laser beam passes through the objective lens 118, the half mirror 116, and the light receiving lens 120. The light is received by the detector 122 and converted into an electrical signal.

  The electrical signal output from the detector 122 corresponds to a recording pattern composed of pits and spaces recorded on the optical disc 500. This electrical signal is binarized by the slicer 210 and further decoded by the EFM encoder / decoder 216. And output as a reproduction signal.

  FIG. 2 is an exploded perspective view showing a structure of a pickup unit incorporated in the drive shown in FIG. As shown in the figure, the diffraction grating provided between the laser diode 110 and the surface of the optical disc 500 is composed of two diffraction gratings 114-1 and 114-2. Different grooves 115-1 and 115-2 are formed, respectively.

  When the laser beam 20 is incident on the diffraction grating configured as described above, the first diffraction grating 115-1 branches into three laser beams, and the second diffraction grating 115-2 branches into three laser beams. Then, the five spots 20A to 20E are irradiated onto the disk surface of the optical disk.

  FIG. 3 is a plan view showing the arrangement of the spots irradiated on the surface of the optical disk. As shown in the figure, the recording main beam 20A, the tracking preceding sub-beam 20B, the tracking trailing sub-beam 20C, the reproducing preceding sub-beam 20D, and the reproducing trailing sub-beam 20E are irradiated onto the surface of the optical disc 500. .

  Here, the recording main beam 20A is irradiated onto the group 502-2 formed on the optical disc 500, and pits 506 are formed in the groove 502-2 by irradiation of this beam spot. The recording main beam 20A is set to have the highest emission intensity in order to enable formation of pits in the heat mode.

  The tracking preceding sub-beam 20B is irradiated onto the land 504-2 adjacent to the groove 502-2 irradiated with the main beam 20A, and the tracking subsequent sub-beam 20C includes the groove 502-2 irradiated with the main beam 20A. The land 504-2 adjacent to the land 504-2 opposite to the land irradiated with the sub beam 20B is irradiated.

  The reproduction preceding sub beam 20D is irradiated on the same groove 502-2 as the groove irradiated with the main beam 20A, and is irradiated at a position preceding the main beam 20A. The reproduction subsequent sub beam 20E is irradiated with the main beam 20A. Is irradiated to a position behind the main beam 20A on the same groove 502-2 as the groove irradiated.

  By arranging each spot in this way, a recording pattern formed by the main beam 20A, that is, a recording pattern composed of a combination of the pits 506 and the spaces 508 can be detected by the reproduction sub beam 20E for reproduction. Become.

  FIG. 4 is a conceptual diagram showing the relationship between the spot irradiated on the surface of the optical disc and the detector. As shown in the figure, the detector 122 shown in FIG. 1 includes five light receiving portions 122A to 122E, and each of the light receiving portions is irradiated with reflected light 22A to 22E corresponding to the spots 20A to 20E, respectively. And converted into an electrical signal.

  FIG. 5 is a conceptual diagram showing the relationship between the shape of the recording pulse and the stable region. As shown in the figures, the recording pulse output from the LD driver 124 shown in FIG. 1 has various shapes, and each shows a high output area 50 indicating the ON state of the recording pulse and an OFF state. It includes a low output area 52 and a constant output area 54 that is ON and has little modulation.

  More specifically, FIG. 9A shows a recording pulse that has a constant output in the ON state, and FIG. 10B shows a recording pulse having different heights at the head portion and the subsequent portion. (C) shows recording pulses having different heights at the head, middle, and rear end. FIG. (D) shows the output of several times at the succeeding part after the constant output part is formed at the head. This is a changed recording pulse.

  In the present invention, since the reproduction signal is intended to be taken in with the recording pulse turned on, it is desirable to generate a gate signal to be described later corresponding to the high output region 50, but more desirably. And generated in correspondence with the constant output region 54 which is not easily affected by the modulation. For convenience, the constant output region 54 is defined as a long interval in the most stable state in the high output region 50. However, the constant output region 54 is used as a constant output region even in a stable region shorter than the interval in which the stable state is the longest. It is possible. In the following description, a pulse shape called a castle type in FIG. 5C will be described as an example, but the present invention can also be applied to other recording pulses.

  For example, when it is applied to the recording power used in the phase change type optical disc as shown in the figure, the phase change material is rapidly cooled by the repetition of the high output and the low output to be in an amorphous (non-crystalline) state. A recording pulse composed of an output region 50, a low output region 52 that outputs a power of about 0.7 to 1 mW, which is servoed by the main beam, and a constant output region 54 that is slowly cooled to be in a crystalline state. Of these, a gate signal may be generated in correspondence with the constant output area 54 corresponding to the erasing power, and the signal reproduced by the sub-beam may be taken into the constant output area 54.

  FIG. 6 is a circuit block diagram showing an internal configuration of the pulse generation circuit shown in FIG. As shown in the figure, in this pulse generation circuit 300, the strategy conditions SD1 and SD2 sent from the CPU 212 in FIG. 1 are received by the pulse unit generation circuits 310-1 and 310-2, respectively, and synchronized with the clock signal CLK. Pulse signals PW1 and PW2 are generated.

  Here, the strategy conditions SD1 and SD2 are defined as numerical data indicating the length of the ON period and OFF period of the pulse by the number of clocks, and the pulse unit generation circuits 310-1 and 310- that receive these data. 2 generates a pulse signal having the conditions indicated by the strategy conditions SD1 and SD2 using the clock signal CLK generated in the drive.

  These pulse signals PW1 and PW2 are output to the LD driver 124 of FIG. 1, and the AND operation unit 316 takes the logical product of the inverted signal of the pulse signal PW1 and the pulse signal PW2 to obtain the gate signal Gate as shown in FIG. Is output to the mask circuit 400. The inverted signal of the pulse signal PW1 is generated by the inverting circuit 314.

