JP4283203B2 - Land pre-pit amplitude evaluation method and apparatus, and land pre-pit amplitude measurement method and apparatus - Google Patents

Description

  The present invention, for example, evaluates the LPP amplitude in an optical disc such as a DVD-R (DVD-Recordable) or a DVD-RW (DVD-ReRecordable) having a land pre-pit (LPP). TECHNICAL FIELD The present invention relates to the technical field of methods and apparatuses, and the technical field of land prepit amplitude measurement methods and apparatuses for such evaluation methods.

  In a write-once DVD-R and a rewritable DVD-RW, a groove track is wobbling and an LPP is previously formed on a land track between the groove tracks. (See Patent Document 1). By these wobbling and LPP, the rotation speed is controlled, the recording clock is generated, and the recording address is acquired. Here, when detecting the LPP, if the amplitude of the LPP is not an appropriate magnitude, the detection is hindered. Particularly after recording, the amplitude of the LPP decreases due to the influence of the recording signal (recording mark). In view of this, the manufacturer and quality-certified vendors evaluate the amplitude of the LPP as defining a margin for LPP detection after recording in a manufactured DVD-R, DVD-RW, or the like.

  Conventionally, as an LPP amplitude evaluation method for evaluating the amplitude of an LPP after recording, AR (Aperture Ratio after recording) among various evaluation items in the DVD-R standard and the DVD-RW standard defined by the DVD Forum. ) Is measured (see Patent Document 2). For example, the maximum value AP (max) and the minimum value AP (min) of the peak value from the maximum value of the groove track component in the push-pull signal are detected, and the AR value is a standard expression AR = AP (min) / AP ( max) and the evaluation is performed when the AR value is equal to or greater than a specified value. For example, in the case of DVD-R, if AR is 15% or more, the amplitude of LPP is evaluated as being spec-in (within the standard). In this case, the disc to be evaluated is certified as a regular DVD-R on condition that other evaluation items (for example, jitter) are also spec-in. On the other hand, when AR is less than 15%, it is evaluated that it is a spec out (non-standard).

JP 2004-158068 A JP 2003-248933 A

  Generally, the influence of the recording signal, that is, the RF signal mark portion can be considered as a cause of the decrease in the LPP amplitude after recording. In the conventional AR measurement described above, the LPP amplitude is measured in all cases where the RF signal mark portion and the RF signal space portion are adjacent to the LPP. Therefore, it is impossible to evaluate only the amplitude level of the LPP signal in the RF signal space portion (that is, the space portion corresponding to the recording space between the mark portions corresponding to the recording pits on the RF signal). For example, in the case of detecting the LPP after recording and generating a recording clock for additional recording, it is sufficient that only the LPP existing in the RF signal space portion can be detected and used, but in this case, that is, the RF signal space. Even with DVD-R and DVD-RW that are sufficient as the amplitude of the LPP of the part, there is a possibility that the evaluation using the conventional AR measurement described above will be out of specification. As described above, there is a technical problem that the necessity and validity of performing the evaluation of the amplitude of the LPP by the above-described conventional AR measurement are not necessarily high.

  The present invention has been made in view of the above-mentioned problems, for example, and makes it possible to more accurately determine the degree of signal detection with respect to the LPP in the RF signal space portion or in the RF signal mark portion. It is an object of the present invention to provide a method and apparatus, and a land pre-pit amplitude measuring method and apparatus for such an evaluation method.

  The land pre-pit amplitude evaluation method according to claim 1, wherein the land pre-pit amplitude evaluation method has land pre-pits formed in advance on the land track, and marks and spaces are alternately recorded on the groove track. A land pre-pit amplitude evaluation method for evaluating the amplitude of an LPP signal based on the land pre-pits, wherein an irradiation step of irradiating the optical disk with reading light and receiving reflected light from the optical disk based on the reading light A light receiving step, a push-pull signal generating step for generating a push-pull signal based on the received reflected light, an RF signal generating step for generating an RF signal based on the received reflected light, An RF binarized signal generating step for generating an RF binarized signal by binarizing the RF signal, and the generated RF2 A specific mark or space portion detecting step for detecting an RF binary signal mark or space portion corresponding to a specific mark or space having a predetermined length among the mark and space, and the detected signal on the time axis. A specific mark or in-space LPP signal detection step of detecting the LPP signal existing in the RF binarized signal mark or space as a specific mark or in-space LPP signal, and the detected specific mark or in-space LPP signal An LPP waveform acquisition step of acquiring a waveform n times (where n is a natural number of 2 or more), and a ratio of a minimum value to a maximum value of the amplitude of the waveform acquired n times exceeds a predetermined threshold value or A determination step of determining whether or not the predetermined threshold is reached.

