JP2010257531A - Land prepit detection method, and information recording/reproducing device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent false detection of a land prepit when an abrupt change occurs in push-pull signal amplitude and offset. <P>SOLUTION: In addition to a first offset generator 10 for continuously adding a first offset OFS1 to a wobble peak detection signal WPK, a second offset generator 103 is provided to generate a second offset OFS2 to be added to a wobble peak detection signal OPK with the first offset added thereto, only when a change detection signal SW1 of a push-pull signal PP is active. In an adder 12, the second offset OFS2 is added to the wobble peak detection signal OPK with the first offset added thereto. In a comparator 13, a slice reference signal LTH1 as a reference for detecting the land prepit is generated. False detection of the land prepit is prevented by making potential of the slice reference signal LTH1 in a period of the push-pull signal PP having the abrupt change higher than a peak level of the push-pull signal PP. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method and apparatus for recording information on an optical disc, and more particularly, to a method for detecting prepit information during information recording and reproduction on an optical disc.

  In an information recording medium using an optical disc, a reference signal for generating a clock signal used for a recording / reproducing operation and address information are formed in advance in order to enable recording / reproducing of information. One format is DVD-R / RW.

  In DVD-R / RW, a groove (also referred to as a guide groove) of a disk for recording / reproducing information is provided with a wobble that is oscillated in a radial direction at a constant frequency, and obtained based on this wobble. The wobble signal is used as a reference signal for generating a clock for recording and reproducing information and an optical disc rotation control signal. The wobble signal is divided into at least two parts so that the optical disk is irradiated with a light beam, followed by a grooved track, and the reflected light can be received from the inner and outer peripheral sides of the optical disk with respect to the track. It is generated on the basis of a differential signal (hereinafter referred to as a push-pull signal) that is converted into an electrical signal by the photoelectric element and takes the difference between the reflected signals from the inner and outer peripheral sides. In DVD-R / RW, prepits are formed in land portions between grooves (hereinafter referred to as land prepits), and a land prepit signal generated based on the land prepit formation position is: When recording and reproducing information, it is used as address information indicating a physical position on the optical disc. The land pre-pit signal is generated based on the push-pull signal in the same manner as the wobble signal.

  The land pre-pit is formed so as to be positioned at the top of the wobble. As shown in FIG. 21A, the land pre-pit signal components SLP1, SLP2, and SLP3 are superimposed on the top of the wobble signal component WBL. Will be. Therefore, the extraction of the land pre-pit signal component from the push-pull signal can be realized by performing binarization processing with a predetermined slice level as the threshold value VTH, and this binarized signal becomes the land pre-pit signal SLPP.

  However, when a recording mark is formed in the groove by recording, the reflectance of the recording mark portion becomes low and the amplitude level of the land pre-pit signal becomes small. In addition, the push-pull signal has fluctuations in the signal amplitude and DC component due to the influence of crosstalk from adjacent tracks or variations in disk quality, and instability of the track following operation, and the slice level is set to a fixed value. Then, there is a problem that a small-amplitude land pre-pit signal in the recording mark portion cannot be detected or a noise component included in the push-pull signal is erroneously detected as a land pre-pit signal. That is, in FIG. 21A, although the SLP1 is normally detected as the land pre-pit signal SLPP, a noise component in the vicinity of the SLP2 is erroneously detected, and the potential of the SLP3 is higher than the threshold value VTH. Since it is low, it cannot be detected.

  Patent Document 1 discloses a land pre-pit detection method for solving the above-described problem. As shown in FIG. 21 (b), the wobble signal component WBL of the push-pull signal is peak detected, and the wobble peak is detected. This is a method in which a binarization process is performed using a signal obtained by adding a predetermined offset SOFS to the detection signal SWPK as a slice level threshold value STH, and the binarized signal is used as a land pre-pit signal SLPP. According to this method, as indicated by the land pre-pit signal SLPP in FIG. 21B, it is possible to avoid erroneous detection of noise in the vicinity of SLP2, which has occurred in FIG.

JP 2004-134002 A

  Here, for example, the switching point from the reproduction operation to the recording operation, the switching point from the reproduction of the unrecorded area to the reproduction of the recorded area, the reproduction of the defective area due to dirt or scratches attached to the optical disk, etc. When there is a change in laser power or amount of reflected light, such as when switching to a non-defect area, there is a circuit when gain switching is performed for an amplifier element that generates a push-pull signal to keep the push-pull signal amplitude constant. Depending on the response, the amplitude and DC component of the push-pull signal may fluctuate abruptly.

  However, in the land pre-pit detection method according to Patent Document 1, the circuit for detecting the peak of the wobble signal component is composed of a peak hold circuit with poor followability that does not respond to a sharp rising or falling noise of the waveform. As shown in part A of FIG. 22, when the amplitude or offset of the push-pull signal changes steeply, the peak detection operation cannot follow the change, and the wobble peak detection signal SWPK shows an accurate wobble peak value. The wobble signal component and noise component included in the push-pull signal may be erroneously detected as the land pre-pit signal SLPP.

  As a result, an error occurs in the address information, the seek operation performance is deteriorated, and the data recording position shift immediately after the start of recording occurs, resulting in a decrease in reproduction performance.

  In other words, in the seek operation, the land pre-pit signal is erroneously detected, and erroneous address information is acquired, so that it is erroneously recognized that a place that is not the desired position is being reproduced, and the vicinity of the desired position is reproduced. However, there is a problem that an unnecessary operation of performing a seek operation again occurs and the seek time becomes long.

  In addition, in the data recording operation, when new data is additionally recorded subsequent to the written data on an optical disk on which a part or a part of the data has already been written, There may be a phase difference between the recording clock used and the recording clock for additional recording, and phase correction of the recording clock is performed using the address information obtained from the land prepit signal. Although there is a method of performing this, if there is an error in the information of this address signal, normal phase correction is not performed. In this case, when the optical disk after additional recording is reproduced, the interval of the synchronization signal recorded with the data differs from the interval in the other recorded areas, and the synchronization signal cannot be detected and data reproduction is performed normally. There may not be. Alternatively, as a method of generating a reproduction clock that becomes an operation clock at the time of data reproduction, it is conceivable to use a PLL (Phase Locked Loop) circuit with reproduction data as an input. In this case, before and after the joint of additional recording, Phase and frequency differences occur in the recording clock, the synchronization operation of the PLL circuit is disturbed, and the reproduction data is erroneously detected when the reproduction data is decoded based on the reproduction clock, so that the data reproduction is performed normally. Thus, the readability is reduced, and in the worst case, additional recorded data may not be reproducible.

  Also, in order to avoid abrupt fluctuations in the amplitude and DC component that occur in push-pull signals, the gain setting is finely varied and the response speed is increased as a circuit until push-pull signal generation, etc. Although there is a method using the method, the circuit area and power consumption become large.

  An object of the present invention is to prevent erroneous detection of a land pre-pit signal even when there is a steep fluctuation such as an amplitude or offset of a push-pull signal.

  In order to solve the above problems, the present invention irradiates a laser beam to an information recording medium in which tracks on which information is recorded are formed by meandering grooves, and address information is recorded in lands between the grooves by prepits. Then, in a device that generates a push-pull signal including a wobble signal component and a land pre-pit signal component from the reflected light and detects a land pre-pit from the push-pull signal, peak detection of the wobble signal component included in the push-pull signal is performed. The wobble peak detection means for performing the offset, the offset generation means for variably generating the offset signal potential to be added to the wobble peak detection signal, the wobble peak detection signal and the variable offset signal are added, Means for generating a slice signal as a reference for pit detection; And a land pre-pit generation means for comparing the pull-up signal and the slice signal and outputting the comparison result as a land pre-pit signal, and the potential of the offset signal according to the switching point of the push-pull signal state or the device operation state. The slice signal potential can be varied by changing.

  As a result, even when the push-pull signal has steep fluctuations such as amplitude and offset, the slice signal level in that period is at a potential higher than the peak level of the push-pull signal. It is possible to avoid erroneous detection of noise components other than the pit signal as the land pre-pit signal.

  As a result, it is possible to prevent a decrease in seek performance as an information recording / reproducing apparatus and a decrease in reproduction performance due to a data recording position shift immediately after the start of recording.