  FIG. 7 is a timing chart showing the generation concept of the gate signal shown in FIG. As shown in the figures, the gate signal corresponding to the constant output region of the recording pulse is generated using pulse signals PW1 and PW2 which are constituent elements of the recording pulse. That is, as shown in FIGS. 2B and 2C, the pulse signals PW1 and PW2 are generated in synchronization with the clock signal CLK of FIG. 1A, and from this pulse signal PW1, The inversion signal shown in FIG.

  Then, when the levels of the pulse signal PW2 in FIG. 8C and the inverted signal shown in FIG. 4D are defined as shown in the respective figures and the logical product is taken, the gate signal shown in FIG. Is obtained. As a result, the gate signal obtained in this way corresponds to the constant output region of the recording pulse.

  FIG. 8 is a circuit diagram showing an internal configuration of the LD driver shown in FIG. As shown in the figure, the LD driver 124 includes a voltage dividing circuit using resistors R1 and R2 and a synthesizer 126 that synthesizes these output voltages, and the pulse signals PW1 and PW2 from the pulse generation circuit 300 are formed. Is amplified to a predetermined output level via resistors R1 and R2, and then ORed by a synthesizer 126 to generate a recording pulse PWR, which is output to the laser diode 110 in FIG.

  FIG. 9 is a circuit block diagram showing an internal configuration of the mask circuit shown in FIG. As shown in the figure, the mask circuit 400 includes two AND arithmetic units 410-1 and 410-2, and the first stage AND arithmetic unit 410-1 is generated by the pulse generation circuit 300 of FIG. The gate signal Gate and the flag signal Flag generated by the CPU 212 of FIG. 1 are input, and a gate signal Gate ′ obtained by ANDing these is output to the AND calculator 410-2 at the subsequent stage.

  Using this gate signal Gate ′, the AND operator 410-2 masks the RF signal RF-Sub reproduced by the reproduction sub beam 20E for reproduction output from the detector 122E of FIG. The corresponding portion of the RF signal RF-Sub 'is extracted and output to the slicer 210 of FIG. As a result, the RF signal RF-Sub 'reproduced in the constant output region of the recording pulse is selectively extracted, so that highly accurate pit detection is performed.

  Then, based on the detected pit length and phase information, the CPU 212 in FIG. 1 calculates a strategy correction condition, and corrects the strategy condition output to the pulse generation circuit 300. As a result, real-time correction is performed in which recording conditions are corrected during data recording.

  FIG. 10 is a timing chart showing the relationship among the recording pulse, the gate pulse, and the reproduction signal. As shown in FIG. 5A, the recording pulse PWR is a pulse pattern that changes ON / OFF corresponding to a predetermined data pattern. Here, assuming that the constant output region 54 of the pit 14T having the longest unmodulated region is used as a gate signal, the gate signal Gate generated by the pulse circuit 300 of FIG. 1 is shown in FIG. The flag signal Flag output at the timing and generated by the CPU 212 in FIG. 1 is output at the timing shown in FIG. 9C, and the gate signal Gate ′ generated in the mask circuit 400 in FIG. A result obtained by extracting the RF-Sub signal in FIG. 5E using the gate signal Gate ′ is the RF-Sub ′ signal in FIG.

  Thus, since the finally extracted reproduction signal RF-Sub ′ is a signal reproduced in the constant output area 54 of the recording pulse PWR, it is possible to detect pits with high accuracy by using this signal. As a result, the strategy can be accurately corrected.

  FIG. 11 is a conceptual diagram showing a flag signal generation method executed by the CPU shown in FIG. The example shown in the figure is an example in the case where a space 4T existing in the constant output area of the pit 14T is selectively detected. As shown in the figure, the CPU 212 sequentially stores a numerical value corresponding to the data length of the recording pulse in the memory 214, and a space 4T (same as the same in the constant output area of the pit 14T (shown as “P14” in the figure)). In the figure, data having “L4”) is specified, and a flag is set on the data of the specified pit 14T.

  Here, if the time difference between the main beam for recording and the sub beam for reproduction is defined as τ, the CPU 212 converts the time difference τ by the number of clocks, and converts the data length existing between the pit 14T and the space 4T to the time difference τ. Compare with As a result, if the data of the space 4T exists in an area that is separated from the pit 14T by the time difference τ and within the range corresponding to the constant output area of the pit 14T, a flag is set on the pit 14T, The flag signal Flag is output at the timing shown in FIG.

  FIG. 12 is a timing chart showing the relationship between the main beam for recording and the sub beam for reproduction. As shown in FIG. 6A, the output of the recording main beam becomes a high output pulse pattern necessary for pit formation. The pit pattern formed on the optical disk by this pulse irradiation is shown in FIG. As shown.

  On the other hand, as shown in FIG. 5C, the output of the reproduction sub beam is the same timing as the output pattern of the recording main beam, and the output is reduced by the branching ratio compared to the recording main beam. A pit pattern reproduced by this reproduction sub-beam is a pattern delayed by a time difference τ from the pit being recorded, as shown in FIG.

  Therefore, when the space 4T reproduced during the recording of the pits 14T is detected, as shown in FIG. 5E, the pulse space 4T obtained by delaying the recording pulse pattern by the time difference τ, and the recording pulse The position where the constant output area of the pit 14T overlaps may be specified. That is, the first gate signal is generated from the constant output area of the long pit in the recording pulse, and the pulse corresponding to the short pit or space to be detected is selected from the pulse pattern obtained by delaying the recording pulse by the time difference τ. A configuration in which the second gate signal is generated and the RF signal obtained from the reproduction sub-beam is masked using the first and second gate signals is useful.

  FIG. 13 is a timing chart showing the relationship between a recording pulse, a pulse obtained by delaying the recording pulse, and an RF signal. As shown in the figures, a pulse PWR ′ obtained by delaying the recording pulse PWR by the time τ is generated, and a portion where the space 4T of the delayed pulse PWR ′ is included in the constant output region of the pit 14T of the recording pulse PWR. When the gate signal Gate ′ is used, it is possible to selectively detect a short pit or space during recording of a long pit, and as a result, it is possible to accurately detect a pit length shift or a phase shift.

  FIG. 14 is a block diagram showing an example of a technique for detecting a short pit or space during recording of a long pit. This figure shows a configuration example in the case where the EFM encoder / decoder 216 shown in FIG. 1 detects a 4T space existing under the sub-beam while the main beam records a 14T pit.

  In such a configuration, the EFM encoder / decoder 216 temporarily accumulates the 8-bit binarized signal input from the slicer 210 in FIG. 1 in the buffer 250-1 as shown in FIG. The output 8-bit data is converted into 16-bit data according to the conversion table 252 and output to the buffer 250-2. At this time, a delay operation of time T by the delay unit 254 is performed for each conversion.

  The data stored in the buffer 250-2 is output to the counter 256, and is output as data indicating the pulse length nT (n = 3 to 14) to the pulse generation circuit 300 via the CPU 212 shown in FIG. A recording pulse is generated.

  FIG. 15 is a block diagram showing the relationship between the counter 256 shown in FIG. 14 and the pulse generation circuit 300 of FIG. As shown in the figure, the counter 256 includes a 14T decoder 258 for specifying a bit string corresponding to 14T pits from a data stream flowing from the buffer 250-2 toward the pulse generation circuit 300, and a bit string corresponding to 4T space. 4T decoder 259 to specify.

  FIG. 16 is a conceptual diagram illustrating an example when the buffer 250-2 illustrated in FIG. 14 accumulates a bit string. As shown in FIG. 8C, the buffer 250-2 stores data indicating the length of pits or spaces in synchronization with the clock signal shown in FIG.

  For example, the length of 3T is expressed as “100”, the length of 4T is expressed as “1000”, the length of 5T is expressed as “10000”, and the length of 14T is expressed as “10000000000000”. .

  Therefore, when a pulse as shown in FIG. 10B is input, the bit string stored in the buffer 250-2 has a portion corresponding to 4T space “1000” as shown in FIG. The portion corresponding to the 14T pit becomes “10000000000000”, and each pulse width is stored in a format expressed by the number of bits.

  Here, when the interval between the main beam for recording and the sub beam for reproduction is equivalent to 300 bits, as shown in FIG. The position of the 14T pit being recorded is specified, and it is determined whether or not there is a 4T space bit string at a position 300 bits away from the 14T pit.

  As a result, if there is a bit string of 4T space, it is determined that the 4T space can be detected by the sub beam during recording of the 14T pit by the main beam, and the signal obtained at this timing is used in real time. Determine the correction conditions.

  FIG. 17 is a conceptual diagram showing variations of 4T space to be detected during recording of 14T pits. As shown in FIG. 5A, when the recording pulse of 14T pit is composed of a high output 3T pulse, a stable output 9T pulse, and a high output 2T pulse, it falls within the stable output region. The 4T space is a detection target.

  Therefore, it is most desirable to extract the 4T space that appears at the center of the 14T pulse. However, this reduces the probability of appearance, so the case where both ends of the 4T space do not protrude from the stable output region of the 14T pit can be extracted. A counter circuit is provided so that

  For example, the gate signal shown in FIG. 5B is generated from the 14T pit pulse shown in FIG. 6A, and the 4T space indicated by the hatch in FIG. A data pattern that can be specified is prepared, and a bit string that matches the data pattern is extracted.

  FIG. 18 is a block diagram showing another example of a technique for detecting a short pit or space during recording of a long pit. The example shown in the figure is an example of determining whether or not there is a short pit or space during the recording of a long pit, based on the number of pulses generated within a certain time.

  In the circuit block shown in the figure, the binarized signal SL RF-Sub ′ output from the slicer 210 is input to the AND operation unit 422 via the inversion circuit 420-1, and from the pulse generation circuit 300 of FIG. The output gate signal Gate is input to the AND calculator 422.

  The AND operator 422 outputs the logical product of these input signals to the set terminal of the counter 424, and the counter 424 that receives this signal is generated within the interval indicated by the gate signal inverted by the inverting circuit 420-2. The counted number of pulses is counted, and the result is output to the CPU 212 of FIG. 1 as a determination signal Detection Enable. The gate signal inverted by the inverting circuit 420-2 is used as a reset signal for the counter 424.

  The CPU 212 determines whether or not a 4T space exists during recording of 14T pits based on whether the number of pulses indicated by the determination signal is a predetermined number or more, for example, twice or more. The signal obtained from the 4T space is captured.

  FIG. 19 is a timing chart showing a processing example of the circuit block shown in FIG. As shown in FIG. 6A, the signal RF-Sub ′ input to the slicer 210 is binarized at a certain level to generate a pulse signal SL RF-Sub ′ as shown in FIG. Is done.

  Then, the pulse generation circuit 300 shown in FIG. 1 generates the gate signal Gate shown in FIG. 10E generated from the signals shown in FIG. Further, a logical product with the inverted signal shown in FIG. 6F is taken, so that the determination signal Detection Enable shown in FIG.

  FIG. 20 is a conceptual diagram showing the determination criteria of the determination signal generated by the circuit block of FIG. As shown in the figures, in this example, when two or more pulses are counted in the section shown in FIG. 6A, the pulses fall within the gate signal Gate indicating the stable area of 14T during recording of the 14T pit. It is determined that there is a space, for example, a 3T to 7T space, and a signal obtained from this 4T space is captured.

  Therefore, as shown in FIG. 5B, when the pulse can be counted twice in the gate signal, a space that fits in the gate signal Gate indicating the stable area of 14T during recording of the 14T pit, for example, 3T˜ It is determined that there is a 7T space, and a signal obtained from this 4T space is captured. On the other hand, as shown in (c) and (d) of the figure, when the count can be performed only once, it is determined that there is no 4T space during recording of the 14T pit, and no signal is captured.

  FIG. 21 is a block diagram showing another example of a technique for detecting a short pit or space during recording of a long pit. The example shown in the figure is an example of determining whether or not there is a short pit or space during recording of a long pit by measuring the length of a pulse generated in the gate signal.