It is a block diagram which shows the structure of the information recording / reproducing apparatus by Embodiment 1 of this invention. It is a figure which shows the signal waveform of each part in the information recording / reproducing apparatus shown in FIG. It is a block diagram which shows the structure of the information recording / reproducing apparatus by Embodiment 2 of this invention. It is a figure which shows the signal waveform of each part in the information recording / reproducing apparatus shown in FIG. It is a block diagram which shows the structure of the information recording / reproducing apparatus by Embodiment 3 of this invention. It is a figure which shows the signal waveform of each part in the information recording / reproducing apparatus shown in FIG. It is a block diagram which shows the structure of the information recording / reproducing apparatus by Embodiment 4 of this invention. It is a figure which shows the signal waveform of each part in the information recording / reproducing apparatus shown in FIG. It is a block diagram which shows the structure of the information recording / reproducing apparatus by Embodiment 5 of this invention. It is a figure which shows the signal waveform of each part in the information recording / reproducing apparatus shown in FIG. It is a block diagram which shows the structure of the information recording / reproducing apparatus by Embodiment 6 of this invention. (A) And (b) is a figure which shows the signal waveform of each part in the information recording / reproducing apparatus shown in FIG.1 and FIG.11. It is a block diagram which shows the structure of the information recording / reproducing apparatus by Embodiment 7 of this invention. (A) And (b) is a figure which shows the signal waveform of each part in the information recording / reproducing apparatus shown in FIG.7 and FIG.13. It is a block diagram which shows the structure of the information recording / reproducing apparatus by Embodiment 8 of this invention. (A) And (b) is a figure which shows the signal waveform of each part in the information recording / reproducing apparatus shown in FIG.1 and FIG.15. It is a block diagram which shows the structure of the information recording / reproducing apparatus by Embodiment 9 of this invention. (A) And (b) is a figure which shows the signal waveform of each part in the information recording / reproducing apparatus shown in FIG.1 and FIG.17. It is a block diagram which shows the structure which produces | generates a recording clock in the information recording / reproducing apparatus by Embodiment 10 of this invention. It is a block diagram which shows the structure regarding seek operation control in the information recording / reproducing apparatus by Embodiment 10 of this invention. (A) And (b) is a figure which shows the signal waveform at the time of the land prepit detection by the conventional information recording / reproducing apparatus. It is a figure which shows the signal waveform at the time of the land prepit detection in case there exists a steep fluctuation | variation in the push pull signal by the conventional information recording / reproducing apparatus.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each of the following embodiments, components having functions similar to those of the other embodiments are denoted by the same reference numerals and description thereof is omitted.

Embodiment 1
Hereinafter, Embodiment 1 of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an information recording / reproducing apparatus according to Embodiment 1 of the present invention. As shown in FIG. 1, in the information recording / reproducing apparatus according to Embodiment 1 of the present invention, an optical pickup 2 is provided, and a laser beam output from a laser diode 3 built in the optical pickup 2 has land prepits. For example, information is recorded and reproduced by irradiating the optical disk 1 made of DVD-R or DVD-RW. The laser light is controlled to have a larger power at the time of recording than at the time of reproduction in accordance with an instruction from a CPU (Central Processing Unit) 7 that controls the system operation to the laser power control unit 8.

  In addition, the optical pickup 2 incorporates at least a light receiving element 4 divided into an inner peripheral side and an outer peripheral side of the optical disc 1 (described in FIG. 1 is divided into four parts). The light receiving element 4 receives the reflected light when the optical disk 1 is irradiated with the laser light, and converts the current generated in each divided area into a voltage (IV conversion). Then, the addition of the inner peripheral voltage and the addition of the outer peripheral voltage are performed by the addition amplifiers 5a and 5b, and an inner peripheral addition signal and an outer peripheral addition signal are output, respectively. The subtraction amplifier 6 performs subtraction between the addition signal on the inner circumference side and the addition signal on the outer circumference side, the recording pulse component is removed during recording, and the RF (Radio Frequency) component consisting of the reproduction signal is reproduced during reproduction of the recorded area. The removed difference signal is generated and output as a push-pull signal PP. In addition to the wobble signal component and the land pre-pit signal component, the push-pull signal PP includes a deviation of reflected light and a variation in IV conversion corresponding to each region of the light receiving element 4, or gains of the addition amplifiers 5a and 5b. Recording pulses and RF residual components that could not be removed by the subtraction amplifier 6 due to relative variation are superimposed as noise.

  Here, at the time of recording, since the laser power is larger than that at the time of reproduction as described above, the amount of reflected light from the optical disc 1 is increased and the voltage level from the light receiving element 4 is also increased. Therefore, since the signal amplitude of each part thereafter increases, in order to perform signal processing with effective use of the dynamic range of the circuit and good S / N, the IV conversion in the light receiving element 4 or the addition amplifier 5a and Generally, the gain is switched by 5b or the subtracting amplifier 6 to keep the signal amplitude constant during recording and during reproduction.

  Further, when the recorded area is reproduced even during reproduction, the amount of reflected light of the recording mark portion that is generated when information is recorded on the optical disc 1 is lower than that of the space portion where no information is recorded. Therefore, since the signal amplitude of each part changes between the recorded area and the unrecorded area, the gain conversion is performed by the IV conversion in the light receiving element 4, or the addition amplifiers 5a and 5b, or the subtraction amplifier 6 as in the recording. Switching is performed to perform processing for keeping the signal amplitude constant during reproduction of the recorded area and during reproduction of the unrecorded area.

  The gain switching at the time of recording and reproduction is performed by an instruction from the CPU 7, for example. However, the push-pull signal PP is changed due to the responsiveness of each unit, the accuracy of gain switching, and the output offset amount that varies depending on the gain setting of each unit. Steep amplitudes and DC component fluctuations may occur.

  Alternatively, if there is a defect area where dirt, scratches, etc. are attached to the optical disc 1, the amount of reflected light is reduced compared to a non-defect area where there is no dirt, scratches, etc. Therefore, when the optical pickup 2 passes from the defect area to the non-defect area in the reproducing operation, abrupt fluctuations occur in the amplitude of the push-pull signal PP obtained at that time.

  The push-pull signal fluctuation detection unit 102 detects fluctuations in amplitude and DC component that occur in the push-pull signal PP. As the detection method, for example, peak detection and bottom detection of the push-pull signal PP are performed, and the amplitude value of the push-pull signal PP is obtained by subtracting the bottom detection value from the peak detection value. If it is, the H level is output as the fluctuation detection signal SW1, assuming that there is an amplitude fluctuation. Further, the center value of the peak detection value and the bottom detection value is obtained as the offset value of the push-pull signal, and when the offset value is equal to or higher than a predetermined level, the H level is assumed to have a DC component fluctuation and the fluctuation detection signal SW1. Output as. The determination value of whether or not the amplitude value and the offset value of the push-pull signal PP are varied is determined in consideration of the gain setting amount that is variable in each unit and the output offset amount that can be generated by each unit. Alternatively, the push-pull signal fluctuation detection unit 102 may have a fixed value in advance.

  The delay device 101 delays the push-pull signal PP so that the fluctuation detection signal SW1 from the push-pull signal fluctuation detection unit 102 can be reflected in a land pre-pit generation process to be described later, and outputs the push-pull signal PPd after the delay. The delay amount DL1 is determined in consideration of the response time until the push-pull signal fluctuation detection unit 102 detects the fluctuation of the push-pull signal PP and changes the fluctuation detection signal SW1 from the L level to the H level. That's fine.

  The delayed push-pull signal PPd is input to the wobble peak detection unit 9. The wobble peak detection unit 9 is configured to have a tracking characteristic for detecting the peak value of the wobble signal component without following the land pre-pit signal component included in the delayed push-pull signal PPd. A peak detection signal WPK is output.

  The first offset generator 10 is for generating a first offset OFS1 to be applied to the wobble peak detection signal WPK in order to make it easy to stably detect land prepits. The adder 11 detects wobble peak. The signal WPK and the first offset OFS1 are added to generate a wobble peak detection signal OPK after the first offset addition. The offset amount of the first offset generation unit 10 is a state in which the push-pull signal PP is not abruptly changed, and a wobble signal component included in the push-pull signal PP, a noise component (the above-described residual recording pulse component during recording, The first offset generation unit 10 has a fixed value that can slice only the land pre-pit signal component without slicing the remaining RF component of the recorded area) by the comparator 13 described later and erroneously detecting it as a land pre-pit. Alternatively, it may be configured to change according to an instruction from the CPU 7 so as to improve the detection rate of land pre-pits.

  The second offset generator 103 is for generating a second offset OFS2 to be applied to the wobble peak detection signal OPK after the first offset addition when the push-pull signal PP has a steep fluctuation. The second offset OFS2 is output only when the signal SW1 is at the H level.

  The adder 12 adds the wobble peak detection signal OPK after the first offset addition and the second offset OFS2, and generates a slice reference signal LTH1 serving as a reference for detecting a land prepit.

  Here, the offset amount of the second offset generation unit 103 is obtained by adding a gain setting amount that is variable in each unit and an output offset amount that can be generated by each unit in a state where the push-pull signal PP is abruptly changed. The second offset generation unit 103 may have a fixed value determined in advance so that the potential of the reference signal LTH1 is higher than the peak level including the land pre-pit signal component of the push-pull signal PP, or the CPU 7 The fixed value may be set in the second offset generation unit 103 according to an instruction from.