  In the circuit block shown in the figure, the AND operation unit 422 outputs the binarized signal SL RF-Sub ′ output from the slicer 210, the gate signal Gate output from the pulse generation circuit 300 in FIG. The logical product with CLK is taken and input to the set terminal of the counter 424 as a countable signal Count Pulse, and the counter 424 counts the length of the signal. Note that a reset pulse generated by the reset pulse generation circuit 426 is input to this counter.

  FIG. 22 is a timing chart showing a processing example of the circuit block shown in FIG. As shown in FIG. 6A, the signal RF-Sub ′ input to the slicer 210 is binarized at a certain level to generate a pulse signal SL RF-Sub ′ as shown in FIG. Is done.

  Then, the logical product of the gate signal Gate shown in (c) of FIG. 1 generated by the pulse generation circuit 300 shown in FIG. 1 and the clock signal CLK shown in (d) of FIG. The countable signal Countable Pulse shown in (e) is generated. Note that the clock signal taken up here has been described using an example in which “1T = 1 period”, but the length detection is performed using a faster clock, for example, a clock of “1T = 40 periods”. The resolution may be improved.

  FIG. 23 is a timing chart showing a processing example of the reset pulse generation circuit 426 shown in FIG. As shown in the figure, the reset pulse generation circuit 426 generates the intermediate signal CLK / 2 shown in FIG. 10B by counting the clock signal CLK shown in FIG. The intermediate signal CLK / 2 is counted once every two times to generate the intermediate signal CLK / 4 shown in FIG.

  Then, as shown in FIG. 4D, a reset signal Reset that rises in synchronization with the second rise in FIG. 4C and falls when a length corresponding to the gate signal Gate is scanned is generated. By inputting this reset signal to the reset terminal of the counter 424 shown in FIG. 21, the count result of the counter is reset.

  In addition, in the case where a signal of “1T = 40 cycles” is used as the clock signal shown in FIG. 9A, and the gate signal Gate has a width corresponding to 9T, the same is true when the clock signal is counted 360 times. The reset signal Reset shown in FIG. 4D falls, and the counter 424 is reset.

  Similarly, in the case where a signal of “1T = 2.5 cycles” is used as the clock signal shown in FIG. 5A, and the gate signal Gate has a width corresponding to 9T, the clock signal is turned 22.5 times. When counted, the reset signal Reset shown in FIG. 4D falls, and the counter 424 is reset. However, when the period of the clock signal is not an integral multiple of the unit length T, such as “1T = 2.5 periods”, it is treated as an integral multiple, such as “2T = 5 periods”.

  FIG. 24 is a circuit block diagram showing another configuration example of the mask circuit shown in FIG. The mask circuit shown in the figure is an example when length detection is performed using the tangential push-pull signal Tpp.

  As shown in the figure, the mask circuit 400 includes a tangential push-pull signal generation circuit 430 that generates a tangential push-pull signal Tpp using a signal from a detector 122 having four divided areas, and the tangential push-pull signal generation circuit 430. A VGA circuit 432 (VGA: Volume Gain Amp) for making the amplitude of the push-pull signal Tpp constant, a differentiating circuit 434 for differentiating the tangential push-pull signal Tpp, a differential value of the tangential push-pull signal Tpp, and a gate signal Gate And an AND operation unit 422 that takes the logical product of

  Here, the tangential push-pull signal generation circuit 430 has a rotation direction when the divided areas of the detector 122 are A, B, C, and D in relation to the rotation tangent direction Tan of the optical medium as shown in FIG. The difference between the sum of the signals obtained from A and B located in front of the signal and the sum of the signals obtained from C and D located behind in the rotation direction is obtained, and this difference signal is obtained as the tangential push-pull signal Tpp. Output as. When this relationship is described by an expression, as shown in the figure, “Tpp = (A + B) − (C + D)”.

  The VGA circuit 432 generates a signal Tpp-Sub in which the amplitude of the tangential push-pull signal Tpp is made constant, and the differentiating circuit 434 that receives this signal differentiates the Tpp-Sub signal by Δ (Tpp− Sub) A signal is generated.

  The AND operation unit 422 extracts a signal Δ (Tpp-Sub ′) corresponding to the light output stable region of the recording pulse by taking a logical product of the Δ (Tpp−Sub) signal and the gate signal Gate, and performs a slicer operation. 210 slices the Δ (Tpp-Sub ′) signal at a zero level to generate an SL Δ (Tpp-Sub ′) signal.

  FIG. 25 is a first timing chart showing the operation of the circuit shown in FIG. As shown in FIG. 24A, the RF signal detected by the detector shown in FIG. 24 is a signal of 1 × speed recording indicated by symbol X1.0 and a signal of 1.5 × speed recording indicated by symbol X1.5. Thus, the waveforms are different in amplitude and zero point.

  Also, the tangential push-pull signal Tpp-Sub output from the VGA circuit 432 shown in FIG. 24 is a signal of the 1 × speed recording indicated by the symbol X1.0 and the symbol X1.5 as shown in FIG. The waveform of the 1.5 × speed recording signal shown in FIG. 5 is a waveform in which the zero point coincides although the amplitude is different. The zero point of the tangential push-pull signal Tpp-Sub corresponds to the peak position of the RF signal RF-Sub shown in FIG.

  Further, the differential value Δ (Tpp-Sub) of the tangential push-pull signal output from the differentiating circuit 434 shown in FIG. 24 is the 1 × speed recording indicated by the symbol X1.0 as shown in FIG. The signal and the 1.5 × speed recording signal indicated by the symbol X1.5 have different waveforms, but with a zero point coincident. The zero point of the differential value Δ (Tpp-Sub) of the tangential push-pull signal corresponds to the peak position of the tangential push-pull signal Tpp-Sub shown in FIG. This corresponds to the position where the slope of the RF signal RF-Sub becomes the maximum point.

  FIG. 26 is a second timing chart showing the operation of the circuit shown in FIG. FIG. 11A is a diagram showing a differential value Δ (Tpp−Sub) of the tangential push-pull signal output from the differentiating circuit 434 shown in FIG. 24. This differential value is shown in FIG. Masked with the gate signal Gate, the differential value Δ (Tpp-Sub) of the tangential push-pull signal becomes a signal Δ (Tpp-Sub ′) cut out with the gate signal Gate, as shown in FIG.

  Then, the zero cross point of the signal Δ (Tpp−Sub ′) is extracted by the slice circuit 210 shown in FIG. 24, and a pulse signal SLΔ (Tpp−Sub ′) as shown in FIG. . This pulse signal becomes a short pit or space signal that exists within the high output stable period of the recording pulse described above, and in the above example, becomes a 4T space detection signal.

  By using the differential value of the tangential push-pull signal described above, the length of the pit or space is detected, and the length deviation is detected in real time, and recording is performed while correcting this deviation.

  Here, as described above, simply using the differential value of the tangential push-pull signal causes interference of short signals such as 3T and 4T, and an accurate length cannot be detected.

  Therefore, in the present embodiment, a differential value of the tangential push-pull signal as a correction reference is obtained in advance by test recording in the test area, and recording is performed with a recording laser beam during the main recording in the recording area. The pit or space is reproduced with the reproduction laser beam, the differential value of the tangential push-pull signal is obtained from the obtained reproduction signal, and the difference between the differential value obtained in this recording area and the differential value obtained in the test area is calculated. Considering the amount of length deviation, a recording condition suitable for correcting the amount of deviation is set.

FIG. 27 is a graph showing the relationship between the actual physical length and the length of the pit or space detected using the differential value of the tangential push-pull signal related to the pit and space obtained in the test area. As shown in FIG. 5A, for example, when pits having a length of 3T to 8T are formed in the test area by test recording, a differential value of the tangential push-pull signal with respect to each pit length can be obtained. The length of each pit length can be predicted from the differential value. Here, for the relatively long 5T to 8T pits, a length corresponding to the original physical length indicated by the dotted line in the figure can be obtained, but for the 3T and 4T pits that are likely to cause interference, what is the original physical length? Detected as different lengths.

  Similarly, as shown in FIG. 5B, for example, when a space having a length of 3T to 8T is formed by test recording, a differential value of the tangential push-pull signal with respect to each space length can be obtained. The length of each space length can be predicted from the value. Here, for a relatively long 5T to 8T space, a length corresponding to the original physical length indicated by a dotted line in the figure is obtained, but for a 3T and 4T space where interference is likely to occur, what is the original physical length? Detected as different lengths.

  Therefore, the differential value of the tangential push-pull signal with respect to each pit length shown in FIG. 10A is used as a correction reference, or the differential value of the tangential push-pull signal with respect to each space length shown in FIG. By using the correction reference, the influence of interference can be avoided.

  FIG. 28 is a graph showing the relationship between the differential value of the tangential push-pull signal related to pits and spaces obtained in the recording area and the differential value of the tangential push-pull signal related to pits and spaces obtained in the test area. As shown in FIG. 6A, when a pit pattern having a length of 3T to 8T is recorded in a recording area by a recording laser beam and reproduced by a reproducing laser beam, each of the black circles in the figure is indicated. The differential value of the tangential push-pull signal with respect to the pit length is obtained, and the pits and spaces that conform to the original physical length are obtained by correcting the differential value to the differential value indicated by the white circle in the figure obtained in the test record. The recording pattern consisting of can be formed.

  Similarly, when a space pattern having a length of, for example, 3T to 8T is recorded in the recording area by the recording laser beam and reproduced by the reproducing laser beam, as shown in FIG. The differential value of the tangential push-pull signal for each space shown is obtained, and by correcting this differential value to the differential value indicated by the white circle in the figure obtained in the test record, pits that match the original physical length In addition, a recording pattern including spaces can be formed.

  FIG. 29 is a conceptual diagram showing an example of test recording performed to obtain a differential value of the tangential push-pull signal in the test area. As shown in the figure, the RF lengths a01 to a15 and the tangential for each pit or space length by test recording using a pattern capable of inspecting the pre-phase shift, post-phase shift, and thermal interference of the recording pulse. The differential values b01 to b15 of the push-pull signal are obtained and stored in a predetermined storage area.

  FIG. 30 is a conceptual diagram showing an example of test recording performed to obtain a differential value of the tangential push-pull signal in the recording area. As shown in the figure, each pit or space is extracted from the pit and space pattern formed in the recording area by extracting a pattern capable of inspecting the pre-phase shift, post-phase shift, and thermal interference of the recording pulse. For each length, the differential values c01 to c15 of the tangential push-pull signal and the differences d01 to d15 from the tangential push-pull signal obtained by the test recording shown in FIG. 29 are obtained and stored in a predetermined storage area.

  FIG. 31 is a conceptual diagram showing an example in which the recording pulse is corrected using the difference between the tangential push-pull signals shown in FIG. As shown in the figures, when recording the recording data shown in FIG. 11A on an optical disk, a strategy to which an optimum correction value is applied is set for each pit length. For example, when 3T pits are recorded, as shown in FIG. 5B, the front end correction value Ttop of the front phase shift 3T pit of the stored data shown in FIG. Tlast is read out, and the front end and rear end of the recording pulse are corrected by the Ttop and Tlast.

  When correcting 4T pits or more, as shown in (c) to (f) of the figure, in addition to Ttop and Tlast, the height PWD of the stable area of the corresponding pit length is added to correct the pulse shape. Do.

  FIG. 32 is a circuit block diagram showing another configuration example of the mask circuit shown in FIG. The mask circuit shown in the figure is an example in the case where length detection is performed using a twice differential value of an RF signal.

  As shown in the figure, the mask circuit 400 includes an RF signal generation circuit 436 that generates an RF signal using a signal from a detector 122 having four divided regions, and a VGA that makes the amplitude of the RF signal constant. The circuit 432, differentiating circuits 434-1 and 434-2 for differentiating the RF signal twice, and an AND operation unit 422 for taking a logical product of the twice-differentiated value and the gate signal Gate.

  Here, the RF signal generation circuit 436 outputs the sum of the signals obtained from the divided regions A, B, C, and D of the detector 122 as the RF signal Tpp. When this relationship is described by an expression, as shown in the figure, “RF = (A + B) + (C + D)”.