  The non-inverted input of the comparator 13 is configured to receive the delayed push-pull signal PPd, and the inverted input is configured to receive the slice reference signal LTH1. With this configuration, when the voltage level of the delayed push-pull signal PPd is higher than the voltage level of the slice reference signal LTH1, the comparator 13 outputs an H level. When there is no land pre-pit signal component, the L level is output as the land pre-pit signal LPP.

  FIG. 2 shows the waveforms of the parts denoted by the reference numerals in FIG. 1 regarding the land pre-pit detection operation when the push-pull signal PP has a steep fluctuation according to the first embodiment of the present invention. The push-pull signal PP generated by the subtracting amplifier 6 is detected by the push-pull signal fluctuation detection unit 102. In this case, a portion where the amplitude fluctuation of the push-pull signal PP is large is detected, and the fluctuation detection signal SW1 is at the H level.

  On the other hand, the push-pull signal PPd after the delay of the push-pull signal PP by the delay amount DL1 is input to the wobble peak detection unit 9, and the wobble peak detection signal WPK is output. When the fluctuation detection signal SW1 is L level with respect to the wobble peak detection signal WPK, only the first offset OFS1 from the first offset generator 10 is applied, and the fluctuation detection signal SW1 is H level. In addition to the first offset OFS1, the second offset OFS2 from the second offset generation unit 103 is applied to generate the slice reference signal LTH1.

  After that, when the delayed push-pull signal PPd by the comparator 13 is sliced by the slice reference signal LTH1, if the push-pull signal PP has no steep fluctuation and the fluctuation detection signal SW1 is at the L level, the slice reference signal LTH1 Is lower than the land pre-pit signal component included in the delayed push-pull signal PPd and higher than the wobble signal component and noise component included in the delayed push-pull signal PPd. Accordingly, an H level signal can be output as the land pre-pit signal LPP. On the other hand, when the push-pull signal PP has a steep fluctuation and the fluctuation detection signal SW1 becomes H level, the potential of the slice reference signal LTH1 becomes higher than the delayed push-pull signal PPd. Wobble signal components and noise components included in PP are not erroneously detected as land pre-pit signals LPP.

  In the first embodiment of the present invention, push-pull such as a switching point between a reproduction operation and a recording operation, a switching point between reproduction of an unrecorded area and reproduction of a recorded area, or a switching point from a defect area to a non-defect area, etc. Even if the signal PP has a steep fluctuation, erroneous detection of the land pre-pit signal LPP can be avoided.

<< Embodiment 2 >>
Embodiment 2 of the present invention will be described below with reference to the drawings. FIG. 3 is a block diagram showing an information recording / reproducing apparatus according to Embodiment 2 of the present invention. The difference from the information recording / reproducing apparatus according to Embodiment 1 shown in FIG. The recording section gate signal generation section 202 and the reproduction operation / recording operation switching point detection section 203 are provided without the section 102.

  FIG. 4 shows the land pre-pit detection operation when the push-pull signal PP has a steep fluctuation at the switching point from the reproduction operation to the recording operation according to the second embodiment of the present invention. The waveform of each part is shown.

  In FIG. 3, the recording section gate signal generation unit 202 receives an instruction from the CPU 7 and generates a recording section gate signal GT2 having a different potential from that during the reproducing operation when performing the recording operation. For example, as shown in FIG. It outputs L level during playback and H level during recording.

  Here, at the switching point between the reproduction operation and the recording operation, the power of the laser beam output from the optical pickup 2 varies, and therefore the amount of reflected light from the optical disc 1 varies, so that the push-pull signal PP varies sharply. It can happen. Therefore, the recording operation gate signal GT2 is input to the reproduction operation / recording operation switching point detection unit 203, and the edge is detected. For example, as shown in FIG. 4, as the reproduction operation / recording operation switching point detection signal SW2, An H level is output, and a signal that becomes an L level after a lapse of a predetermined time T when a steep fluctuation is stabilized in the push-pull signal PP is generated. Note that the predetermined time T is a laser power difference, a gain setting amount that can be changed in each part, an output offset amount that can be generated by each part, and a response characteristic at the time of gain switching of each part, which can be assumed during the reproduction operation and the recording operation. It may be determined in consideration and given from the CPU 7 or may be configured to have a fixed value in the reproduction operation / recording operation switching point detection unit 203 in advance.

  On the other hand, the push-pull signal PP is input to the wobble peak detection unit 9, and a wobble peak detection signal WPK is output as shown in FIG. When the reproduction / recording operation switching point detection signal SW2 is L level with respect to the wobble peak detection signal WPK, only the first offset OFS1 from the first offset generator 10 is applied, and the reproduction operation / When the recording operation switching point detection signal SW2 is at the H level, the second offset OFS2 from the second offset generator 103 is applied in addition to the first offset OFS1, and the slice reference signal LTH2 is generated.

  Thereafter, when the push-pull signal PP is sliced with the slice reference signal LTH2 by the comparator 13, if the push-pull signal PP is not sharply changed and the reproduction operation / recording operation switching point detection signal SW2 is at the L level, the slice is sliced. Since the potential of the reference signal LTH2 is lower than the land pre-pit signal component included in the push-pull signal PP and larger than the wobble signal component and noise component included in the push-pull signal PP, the potential depends on the land pre-pit signal component. An H level signal can be output as the land pre-pit signal LPP. On the other hand, when the push-pull signal PP has a steep fluctuation and the reproduction operation / recording operation switching point detection signal SW2 becomes H level, the potential of the slice reference signal LTH2 becomes higher than the push-pull signal PP. The wobble signal component and noise component included in the push-pull signal PP are not erroneously detected as the land pre-pit signal LPP.

  Note that the response speed of generation of the recording period gate signal GT2 by the recording period gate signal generation unit 202 is slow, and the rising position of the reproduction operation / recording operation switching point detection signal SW2 is slower than the sharp fluctuation position of the push-pull signal PP. In such a case, for example, as shown in the first embodiment, the delay unit 101 is provided in the preceding stage of the wobble peak detection unit 9 and the comparator 13, and the wobble detection operation using the delayed push-pull signal is performed. The generation operation of the slice reference signal LTH2 and the generation operation of the land pre-pit signal LPP may be performed. Alternatively, since the switching operation between the recording operation and the reproducing operation is based on an instruction from the CPU 7, the recording interval gate signal GT2 may be output before the switching operation between the actual recording operation and the reproducing operation. .

  In the second embodiment of the present invention, erroneous detection of the land pre-pit signal LPP can be avoided even if the push-pull signal PP has a sharp fluctuation at the switching point between the reproducing operation and the recording operation.

  The recording section gate signal GT2 is also used in other components not shown in FIG. 3 as an information recording / reproducing apparatus, such as control of whether or not recording data is output. The signal generation unit 202 does not need to be newly provided in order to realize the present embodiment, and the reproduction operation / recording operation switching check has a simpler configuration than the push-pull signal fluctuation detection unit 102 provided in the first embodiment. Since the output unit 203 is used, when the information recording / reproducing apparatus according to Embodiment 2 of the present invention is configured with an electric circuit, the circuit area and power consumption can be reduced.

<< Embodiment 3 >>
Hereinafter, Embodiment 3 of the present invention will be described with reference to the drawings. FIG. 5 is a block diagram showing an information recording / reproducing apparatus according to Embodiment 3 of the present invention. The difference from the information recording / reproducing apparatus according to Embodiment 1 shown in FIG. The recording area detection gate signal generation section 302 and the recorded area / unrecorded area switching point detection section 303 are provided without the section 102.

  FIG. 6 is a diagram showing a land pre-pit detection operation when the push-pull signal PP has a steep change at a switching point between reproduction of a recorded area and reproduction of an unrecorded area according to the third embodiment of the present invention. The waveform of each part which attached | subjected the code | symbol to 5 is shown.

  In FIG. 5, the recorded area detection gate signal generation unit 302 receives the reproduction signal from the optical disc 1 as reflected light by the light receiving element 4 and performs IV conversion, and adds the inner circumference addition signal and the outer circumference addition signal. Are input from the summing amplifiers 5a and 5b, respectively, and add processing is performed on the inner peripheral side addition signal and the outer peripheral side addition signal to generate a full addition signal. This full sum signal is a signal in which the wobble signal component and the land pre-pit signal component are substantially removed during the reproduction operation of the recorded area, and the RF component consisting of the reproduction signal becomes the main signal. At the time of operation, since there is no reproduction signal, there is almost no signal. The recorded region detection gate signal generation unit 302 detects whether the region is a recorded region or an unrecorded region using the total addition signal. For example, the peak detection of the total addition signal becomes a peak value equal to or greater than a predetermined value. In the case where the recorded area is recorded, a recorded area gate signal GT3 having a potential different from that in the reproduction operation of the unrecorded area is generated by using a method such as detecting the recorded area. For example, as shown in FIG. The L level is output during the reproduction operation of the completed area, and the H level is output during the reproduction operation of the unrecorded area. Note that the determination value as to whether or not it is a recorded area can be determined in consideration of the gain setting amount that is variable in each unit for generating the full addition signal and the output offset amount that can be generated. Alternatively, the recorded area detection gate signal generation unit 302 may have a fixed value in advance.

  Here, since the reflectivity of the optical disc 1 varies depending on the presence or absence of the recording mark at the switching point between the reproduction of the recorded area and the reproduction of the unrecorded area, there is a possibility that the push-pull signal PP may vary sharply. . For this reason, the recorded area / unrecorded area switching point detector 303 receives the recorded area gate signal GT3 and detects the rising edge thereof. For example, as shown in FIG. 6, the recorded area / unrecorded area is switched. As the point detection signal SW3, an H level is output, and a signal that becomes an L level after a lapse of a predetermined time T when a steep fluctuation is stabilized in the push-pull signal PP is generated. Note that the predetermined time T is assumed to be a recorded area reproduction operation and an unrecorded area reproduction operation, and a gain setting amount that can be changed in each part, an output offset amount that can be generated by each part, and a response at the time of gain switching of each part It may be determined in consideration of characteristics and may be given from the CPU 7 or may have a fixed value in the recorded area / unrecorded area switching point detection unit 303 in advance.

  On the other hand, the push-pull signal PP is input to the wobble peak detection unit 9 and a wobble peak detection signal WPK is output. Then, when the recorded area / unrecorded area switching point detection signal SW3 is at L level with respect to the wobble peak detection signal WPK, only the first offset OFS1 from the first offset generation unit 10 is applied and recorded. When the completed area / unrecorded area switching point detection signal SW3 is at the H level, the second offset OFS2 from the second offset generator 103 is applied in addition to the first offset OFS1, and the slice reference signal LTH3 is generated. .

  Thereafter, when the push-pull signal PP is sliced with the slice reference signal LTH3 by the comparator 13, the push-pull signal PP is not sharply changed and the recorded area / unrecorded area switching point detection signal SW3 is at the L level. Since the potential of the slice reference signal LTH3 is lower than the land pre-pit signal component included in the push-pull signal PP and larger than the wobble signal component and noise component included in the push-pull signal PP, Accordingly, an H level signal can be output as the land pre-pit signal LPP. On the other hand, when the push-pull signal PP has a steep fluctuation and the recorded area / unrecorded area switching point detection signal SW3 becomes H level, the potential of the slice reference signal LTH3 becomes higher than the push-pull signal PP. Therefore, the wobble signal component and the noise component included in the push-pull signal PP are not erroneously detected as the land pre-pit signal LPP.

  It should be noted that the response speed of generation of the recorded area gate signal GT3 by the recorded area detection gate signal generation unit 302 is slow, and the rising position of the recorded area / unrecorded area switching point detection signal SW3 has a steep fluctuation of the push-pull signal PP. In the case where the position is later than the position, for example, as shown in the first embodiment, the delay unit 101 is provided in the preceding stage of the wobble peak detection unit 9 and the comparator 13, and the delayed push-pull signal is used. A wobble detection operation, a slice reference signal LTH3 generation operation, and a land pre-pit signal LPP generation operation may be performed.

  In Embodiment 3 of the present invention, erroneous detection of the land pre-pit signal LPP is avoided even if the push-pull signal PP has a steep fluctuation at the switching point between reproduction of the recorded area and reproduction of the unrecorded area. Can do.

  Further, the recorded area gate signal GT3 is shown in FIG. 5 as an information recording / reproducing apparatus, such as a control for detecting an unrecorded area in order to perform additional recording on an information recording medium once recorded. The recorded region detection gate signal generation unit 302 does not need to be newly provided to realize this embodiment, and the push-pull signal fluctuation provided in the first embodiment is also used. Since the recorded area / unrecorded area switching point detecting unit 303 having a simpler configuration than that of the detecting unit 102 is used, when the information recording / reproducing apparatus according to the third embodiment of the present invention is configured by an electric circuit, the circuit area, Power consumption can be reduced.

<< Embodiment 4 >>
Embodiment 4 of the present invention will be described below with reference to the drawings. FIG. 7 is a block diagram showing an information recording / reproducing apparatus according to Embodiment 4 of the present invention. The difference from the information recording / reproducing apparatus according to Embodiment 1 shown in FIG. The laser power switching point detection unit 403 is provided without the unit 102.

  Further, FIG. 8 shows the waveforms of the respective parts denoted by the reference numerals in FIG. 7 regarding the land pre-pit detection operation when the push-pull signal PP has a steep fluctuation at the laser power switching point according to the third embodiment of the present invention. It is shown.

  In FIG. 7, the laser power control unit 8 receives an instruction from the CPU 7 and generates a laser power change gate signal GT4 having a different potential from that when the laser power is small when increasing the laser power. For example, as shown in FIG. Thus, the L level is output when the laser power is low, and the H level is output when the laser power is increased. Here, the determination of whether the laser power is large or small may be, for example, the difference in laser power between the reproduction operation and the recording operation, or the reproduction signal when there is a change in the reflectance even during the reproduction operation. As long as the information recording / reproducing apparatus is configured to change the laser power in order to read the laser beam stably, the difference in laser power during reproduction may be used.

  Here, since the amount of reflected light from the optical disk 1 fluctuates at the laser power switching point, there is a possibility that a sharp fluctuation occurs in the push-pull signal PP. Therefore, the laser power change point detection unit 403 receives the laser power change gate signal GT4, detects the rising edge thereof, and outputs an H level as the laser power change point detection signal SW4, for example, as shown in FIG. Then, a signal that becomes the L level after the elapse of the predetermined time T in which the steep fluctuation is stabilized in the push-pull signal PP is generated. The predetermined time T is determined in consideration of a laser power difference, a gain setting amount that can be changed in each part, an output offset amount that can be generated in each part, and a response characteristic at the time of gain switching in each part. However, it may be given from the CPU 7 or may have a configuration in which the laser power switching point detection unit 403 has a fixed value in advance.

  On the other hand, the push-pull signal PP is input to the wobble peak detection unit 9, and a wobble peak detection signal WPK is output as shown in FIG. When the laser power switching point detection signal SW4 is L level with respect to the wobble peak detection signal WPK, only the first offset OFS1 from the first offset generator 10 is applied, and the laser power switching point detection signal is detected. When SW4 is at the H level, the second offset OFS2 from the second offset generator 103 is applied in addition to the first offset OFS1, and the slice reference signal LTH4 is generated.

  Thereafter, when the push-pull signal PP is sliced with the slice reference signal LTH4 by the comparator 13, when the push-pull signal PP does not have a steep fluctuation and the laser power switching point detection signal SW4 is at the L level, the slice reference signal LTH4. Is lower than the land pre-pit signal component included in the push-pull signal PP and larger than the wobble signal component and noise component included in the push-pull signal PP. The signal can be output as a land pre-pit signal LPP. On the other hand, when the push-pull signal PP has a steep fluctuation and the laser power switching point detection signal SW4 becomes H level, the potential of the slice reference signal LTH4 becomes higher than the push-pull signal PP. Wobble signal components and noise components included in PP are not erroneously detected as land pre-pit signals LPP.

  It should be noted that the response speed of generation of the laser power change gate signal GT4 by the laser power control unit 8 is slow and the rising position of the laser power switching point detection signal SW4 is slower than the steep fluctuation position of the push-pull signal PP. For example, as shown in the first embodiment, the delay unit 101 is provided in the preceding stage of the wobble peak detection unit 9 and the comparator 13, and the wobble detection operation using the delayed push-pull signal and the slice reference signal LTH4 are performed. The generation operation and the generation operation of the land pre-pit signal LPP may be performed. Alternatively, since the laser power switching operation is based on an instruction from the CPU 7, the laser power change gate signal GT4 may be output before the actual laser power switching operation.

  In the fourth embodiment of the present invention, erroneous detection of the land pre-pit signal LPP can be avoided even if the push-pull signal PP has a steep fluctuation at the laser power switching point.

  In addition, since the laser power switching point detector 403 having a simpler configuration than the push-pull signal fluctuation detector 102 provided in the first embodiment is used, the information recording / reproducing apparatus according to the fourth embodiment of the present invention is implemented by an electric circuit. In the case of the configuration, the circuit area and power consumption can be reduced.