  The VGA circuit 432 generates a signal RF-Sub in which the amplitude of the RF signal is made constant, and the differentiating circuit 434-1 that receives this signal generates a ΔRF-Sub signal by differentiating the RF-Sub signal. Then, the differentiating circuit 434-2 differentiates the ΔRF-Sub signal to generate a ΔΔRF-Sub signal.

  The AND operation unit 422 extracts a signal ΔΔRF-Sub ′ corresponding to the light output stable region of the recording pulse by taking a logical product of the ΔΔRF-Sub signal and the gate signal Gate, and the slicer 210 makes this ΔΔRF-Sub. 'Slice the signal at zero level to generate the SL ΔΔRF-Sub' signal.

  FIG. 33 is a circuit block diagram showing another embodiment for detecting the lengths of pits and spaces. The example shown in the figure is a technique for performing highly accurate length detection by performing TV conversion on a binarized signal for each code type and accumulating and averaging the obtained voltages. As for the TV conversion, a configuration example is also shown in Japanese Patent Laid-Open No. 05-225568, and the contents described in the document are incorporated in this specification as a reference description.

  In the figure, the code discriminator 320 is a signal composed of only a specific pulse length from the pulse train SL RF-Sub ′ inputted from the slicer 210, for example, a 3T-P signal composed only of 3T pulses, and only 4T pulses. A 5T-P signal composed of only 4T-P signals and 5T pulses is generated.

  The TV converters 322-1 to 322-3 convert the pulse length of each signal generated by the code discriminator 320 into a voltage value, accumulate the voltage value obtained by the conversion for each code, The resultant voltage values 3T-V to 5T-V are output to the average calculation unit 324.

  The average calculation unit 324 calculates the average value of each code length by dividing the voltage value accumulated for each code by the number of received pulses, and obtains length information 3T Length, 4T Length, 5T obtained as a result. The length is output to the CPU 212 shown in FIG. 1, and the reset signal is output to the TV converters 322-1 to 322-3.

  The linear velocity correction unit 326 calculates linear velocity correction amounts Lv3T, Lv4T, and Lv5T for each code according to the recording speed designated by the CPU 212, and outputs these to the TV converters 322-1 to 322-3. .

  FIG. 34 is a timing chart showing the operation of the code discriminator shown in FIG. As shown in FIG. 6A, when a pulse train SL RF-Sub ′ including various codes is input from the slicer 210, the code discriminator 320, as shown in FIGS. Pulse trains 3T-P, 4T-P, and 5T-P, in which only each code length is extracted, are generated.

  FIG. 35 is a circuit diagram showing a configuration of the TV converter shown in FIG. The TV converter 322 shown in the figure is an example of the configuration of the 3T code TV converter 322-1 shown in FIG. 33, but the other codes are similarly configured. The TV converter 322 performs charging and discharging according to the input pulse length, and converts the pulse length into a voltage value by taking the difference between them. Hereinafter, explanation is added for each element.

  The discharge TV conversion circuit 330 includes a constant current source I1, a charging capacitor C1, an offset power source V1, and switches SW1-1 and SW1-2, and receives a reset signal from the average calculation unit 324 shown in FIG. Then, SW1-1 is closed and the capacitor C1 is fully charged.

  Here, when the pulse 3T-P is input from the code discriminator 320 shown in FIG. 33, the switch SW1-2 is closed according to this pulse length, and the charge charged in the capacitor C1 is discharged, and the pulse The output voltage of the capacitor C1 decreases by an amount corresponding to the ON period.

  On the other hand, when the linear velocity correction amount Lv3T is input from the linear velocity correction unit 326 shown in FIG. 33, the offset voltage V1 changes, and the output voltage of the discharge TV conversion circuit 330 changes by this correction amount.

  The chargeable TV conversion circuit 332 includes a constant current source I2, a charging capacitor C2, an offset power source V2, and switches SW2-1 and SW2-2, and receives a reset signal from the average calculation unit 324 shown in FIG. Then, SW2-2 is closed and the capacitor C1 is fully discharged.

  Here, when the pulse 3T-P is input from the code discriminator 320 shown in FIG. 33, the switch SW2-1 is closed in accordance with this pulse length, the capacitor C2 is charged, and the pulse is turned on. The output voltage of the capacitor C2 increases by a corresponding amount.

  On the other hand, when the linear velocity correction amount Lv3T is input from the linear velocity correction unit 326 shown in FIG. 33, the offset voltage V2 changes, and the output voltage of the charging TV conversion circuit 332 changes by this correction amount.

  The voltage followers 334-1 and 334-2 buffer the output voltages of the discharge TV conversion circuit 330 and the charge TV conversion circuit 332, respectively. Here, when the output of the discharge TV conversion circuit 330 at full charge is 3V, and the amount charged / discharged by the 3T-P pulse is 0.78V, the output a1 of the voltage follower 344-1 is 3V. −0.78V = 2.22V, and the output a2 of the voltage follower 344-2 becomes 0.78V.

  Adders 336-1 and 336-2 add -Vcc / 2 and Vcc / 2 to the outputs of voltage followers 344-1 and 344-2, respectively. Here, when the outputs of the voltage followers 344-1 and 344-2 are 2.22V and 0.78V, respectively, the output b1 of the adder 336-1 is 2.22V-1.5V = 0. The output b2 of the adder 336-2 becomes 0.78V + 1.5V = 2.28V.

  The differential detection circuit 338 performs a difference operation between the output of the adder 366-1 and the output of the adder 366-2, and outputs a voltage value 3T-V. When the outputs of the adders 366-1 and 366-2 are 0.72V and 2.28V, respectively, the output c of the differential detection circuit 338 is 2.28V−0.72V = 1.56V. Note that the output voltage of the differential detection circuit 338, that is, a voltage value including a variation in pulse length may be amplified.