<< Embodiment 5 >>
Embodiment 5 of the present invention will be described below with reference to the drawings. FIG. 9 is a block diagram showing an information recording / reproducing apparatus according to Embodiment 5 of the present invention. Differences from the information recording / reproducing apparatus according to Embodiment 1 shown in FIG. The defect area detection gate signal generation section 502 and the defect area / non-defect area switching point detection section 503 are provided without the section 102.

  FIG. 10 shows the land pre-pit detection operation when the push-pull signal PP has a sharp fluctuation at the switching point between the defect area reproduction and the non-defect area reproduction according to the fifth embodiment of the present invention. The waveform of each part which attached | subjected the code | symbol to is shown.

  In FIG. 9, the defect area detection gate signal generation unit 502 receives the reproduction signal from the optical disc 1 as reflected light by the light receiving element 4 and performs IV conversion, and the addition signal on the inner circumference side and the addition signal on the outer circumference side. Are input from summing amplifiers 5a and 5b, respectively. The defect area detection gate signal generation unit 502 uses the inner peripheral side addition signal and the outer peripheral side addition signal to detect whether there is a defect portion due to dirt or scratches attached to the optical disc 1. For example, by adding the addition signal on the inner circumference side and the addition signal on the outer circumference side, a total addition signal including the RF component is generated in the recorded area, and the addition signal on the inner circumference side and the addition signal on the outer circumference side are generated. To generate a difference signal including a wobble signal component and a land pre-pit signal component, respectively, detect a peak of each of the total addition signal and the difference signal, and an addition signal of each peak signal obtained as a result, If the peak value is less than or equal to a predetermined value, a defect area gate signal having a potential different from that in the non-defect area reproduction operation is used by detecting the defect area. Generates GT5, for example, the reproducing operation of the defective area, as shown in FIG. 10 is L level, the reproducing operation of the non-defective area outputs the H level. It should be noted that the determination value as to whether or not it is a defect region can be determined by taking into account the gain setting amount that is variable in each unit for generating the full addition signal and the difference signal, and the output offset amount that can be generated, The data may be given from the CPU 7, or the defect area detection gate signal generation unit 502 may have a fixed value in advance.

  Here, at the switching point between the reproduction of the defect area and the reproduction of the non-defect area, the reflectivity of the optical disc 1 varies depending on the defect state, so that there is a possibility that the push-pull signal PP varies sharply. Therefore, the defect area / non-defect area switching point detector 503 receives the defect area gate signal GT5 and detects the rising edge thereof. For example, as shown in FIG. 10, the defect area / non-defect area switching point detection signal is detected. As SW5, an H level is output, and a signal which becomes an L level after a lapse of a predetermined time T when a steep fluctuation is stabilized in the push-pull signal PP is generated. Note that the predetermined time T can be assumed in the defect area reproduction operation and the non-defect area reproduction operation. The gain setting amount that can be changed in each part, the output offset amount that can be generated in each part, and the response characteristics when the gain is switched in each part In addition, when gain switching is not performed in each part, such as when the defect area is small, it can be determined by considering the response characteristics of each part. Then, this value may be given from the CPU 7, or the defect area / non-defect area switching point detector 503 may have a fixed value in advance.

  On the other hand, the push-pull signal PP is input to the wobble peak detection unit 9 and a wobble peak detection signal WPK is output. When the defect area / non-defect area switching point detection signal SW5 is at L level with respect to the wobble peak detection signal WPK, only the first offset OFS1 from the first offset generator 10 is applied, and the defect area / When the non-defect region switching point detection signal SW5 is at the H level, the second offset OFS2 from the second offset generator 103 is applied in addition to the first offset OFS1, and the slice reference signal LTH5 is generated.

  Thereafter, when the push-pull signal PP is sliced with the slice reference signal LTH5 by the comparator 13, when the push-pull signal PP is not sharply changed and the defect region / non-defect region switching point detection signal SW5 is at the L level, Since the potential of the slice reference signal LTH5 is lower than the land pre-pit signal component included in the push-pull signal PP and larger than the wobble signal component and noise component included in the push-pull signal PP, it corresponds to the land pre-pit signal component. Thus, an H level signal can be output as the land pre-pit signal LPP. On the other hand, when the push-pull signal PP has a steep fluctuation and the defect area / non-defect area switching point detection signal SW5 becomes H level, the potential of the slice reference signal LTH5 becomes higher than the push-pull signal PP. The wobble signal component and noise component included in the push-pull signal PP are not erroneously detected as the land pre-pit signal LPP.

  The response speed of generation of the defect area gate signal GT5 by the defect area detection gate signal generation unit 502 is slow, and the rising position of the defect area / non-defect area switching point detection signal SW5 is higher than the sharp fluctuation position of the push-pull signal PP. In the case of delay, for example, as shown in the first embodiment, the delay unit 101 is provided in the preceding stage of the wobble peak detection unit 9 and the comparator 13, and the wobble detection operation is performed using the delayed push-pull signal. Then, the generation operation of the slice reference signal LTH5 and the generation operation of the land pre-pit signal LPP may be performed.

  In the fifth embodiment of the present invention, erroneous detection of the land pre-pit signal LPP can be avoided even if the push-pull signal PP has a sharp fluctuation at the switching point between reproduction of the defect area and reproduction of the non-defect area. it can.

  In addition, the defect area gate signal GT5 is used in FIG. 9 as an information recording / reproducing apparatus, such as servo control for causing the laser spot from the optical pickup 2 to follow the track of the optical disk 1 for holding in the defect area. The defect region detection gate signal generation unit 502 does not need to be newly provided to realize the present embodiment and is also used in other components not shown, and the push-pull provided in the first embodiment. Since the defect area / non-defect area switching point detector 503 having a simpler configuration than the signal fluctuation detector 102 is used, when the information recording / reproducing apparatus according to Embodiment 5 of the present invention is configured by an electric circuit, the circuit area And power consumption can be reduced.

Embodiment 6
Embodiment 6 of the present invention will be described below with reference to the drawings. FIG. 11 is a block diagram showing an information recording / reproducing apparatus according to Embodiment 6 of the present invention. The difference from the information recording / reproducing apparatus according to Embodiment 1 shown in FIG. An offset amount variable unit 601 for changing the second offset OFS2 is further provided. The offset amount variable unit 601 receives the variation information of the push-pull signal PP detected by the push-pull signal variation detection unit 102, varies the offset amount according to the variation information, and outputs the variable offset signal VOFS2. The second offset generating unit 103 is configured to output the variable offset signal VOFS2 as the second offset OFS2 only when the fluctuation detection signal SW1 is at the H level, as in the first embodiment.

  FIGS. 12A and 12B show the land pre-pit detection operation when the push-pull signal PP has a steep fluctuation according to the first and sixth embodiments of the present invention. 11 shows the waveform of each part having a reference numeral 11, and the amount of fluctuation is smaller than that of the push-pull signal PP shown in FIG. 2, and the land pre-pit signal component is at a position close to the fluctuation part of the push-pull signal PP. In some cases.

  Here, FIG. 12A shows a case where the slice reference signal LTH1 is generated by applying the second offset OFS2 as a predetermined fixed value regardless of the fluctuation amount of the push-pull signal PP as described in the first embodiment. A part of the land pre-pit signal component at a position close to the fluctuation part of the delayed push-pull signal PPd is not detected (the land pre-pattern described in FIG. 12A). (Refer to the dotted line portion of the pit signal LPP). On the other hand, FIG. 12B shows the waveforms of the respective parts according to the sixth embodiment. The second offset OFS2 applied when the fluctuation detection signal SW1 is at the H level is a variable that changes according to the fluctuation amount of the push-pull signal PP. Since the land pre-pit signal LPP is detected based on the slice reference signal VTH6 generated by applying the offset signal VOFS2 to the wobble peak detection signal WPK, the delayed push that has not been detected in FIG. The land pre-pit signal component at a position close to the fluctuation portion of the pull signal PPd can be detected normally.

  In the sixth embodiment of the present invention, push-pull such as a switching point between a reproduction operation and a recording operation, a switching point between reproduction of an unrecorded area and reproduction of a recorded area, or a switching point from a defect area to a non-defect area, etc. In addition to avoiding erroneous detection of the land pre-pit signal LPP even if the signal PP has a steep fluctuation, the second offset OFS2 is made variable according to the fluctuation amount of the push-pull signal PP. The land pre-pit detection operation after the fluctuation of the push-pull signal PP has converged can be quickly restored.