  FIG. 36 is a timing chart showing an example of changes in output voltages of the discharge TV conversion circuit 330 and the charge TV conversion circuit 332 shown in FIG. When a 3T pulse is input at the timing shown in FIG. 11A, the discharge TV conversion circuit 330 repeats the discharge in synchronization with the rise of the pulse, as shown in FIG. The chargeable TV conversion circuit 332 repeats charging in synchronization with the rising edge of the pulse, as shown in FIG.

  In this way, by discharging and charging each time a pulse is input, information in which the total length of a plurality of pulses is integrated as a voltage value can be obtained. By dividing the voltage value integrated in this way by the number of input pulses, the average length of one pulse can be obtained. By comparing this average length with the reference length of the pulse, the average value of the deviation amounts is obtained. Since it can be obtained, real-time correction of the recording condition based on the amount of grazing can be performed.

  In the above-described example, the configuration example in which the sliced RF signal is TV-converted has been described. However, a tangential push-pull signal or a differential value thereof may be TV-converted.

  FIG. 37 is a circuit block diagram showing another embodiment for detecting the lengths of pits and spaces. The present embodiment is an example in the case where the pulse edge portion where the influence of the deviation amount is the largest is selectively extracted to improve the detection capability.

  In the circuit block shown in the figure, the binarized signal SL RF-Sub ′ output from the slicer 210 and the gate signal Gate output from the pulse generation circuit 300 in FIG. . The AND operator 422 outputs the logical product of these input signals to the EXOR operator 440.

  The EXOR operator 440 calculates the exclusive OR of the output of the AND operator 422 and the pulse corresponding to the central part of the pulse corresponding to the detection target code, and outputs the result to the amplifier 422. The example shown in the figure is an example in the case where the detection target code is 6T, and the signal indicated as “6T middle” in the figure is a hollow pulse corresponding to the central portion of the 6T pulse. The hollow pulse corresponding to the central portion can be formed by extracting a portion corresponding to 6T from the recording pulse pattern sequence and uniformly reducing it by 1 to 2T from both edges of the extracted 6T pulse.

  The output of the EXOR operator 440 is a pulse from which the edge portion of the 6T pulse is extracted, and this pulse is multiplied by k by the amplifier 442, output to the TV converter 322 for 6T detection, and integrated in an analog manner.

  FIG. 38 is a timing chart showing a processing example of the circuit block shown in FIG. As shown in FIG. 6A, the signal RF-Sub ′ input to the slicer 210 is binarized at a certain level to generate a pulse signal SL RF-Sub ′ as shown in FIG. Is done.

  Then, a logical product with the gate signal Gate shown in FIG. 1C generated by the pulse generation circuit 300 shown in FIG. 1 is taken to extract a 6T portion to be detected, and then ( The exclusive OR with the mid-pulse 6T Middle corresponding to the center of 6T shown in d) is taken to generate the edge signal 6T Edge shown in FIG.

  Finally, as shown in FIG. 5F, an edge signal is generated by amplifying the 6T Edge signal by the amplifier 422 shown in FIG. This edge signal is a signal obtained by extracting both edge portions Δ of the 6T pulse to be detected, and includes many shift amount elements. Therefore, the detection capability can be improved by performing TV conversion on this edge signal.

  According to the present invention, real-time correction with higher accuracy is possible, so that it is expected to be applied to a recording environment in which recording conditions change on the inner and outer circumferences of an optical disc.