<< Embodiment 7 >>
Hereinafter, Embodiment 7 of the present invention will be described with reference to the drawings. FIG. 13 is a block diagram showing an information recording / reproducing apparatus according to Embodiment 7 of the present invention. The difference from the information recording / reproducing apparatus according to Embodiment 4 shown in FIG. An offset amount variable unit 701 for changing the second offset OFS2 is further provided. The offset amount variable unit 701 receives laser power fluctuation information from the laser power control unit 8, varies the offset amount according to the laser power fluctuation information, and outputs a variable offset signal VOFS 2. Similarly to the fourth embodiment, the second offset generation unit 103 is configured to output the variable offset signal VOFS2 as the second offset OFS2 only when the laser power switching point detection signal SW4 is at the H level.

  FIGS. 14A and 14B show the land pre-pit detection operation when the push-pull signal PP has a steep fluctuation at the laser power switching point according to the fourth and seventh embodiments of the present invention. 7 and 13 show the waveforms of the respective parts denoted by the reference numerals in FIG. 7 and FIG. 13, and the fluctuation amount is smaller than that of the push-pull signal PP shown in FIG. This is a case where there is a land pre-pit signal component.

  Here, FIG. 14A shows each part when the slice reference signal LTH4 is generated by applying the second offset OFS2 as a predetermined fixed value regardless of the fluctuation amount of the laser power as described in the fourth embodiment. A part of the land pre-pit signal component at a position close to the fluctuation part of the push-pull signal PP is not detected (the dotted line of the land pre-pit signal LPP described in FIG. 14A). See section). On the other hand, FIG. 14B shows the waveform of each part according to the seventh embodiment. The second offset OFS2 applied when the laser power switching point detection signal SW4 is at the H level changes according to the amount of fluctuation of the laser power. The variable offset signal VOFS2 is applied. As the variable offset signal VOFS2, for example, as shown in FIG. 14B, after the initial potential Vs is generated, the potential is gradually lowered. To do. Note that the initial potential Vs and the rate at which the potential is lowered are the gain setting amount that can be changed in each unit, the output offset amount that can be generated in each unit, and the push-pull signal that is generated due to laser power variation. The fluctuation of PP may be determined in consideration of the response characteristics of each part related to the time for convergence to the normal level. Since the land pre-pit signal LPP is detected based on the slice reference signal VTH7 generated by applying the generated variable offset signal VOFS2 to the wobble peak detection signal WPK in this way, it is not detected in FIG. The land pre-pit signal component at a position close to the fluctuation portion of the push-pull signal PP that has been detected can be normally detected.

  In the seventh embodiment of the present invention, the push-pull signal PP can be avoided in addition to avoiding erroneous detection of the land pre-pit signal LPP even if the push-pull signal PP has a sharp fluctuation at the laser power switching point. Since the second offset OFS2 is made variable in accordance with the fluctuation amount, the land pre-pit detection operation after the fluctuation of the push-pull signal PP has converged can be returned quickly.

Embodiment 8
Embodiment 8 of the present invention will be described below with reference to the drawings. 15 is a block diagram showing an information recording / reproducing apparatus according to Embodiment 8 of the present invention. The difference from the information recording / reproducing apparatus according to Embodiment 1 shown in FIG. A droop amount control unit 801 is further provided for varying the droop amount of the peak value detection operation of the wobble signal component of the push-pull signal PPd. The droop amount control unit 801 receives the fluctuation detection signal SW1 from the push-pull signal fluctuation detection unit 102, detects its falling position, increases the droop amount by a predetermined time DPT, and increases the droop follow-up speed. Thus, the wobble peak detection unit 9 is controlled. Note that the predetermined time DPT for changing the droop amount is a gain setting amount in which the time until the push-pull signal PP converges from the maximum peak value at which the push-pull signal PP fluctuates to the amplitude of the normal level is variable, and the output that can be generated. It may be determined in consideration of the offset amount, and the droop amount control unit 801 may wait as a fixed value, or may be the time until the wobble peak detection unit 9 detects the peak value of the next wobble signal component.

  16 (a) and 16 (b) show that the push-pull signal PP has a steep fluctuation and is close to the fluctuation part of the push-pull signal PP according to the first and eighth embodiments of the present invention. FIG. 16 shows the waveforms of the respective parts denoted by reference numerals in FIGS. 1 and 15 regarding the land pre-pit detection operation when there is a land pre-pit signal component.

  Here, FIG. 16A is the one according to the first embodiment, and the droop operation of the wobble peak detection signal WPK (the portion that is descending to the right in the wobble peak detection signal WPK) is always at a fixed slope and the potential is constant. When the land pre-pit detection is performed using the slice reference signal LTH1 generated based on the characteristic, the land pre-position located at the portion where the fluctuation of the delayed push-pull signal PPd converges. A part of the pit signal component is not detected (see the dotted line portion of the land pre-pit signal LPP described in FIG. 16A). On the other hand, FIG. 16B shows the waveform of each part according to the eighth embodiment, and the droop follow-up speed of the wobble peak detection signal WPK8 is increased by a predetermined time DPT from the fall of the fluctuation detection signal SW1. Since the slope of the period indicated by DPT also becomes steeper than usual in the slice reference signal VTH8 generated based on the above, if land pre-pit detection is performed using this slice reference signal VTH8, FIG. The land pre-pit signal component located in the portion where the fluctuation of the push-pull signal PPd after delay which has not been detected converges can be normally detected.

  In the eighth embodiment of the present invention, a push-pull such as a switching point between a reproduction operation and a recording operation, a switching point between reproduction of an unrecorded area and reproduction of a recorded area, or a switching point from a defect area to a non-defect area. Even if the signal PP has a steep fluctuation, erroneous detection of the land pre-pit signal LPP can be avoided. In addition, since the droop amount of the peak value detection operation of the wobble signal component is increased by the predetermined time DPT after the fluctuation of the push-pull signal PP is converged, the droop follow-up speed is increased, so that the fluctuation of the push-pull signal PP converges. The land pre-pit detection operation from can be quickly restored.

  Although the above shows an example in which the droop follow-up speed is varied based on the information recording / reproducing apparatus described in the first embodiment, this also applies to the information recording / reproducing apparatus described in the second to seventh embodiments. Can be used. As a configuration thereof, a droop amount control unit 801 is provided in front of the wobble peak detection unit 9 provided in each embodiment, and a signal for triggering an increase in the droop amount is a reproduction operation / recording operation, respectively. Switching point detection signal SW2, recorded / unrecorded area switching point detection signal SW3, laser power switching point detection signal SW4, defect area / non-defect area switching point detection signal SW5 are used for a predetermined time DPT from the falling position. The droop tracking speed of the wobble peak detection signal WPK may be increased. Thereby, also in the second to seventh embodiments, the land pre-pit detection operation after the fluctuation of the push-pull signal PP has converged can be quickly returned, and in particular, the second offset OFS2 is configured to be variable. In the sixth embodiment and the seventh embodiment, the effect of shortening the time to return to the land pre-pit detection operation is great.

Embodiment 9
Embodiment 9 of the present invention will be described below with reference to the drawings. FIG. 17 is a block diagram showing an information recording / reproducing apparatus according to Embodiment 9 of the present invention. The difference from the information recording / reproducing apparatus according to Embodiment 8 shown in FIG. 15 is that a tracking error generator 901, tracking error The fluctuation detecting unit 902 is provided.

  18 (a) and 18 (b) show a change in the push-pull signal PP due to the switching from the seek operation to the reproduction operation according to the first and ninth embodiments of the present invention. FIG. 18 shows the waveforms of the respective parts denoted by reference numerals in FIGS. 1 and 17 regarding the land pre-pit detection operation in the case where there is a land pre-pit signal component at a position immediately after the operation.

  The tracking error generation unit 901 receives, for example, an IV converted signal from the light receiving element 4, and receives a tracking error signal TE for performing servo control for causing the laser spot from the optical pickup 2 to follow the track of the optical disc 1. Generated. The tracking error fluctuation detection unit 902 detects the fluctuation of the tracking error signal TE. For example, as shown in FIG. 18B, when the track following state by servo control is not stable, such as during a seek operation. A tracking error fluctuation state signal TG is output, which becomes L level, shifts to the reproduction operation after performing track pull-in, and becomes H level when the track following state is stabilized. The droop amount control unit 801 receives the tracking error fluctuation state signal TG and the fluctuation detection signal SW1 from the push-pull signal fluctuation detection unit 102, and detects whether the tracking error fluctuation state signal TG rises or changes. After detecting the earlier of the falling positions of the signal SW1, the wobble peak detector 9 is controlled so that the droop amount is increased by the predetermined time DPT and the droop follow-up speed is increased. The predetermined time DPT for changing the droop amount is a gain setting for varying the time from the maximum peak value that can be taken by the push-pull signal PP during the seek operation to the convergence to the normal level amplitude during the reproduction operation. The droop amount control unit 801 may wait as a fixed value by taking into account the amount and the output offset amount that can be generated, or the wobble peak detection unit 9 detects the peak value of the next wobble signal component It may be the time until. In addition, when the tracking error fluctuation state signal TG is at the L level, the droop amount change start position described above does not use the falling position of the fluctuation detection signal SW1, and the tracking error fluctuation state signal TG The rising position may be used.

  Here, FIG. 18A is the one according to the first embodiment, and the droop operation of the wobble peak detection signal WPK (the portion that is descending to the right in the wobble peak detection signal WPK) is always at a fixed slope and the potential is constant. When the land pre-pit detection is performed by using the slice reference signal LTH1 generated based on the characteristic, the shift is made from the seek operation to the reproduction operation, and the wobble peak detection unit 9 performs the delay after the delay. The land pre-pit signal component located in the portion where the fluctuation of the push-pull signal PPd has converged is not detected (see the dotted line portion of the land pre-pit signal LPP described in FIG. 18A). In FIG. 18A, the tracking error signal TE and the tracking error fluctuation state signal TG that do not exist in FIG. 1 are drawn for reference.

  On the other hand, FIG. 18B shows the waveforms of the respective parts according to the ninth embodiment, and uses the rising position of the tracking error fluctuation state signal TG that is earlier than the falling position of the fluctuation detection signal SW1 for a predetermined time DPT. The droop tracking speed of the wobble peak detection signal WPK9 is increased. Accordingly, the slice reference signal VTH9 generated based on this wobble peak detection signal WPK9 also has a steeper slope than the normal period indicated by DPT, and therefore, the land prepit detection is performed using this slice reference signal VTH9. Then, the land pre-pit signal component immediately after the transition from the seek operation which has not been detected in FIG. 18A to the reproduction operation can be normally detected.

  In the ninth embodiment of the present invention, push-pull such as a switching point between a reproduction operation and a recording operation, a switching point between reproduction of an unrecorded area and reproduction of a recorded area, or a switching point from a defect area to a non-defect area, etc. Even if the signal PP has a steep fluctuation, erroneous detection of the land pre-pit signal LPP can be avoided. Further, since the droop amount of the peak value detection operation of the wobble signal component is increased by the predetermined time DPT after the fluctuation of the push-pull signal PP due to the seek operation is converged, the droop follow-up speed is increased. The pit detection operation can be returned quickly.

  Although the above shows an example in which the droop follow-up speed immediately after the seek operation is changed based on the information recording / reproducing apparatus described in the eighth embodiment, this is the information recording described in the first to seventh embodiments. It can also be used in a playback device. As its configuration, a droop amount control unit 801 is provided in front of the wobble peak detection unit 9 provided in each embodiment, and a tracking error variation detection unit 902 that detects a variation in the tracking error signal TE is further provided. The tracking error variation state signal TG from the detection unit 902 is input to the droop amount control unit 801, and the droop tracking speed of the wobble peak detection signal WPK is increased by a predetermined time DPT from the rising position of the tracking error variation state signal TG. What should I do? Thereby, also in Embodiment 1 to Embodiment 7, the land pre-pit detection operation immediately after the seek operation can be quickly returned.

  Further, when the information recording / reproducing apparatus according to each of the above embodiments is configured by an electric circuit, in order to avoid a steep fluctuation that occurs in the push-pull signal PP, an amplifier element that generates the push-pull signal PP is finely divided. Since it is not necessary to make a variable gain setting variable at high speed, the circuit area and power consumption can be reduced.

  In the information recording / reproducing apparatus according to each of the above embodiments, the first offset generation unit 10 and the second offset generation unit 103 are configured as one offset generation unit that can change the offset amount, so that push-pull is performed. When there is no steep fluctuation in the signal PP, a fixed amount of offset potential can be output so that the land reference potential can be detected as a land pre-pit signal, and the push-pull signal PP has a steep fluctuation. Alternatively, an offset potential may be output so that the slice reference potential is higher than the peak level of the push-pull signal PP.

<< Embodiment 10 >>
Embodiment 10 of the present invention will be described below with reference to the drawings. FIG. 19 shows a block diagram related to recording clock generation of the information recording / reproducing apparatus according to the tenth embodiment of the present invention. The information recording / reproducing apparatus is an example using the information recording / reproducing apparatus according to the second embodiment.

  In FIG. 19, the push-pull signal PP is input to the wobble extraction unit 1002, and the wobble signal WBPF is extracted. The wobble extraction unit 1002 is composed of, for example, a band pass filter, and includes a high frequency component including a land pre-pit component included in the push-pull signal PP, a recording pulse residual component during a recording operation, and an RF residual component during a reproducing operation, and servo control. Then, the low frequency component consisting of the DC offset component that could not be removed is removed. The wobble signal WBPF is input to the wobble PLL unit 1003 and generates a recording clock.

  The land pre-pit signal LPP is input to the LPP decoding unit 1001, acquires LPP address information, and transmits it to the CPU 7. The CPU 7 generates information for performing PLL correction control such as gain setting of the wobble PLL unit 1003 and PLL hold according to the LPP address information and the driving state such as the reproduction operation or the recording operation, and transmits the information to the PLL correction control unit 1004 To do. A land pre-pit signal LPP is further input to the PLL correction control unit 1004 to control the wobble PLL unit 1003.

  Here, due to the effect that the pre-pits of the optical disc 1 are recorded in the land portion, the wobble adjacent to the land pre-pits receives interference from the land pre-pits and appears as a jitter component in the wobble signal WBPF. This influence is close to the frequency component of the wobble signal WBPF and is difficult to remove by the wobble extraction unit 1002. The wobble PLL unit 1003 receives the wobble signal WBPF that has received the interference of the land prepits, and this jitter component is recorded. It will appear as clock jitter.

  Therefore, correction control is performed to lower the gain of the wobble PLL unit 1003 at a place where the land pre-pit signal LPP exists from the PLL correction control unit 1004, and recording is performed even when the wobble signal WBPF having a jitter component is input as described above. The influence on the clock can be reduced. The gain adjustment of the wobble PLL unit 1003 may be controlled to be appropriate according to the operation state of the apparatus using the PLL correction control information from the CPU 7. Note that in the place where the land pre-pit signal LPP exists, even when correction control for holding the operation of the wobble PLL unit 1003 is performed, even when a wobble signal WBPF having a jitter component is input, the influence on the recording clock can be reduced. it can.

  However, in order to reduce the influence of the land prepit interference jitter on the recording clock as described above, it is assumed that the land prepit signal LPP is not erroneously detected. That is, when the gain of the wobble PLL unit 1003 is adjusted using the erroneously detected land pre-pit signal LPP, an accurate linear velocity obtained from the wobble signal WBPF obtained from the optical disc 1 cannot be obtained. Particularly in the case where the laser power increases from the reproduction operation to the recording operation, the recording start point is a location where the land pre-pit signal LPP exists, and the land pre-pit signal LPP immediately after the start of recording is erroneously detected. If this occurs, the correction control of the wobble PLL unit 1003 immediately after the start of recording malfunctions, and there is a possibility that the frequency and phase of the recording clock will shift.

  Accordingly, in the tenth embodiment of the present invention, erroneous detection of the land pre-pit signal LPP is prevented at the switching point of the apparatus operation state immediately after recording or the like. Since the influence can be reduced, the reproduction clock generated from the reproduction RF signal during the reproduction operation and the recording clock generated from the wobble during the recording operation can be matched in frequency and phase. In addition, additional recording data can be accurately written with respect to recording data before being added by additional recording or the like. And, by this precise writing, the read clock obtained from the previous recorded data and the read clock obtained when playing the additional recorded part are connected like a single stroke, improving readability during playback. Can be made.

  As the information recording / reproducing apparatus used in the above configuration, any one described in the first to ninth embodiments can be used.

  FIG. 20 is a block diagram showing the seek operation control of the information recording / reproducing apparatus according to the tenth embodiment of the present invention. The information recording / reproducing apparatus is an example using the information recording / reproducing apparatus according to the ninth embodiment.

  In FIG. 20, the servo control unit 1005 receives the tracking error signal TE from the tracking error generation unit 901, and performs tracking servo operation control and seek operation control. This operation control is realized by bidirectionally communicating servo control information between the servo control unit 1005 and the CPU 7.

  Similarly to the information recording / reproducing apparatus shown in FIG. 19, the land pre-pit signal LPP is input to the LPP decoding unit 1001, acquires LPP address information, and is transmitted to the CPU 7.

  Here, seek operation control will be described. The seek operation is performed by notification of a seek operation instruction from the CPU 7 to the servo control unit 1005. When the seek operation is completed, the servo control unit 1005 notifies the completion to the CPU 7, and the CPU 7 confirms the LPP address information obtained from the LPP decoding unit 1001 and immediately determines whether or not the seek operation target address has been reached. When the target address is confirmed, the servo control unit 1005 is notified that the seek operation is completed. If the target address has not been reached, a seek operation instruction from the current address to the target address is servo controlled. Section 1005 is notified again.