It is a block diagram which shows the internal structure of the drive based on this invention. It is a disassembled perspective view which shows the structure of the pick-up part integrated in the drive shown in FIG. It is a top view which shows arrangement | positioning of the spot irradiated on the disk surface of an optical disk. It is a conceptual diagram which shows the relationship between the spot irradiated on the disk surface of an optical disk, and a detector. It is a conceptual diagram which shows the relationship between the shape of a recording pulse, and a stable area | region. FIG. 2 is a circuit block diagram illustrating an internal configuration of a pulse generation circuit illustrated in FIG. 1. It is a timing chart which shows the production | generation concept of the gate signal shown in FIG. FIG. 2 is a circuit diagram showing an internal configuration of the LD driver shown in FIG. 1. FIG. 2 is a circuit block diagram showing an internal configuration of a mask circuit shown in FIG. 1. It is a timing chart which shows the relationship between a recording pulse, a gate pulse, and a reproduction signal. It is a conceptual diagram which shows the production | generation method of the flag signal which CPU shown in FIG. 1 performs. It is a timing chart which shows the relationship between the main beam for recording, and the sub beam for reproduction | regeneration. 4 is a timing chart showing a relationship between a recording pulse, a pulse obtained by delaying the recording pulse, and an RF signal. It is the block diagram which showed the example of the method of detecting a short pit or space during recording of a long pit. FIG. 15 is a block diagram illustrating a relationship between the counter 256 illustrated in FIG. 14 and the pulse generation circuit 300 illustrated in FIG. 1. FIG. 15 is a conceptual diagram illustrating an example when the buffer 250-2 illustrated in FIG. 14 accumulates a bit string. It is a conceptual diagram which shows the variation of 4T space used as a detection target during recording of 14T pits. It is the block diagram which showed another example of the method of detecting a short pit or space during recording of a long pit. FIG. 19 is a timing chart illustrating a processing example of the circuit block illustrated in FIG. 18. FIG. It is a conceptual diagram which shows the criterion of the determination signal produced | generated by the circuit block of FIG. It is the block diagram which showed another example of the method of detecting a short pit or space during recording of a long pit. FIG. 22 is a timing chart illustrating a processing example of the circuit block illustrated in FIG. 21. 22 is a timing chart illustrating a processing example of the reset pulse generation circuit 426 illustrated in FIG. 21. FIG. 5 is a circuit block diagram showing another configuration example of the mask circuit shown in FIG. 1. FIG. 25 is a first timing chart showing the operation of the circuit shown in FIG. 24. FIG. FIG. 25 is a second timing chart showing the operation of the circuit shown in FIG. 24. FIG. It is a graph which shows the relationship between the differential value of the tangential push pull signal regarding the pit and space calculated | required in the test area | region, and actual physical length. It is a graph which shows the relationship between the differential value of the tangential push pull signal regarding the pit and space calculated | required in the recording area, and the differential value of the tangential push pull signal regarding the pit and space calculated in the recording area. It is the conceptual diagram which showed an example of the test recording performed in order to obtain the differential value of the tangential push pull signal in a test area | region. It is the conceptual diagram which showed an example of the test recording performed in order to obtain the differential value of the tangential push pull signal in a recording area. FIG. 31 is a conceptual diagram illustrating an example in which a recording pulse is corrected using a difference between tangential push-pull signals illustrated in FIG. 30. FIG. 5 is a circuit block diagram showing another configuration example of the mask circuit shown in FIG. 1. It is a circuit block diagram which shows another embodiment which detects the length of a pit and a space. It is a timing chart which shows operation | movement of the code | symbol discriminator shown in FIG. It is a circuit diagram which shows the structure of TV converter shown in FIG. 36 is a timing chart showing an example of changes in output voltage of the discharge TV conversion circuit 330 and the charge TV conversion circuit 332 shown in FIG. 35. It is a circuit block diagram which shows another embodiment which detects the length of a pit and a space. FIG. 38 is a timing chart showing a processing example of the circuit block shown in FIG. 37. FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 20 ... Laser beam, 20A ... Main beam for recording, 20B ... Leading sub beam for tracking, 20C ... Trailing sub beam for tracking, 20D ... Leading sub beam for playback, 20E ... Trailing sub beam for playback, 22 ... Reflected light, 50 ... High Output region 52 ... Low output region 54 ... Constant output region 100 ... Drive 110 ... Laser diode 112 112 Collimator lens 114 ... Diffraction grating 115 ... Groove 116116Half mirror 118 ... Objective lens 120 ... Light receiving lens, 122 ... Detector, 124 ... LD driver, 126 ... Synthesizer, 210 ... Slicer, 212 ... CPU, 214 ... Memory, 216 ... EFM encoder / decoder, 218 ... Interface circuit, 250 ... Buffer, 252 ... Conversion table, 254 ... Delay device, 256 ... Counter, 258 ... 4T decoder, 259 ... 4T decoder, 300 ... pulse generation circuit, 310 ... pulse unit generation circuit, 314 ... inversion circuit, 316 ... AND calculator, 320 ... sign identifier, 322 ... TV converter, 324 ... average calculator, 326: Linear velocity correction unit, 330: Discharge type TV conversion circuit, 332: Rechargeable TV conversion circuit, 334 ... Voltage follower, 336 ... Adder, 338 ... Differential detection circuit, 400 ... Mask circuit, 410 ... AND operation 420, inverting circuit, 422, AND operator, 424, counter, 426, reset pulse generation circuit, 430, tangential push-pull signal generation circuit, 432, VGA circuit, 434, differentiation circuit, 436, RF signal generation circuit 440 ... EXOR operator, 442 ... amplifier, 500 ... optical disc, 502 ... group, 504 Land, 506 ... pit, 508 ... space, 600 ... personal computer

Claims (6)

In an optical information recording apparatus for forming pits and spaces in an optical recording medium by irradiating a laser beam based on a recording pulse including a plurality of types of code information,
Means for reproducing pits and spaces recorded in the medium;
Means for generating a pulse signal including only a predetermined code binarized from the signal obtained by the reproduction;
Means for generating a hollow pulse disposed at a central portion of the predetermined code that is shorter than a pulse length corresponding to the predetermined code;
Means for generating an edge pulse obtained by extracting an edge portion of the pulse signal using the hollow pulse. In an optical information recording apparatus for forming pits and spaces in an optical recording medium by irradiating a laser beam based on a recording pulse including a plurality of types of code information,
Means for reproducing pits and spaces recorded in the medium;
Means for generating a pulse signal including only a predetermined code binarized from the signal obtained by the reproduction;
Means for generating an edge pulse obtained by extracting an edge portion of the pulse signal;
Means for converting the edge pulse into a voltage value by repeating charging and / or discharging according to the edge pulse;
Means for dividing the voltage value by the number of pulses contained in the pulse signal;
An optical information recording apparatus comprising: In an optical information recording apparatus for forming pits and spaces in an optical recording medium by irradiating a laser beam based on a recording pulse including a plurality of types of code information,
Means for reproducing pits and spaces recorded in the medium;
Means for generating a pulse signal including only a predetermined code binarized from the signal obtained by the reproduction;
Means for generating an edge pulse obtained by extracting an edge portion of the pulse signal;
Means for converting the edge pulse into a voltage value by repeating charging and / or discharging according to the edge pulse;
Means for detecting a length shift amount of pits and / or spaces formed in the medium by dividing the voltage value by the number of pulses included in the pulse signal;
An optical information recording apparatus comprising: 4. The optical information recording apparatus according to claim 3 , further comprising means for amplifying the edge pulse, and performing voltage conversion of the edge pulse using the amplified signal. In an optical information recording method for forming pits and spaces in an optical recording medium by irradiating a laser beam based on a recording pulse including a plurality of types of code information,
Playing back pits and spaces recorded on the media;
Generating a pulse signal including only a predetermined code binarized from the signal obtained by the reproduction;
Generating an edge pulse obtained by extracting an edge portion of the pulse signal;
Repeating the charging and / or discharging according to the edge pulse to convert the edge pulse into a voltage value;
Dividing the voltage value by the number of pulses included in the pulse signal to detect a length shift amount of pits and / or spaces formed in the medium;
An optical information recording method comprising: In a signal processing circuit incorporated in an optical information recording apparatus that forms pits and spaces in an optical recording medium by irradiating a laser beam based on a recording pulse including a plurality of types of code information,
Means for reproducing pits and spaces recorded in the medium;
Means for generating a pulse signal including only a predetermined code binarized from the signal obtained by the reproduction;
Means for generating a hollow pulse disposed at a central portion of the predetermined code that is shorter than a pulse length corresponding to the predetermined code;
And a means for generating an edge pulse obtained by extracting an edge portion of the pulse signal using the hollow pulse.

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