  In the seek operation control described above, since the CPU 7 uses the LPP address information using the land pre-pit signal LPP, which is prevented from being erroneously detected, as the determination to reach the target address, it can be used for the determination as accurate address information.

  However, if an information recording / reproducing apparatus having a possibility of erroneous detection is used at the switching point of the push-pull signal PP state or the apparatus operation state, the LPP address information is also incorrect, and therefore, the LPP address information is continuously updated. The CPU 7 requires processing such as monitoring of the characteristics, and cannot be used by the CPU 7 until accurate LPP address information is obtained, and as a result, the CPU 7 determines that a stable land pre-pit signal LPP is obtained without fear of erroneous detection. Cannot instruct seek operation until possible. Alternatively, the seek operation is repeated based on incorrect LPP address information.

  Therefore, in the tenth embodiment of the present invention, since the erroneous detection of the land pre-pit signal LPP is prevented at the switching point of the state of the push-pull signal PP or the device operation state, it is possible to speed up the seek operation control.

  As the information recording / reproducing apparatus used in the above configuration, any one described in the first to ninth embodiments can be used.

  Thus, the many features and advantages of the present invention are apparent from the written description, and thus, it is intended by the appended claims to cover all such features and advantages of the present invention. The Further, since many changes and modifications can be readily made by those skilled in the art, the present invention should not be limited to the exact configuration and operation as illustrated or described. Accordingly, all suitable modifications and equivalents are intended to be within the scope of the present invention.

  The present invention relates to an optical disc having address information by land pre-pits such as DVD-R / RW, which has an effect of preventing deterioration in seek operation and reproduction performance even when the push-pull signal has steep fluctuations such as amplitude and offset. It can be used for a recording / reproducing apparatus.

DESCRIPTION OF SYMBOLS 1 Optical disk 2 Optical pick-up 3 Laser diode 4 Light receiving element 5a, 5b Addition amplifier 6 Subtraction amplifier 7 CPU
8 Laser power control unit 9 Wobble peak detection unit 10 First offset generation unit 11, 12 Adder 13 Comparator 101 Delay unit 102 Push-pull signal fluctuation detection unit 103 Second offset generation unit 202 Recording section gate signal generation unit 203 Reproduction operation / Recording operation switching point detection unit 302 Recorded region detection gate signal generation unit 303 Recorded region / unrecorded region switching point detection unit 403 Laser power switching point detection unit 502 Defect region detection gate signal generation unit 503 Defect region / non-defect region Switching point detectors 601 and 701 Offset variable unit 801 Droop amount controller 901 Tracking error generator 902 Tracking error fluctuation detector 1001 LPP decoder 1002 Wobble extractor 1003 Wobble PLL unit 100 4 PLL correction controller 1005 Servo controller

Claims (10)

A track on which information is recorded is formed by meandering grooves, and a laser beam is applied to an information recording medium in which address information is recorded by prepits on the land between the grooves, and the wobble signal component and the land are reflected from the reflected light. A method of generating a push-pull signal including a pre-pit signal component and detecting the land pre-pit from the push-pull signal,
A wobble peak detection step for performing peak detection of a wobble signal component included in the push-pull signal;
An offset generation step of variably generating an offset signal potential for addition to the wobble peak detection signal;
Adding the wobble peak detection signal and the variable offset signal to generate a slice signal as a comparison reference for land pre-pit detection;
A land pre-pit generation step of comparing the push-pull signal and the slice signal and outputting the comparison result as the land pre-pit signal;
A land pre-pit detection method, wherein the slice signal potential is varied by changing the potential of the offset signal in accordance with a switching point of the push-pull signal state or the device operation state. A track on which information is recorded is formed by meandering grooves, and a laser beam is applied to an information recording medium in which address information is recorded by prepits on the land between the grooves, and the wobble signal component and the land are reflected from the reflected light. An information recording / reproducing apparatus that generates a push-pull signal including a pre-pit signal component and detects the land pre-pit from the push-pull signal,
Wobble peak detection means for performing peak detection of a wobble signal component included in the push-pull signal;
Offset generating means for variably generating an offset signal potential for addition to the wobble peak detection signal;
Means for adding the wobble peak detection signal and the variable offset signal to generate a slice signal as a comparison reference for land pre-pit detection;
Land pre-pit generation means for comparing the push-pull signal and the slice signal and outputting the comparison result as the land pre-pit signal,
An information recording / reproducing apparatus, wherein the slice signal potential is varied by changing the potential of the offset signal in accordance with a switching point of the push-pull signal state or the device operation state. The information recording / reproducing apparatus according to claim 2,
As a means for detecting the state of the push-pull signal, comprising a push-pull signal fluctuation detecting means for detecting a steep fluctuation of the amplitude or DC component of the push-pull signal,
As an offset generation means for variably generating the offset signal potential,
First offset generating means for generating a first offset signal for constantly adding to the wobble peak detection signal;
A second offset generating means for generating a second offset signal when a steep fluctuation is detected in the push-pull signal;
The second offset signal is generated so that the potential of the slice signal is higher than a peak level of the push-pull signal when the push-pull signal is suddenly changed. Information recording / reproducing apparatus. The information recording / reproducing apparatus according to claim 2,
As means for detecting the switching point of the device operating state, comprising means for detecting a switching point between the recording operation and the reproduction operation,
As an offset generation means for variably generating the offset signal potential,
First offset generating means for generating a first offset signal for constantly adding to the wobble peak detection signal;
A second offset generating means for generating a second offset signal when a switching point between the recording operation and the reproducing operation is detected;
The information recording is characterized in that the second offset signal is generated so that the potential of the slice signal becomes higher than the peak level of the push-pull signal at the switching point between the recording operation and the reproducing operation. Playback device. The information recording / reproducing apparatus according to claim 2,
As means for detecting the switching point of the device operating state, comprising means for detecting a switching point between a reproduction operation of a recorded area and a reproduction operation of an unrecorded area,
As an offset generation means for variably generating the offset signal potential,
First offset generating means for generating a first offset signal for constantly adding to the wobble peak detection signal;
A second offset generating means for generating a second offset signal when a switching point between the reproducing operation of the recorded area and the reproducing operation of the unrecorded area is detected;
The second offset signal is generated so that the potential of the slice signal is higher than the peak level of the push-pull signal at the switching point between the reproduction operation of the recorded area and the reproduction operation of the unrecorded area. An information recording / reproducing apparatus. The information recording / reproducing apparatus according to claim 2,
As means for detecting the switching point of the apparatus operating state, comprising means for detecting a switching point of laser power,
As an offset generation means for variably generating the offset signal potential,
First offset generating means for generating a first offset signal for constantly adding to the wobble peak detection signal;
A second offset generating means for generating a second offset signal when the laser power switching point is detected;
The information recording / reproducing apparatus, wherein the second offset signal is generated so that the potential of the slice signal is higher than the peak level of the push-pull signal at the switching point of the laser power. The information recording / reproducing apparatus according to claim 2,
As means for detecting the switching point of the device operating state, comprising means for detecting a switching point between the reproduction operation of the defect area and the reproduction operation of the non-defect area,
As an offset generation means for variably generating the offset signal potential,
First offset generating means for generating a first offset signal for constantly adding to the wobble peak detection signal;
Second offset generation means for generating a second offset signal when a switching point between the reproduction operation of the defect area and the reproduction operation of the non-defect area is detected;
The second offset signal is generated so that the potential of the slice signal is higher than the peak level of the push-pull signal at the switching point between the reproduction operation of the defect area and the reproduction operation of the non-defect area. An information recording / reproducing apparatus. The information recording / reproducing apparatus according to claim 3 or 6,
Means for varying the potential of the second offset signal;
Land pre-pit detection after generation of the second offset signal by varying the potential of the second offset signal in accordance with the fluctuation amount detected by the push-pull signal fluctuation detection means or the fluctuation amount of the laser power. An information recording / reproducing apparatus characterized in that the operation is quickly restored. The information recording / reproducing apparatus according to any one of claims 3 to 8,
The wobble peak detection means has a variable droop amount when performing peak detection of a wobble signal component included in the push-pull signal,
Means for controlling the droop amount of the wobble peak detection means in which the droop amount is variable;
After the generation of the second offset signal, the land pre-pit detection operation is quickly returned by increasing the droop follow-up speed of the wobble peak detection means by the droop amount control means. The information recording / reproducing apparatus according to claim 9.
A means for detecting a change in the tracking error signal;
After the fluctuation amount of the tracking error signal becomes small, the land pre-pit detection operation is quickly returned by increasing the droop tracking speed of the wobble peak detection means by the droop amount control means. apparatus.

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