  The land pre-pit amplitude measuring method according to claim 10, wherein the land pre-pit amplitude measuring method has a land pre-pit formed in advance on a land track, and marks and spaces are recorded alternately on the groove track. A land pre-pit amplitude measuring method for measuring an amplitude of an LPP signal based on the land pre-pits, wherein an irradiation step of irradiating the optical disk with reading light and receiving reflected light from the optical disk based on the reading light A light receiving step, a push-pull signal generating step for generating a push-pull signal based on the received reflected light, an RF signal generating step for generating an RF signal based on the received reflected light, An RF binarized signal generating step for generating an RF binarized signal by binarizing the RF signal, and the generated RF A specific mark or space portion detection step for detecting an RF binary signal mark or space portion corresponding to a specific mark or space having a predetermined length among the mark and space on the value signal, and the detection on the time axis A specific mark or in-space LPP signal detecting step of detecting the LPP signal existing in the RF binarized signal mark or space portion as a specific mark or in-space LPP signal, and the detected specific mark or in-space LPP signal And an LPP waveform acquisition step for acquiring the waveform.

  12. The land pre-pit amplitude evaluation apparatus according to claim 11, wherein the land pre-pit amplitude evaluation apparatus has land pre-pits formed in advance on a land track, and marks and spaces are recorded alternately on the groove track. The land pre-pit amplitude evaluation apparatus for evaluating the amplitude of the LPP signal based on the land pre-pits, the irradiation means for irradiating the optical disk with reading light, and the reflected light from the optical disk based on the reading light received A light receiving means for generating a push-pull signal based on the received reflected light, an RF signal generating means for generating an RF signal based on the received reflected light, RF binarized signal generating means for generating an RF binarized signal by binarizing the RF signal, and the generated RF A specific mark or space portion detecting means for detecting an RF binary signal mark or space portion corresponding to a specific mark or space having a predetermined length among the mark and space on the value signal, and the detection on the time axis Specific mark or in-space LPP signal detection means for detecting the LPP signal existing in the RF binarized signal mark or space portion as a specific mark or in-space LPP signal, and the detected specific mark or in-space LPP signal LPP waveform acquisition means for acquiring the waveform of n times (where n is a natural number equal to or greater than 2), and the ratio of the minimum value to the maximum value of the amplitude of the waveform acquired n times exceeds a predetermined threshold value. Or a determination means for determining whether or not the predetermined threshold value is reached.

  The land pre-pit amplitude measuring apparatus according to claim 12, wherein the land pre-pit amplitude measuring apparatus has land pre-pits formed in advance on a land track, and marks and spaces are recorded alternately on the groove track. The land pre-pit amplitude measuring device for measuring the amplitude of the LPP signal based on the land pre-pits, comprising: an irradiating means for irradiating the optical disk with reading light; and receiving reflected light from the optical disk based on the reading light A light receiving means for generating a push-pull signal based on the received reflected light, an RF signal generating means for generating an RF signal based on the received reflected light, RF binarized signal generating means for generating an RF binarized signal by binarizing the RF signal, and the generated RF A specific mark or space portion detecting means for detecting an RF binary signal mark or space portion corresponding to a specific mark or space having a predetermined length among the mark and space on the value signal, and the detection on the time axis Specific mark or in-space LPP signal detection means for detecting the LPP signal existing in the RF binarized signal mark or space portion as a specific mark or in-space LPP signal, and the detected specific mark or in-space LPP signal And an LPP waveform acquisition means for acquiring the waveform.

  The operation and other advantages of the present invention will become apparent from the best mode for carrying out the invention described below.

(Embodiment of Land Prepit Amplitude Evaluation Method)
An embodiment of the land pre-pit amplitude evaluation method according to the present invention is the land pre-pit in an optical disc having land pre-pits formed in advance on a land track and in which marks and spaces are recorded alternately on a groove track. A land pre-pit amplitude evaluation method for evaluating the amplitude of an LPP signal based on: an irradiation step of irradiating the optical disc with reading light; a light receiving step of receiving reflected light from the optical disc based on the reading light; A push-pull signal generating step for generating a push-pull signal based on the received reflected light, an RF signal generating step for generating an RF signal based on the received reflected light, and binarizing the RF signal Thus, an RF binarized signal generating step for generating an RF binarized signal, and the generated RF binarized signal, A specific mark or space portion detection step for detecting a specific mark or space portion corresponding to a specific mark or space having a predetermined length, and the detected RF binarization signal on the time axis. The specific mark or in-space LPP signal detection step of detecting the LPP signal existing in the mark or space portion as a specific mark or in-space LPP signal, and the waveform of the detected specific mark or in-space LPP signal is represented by n ( Where n is a natural number of 2 or more) and the ratio of the minimum value to the maximum value of the amplitude exceeds or reaches the predetermined threshold with respect to the waveform acquired n times. A determination step of determining whether or not.

  According to the present embodiment, first, for example, reading light is irradiated to an optical disc such as a DVD-R or DVD-RW by an irradiation process using a semiconductor laser of an optical pickup, for example, and a light receiving element of the optical pickup is used. Reflected light based on the reading light is received by the light receiving step used. Subsequently, based on the reflected light received in this way, a push-pull signal is generated by a push-pull signal generation process, and in parallel with this, an RF signal is generated by an RF signal generation process. The push-pull signal is generated, for example, as a difference in the amount of reflected light received by the first and second light receiving surfaces divided by a dividing line extending in a direction optically corresponding to the tangential direction of the groove track. Further, the RF signal is generated as, for example, the total amount of reflected light received by the light receiving surface divided into four.

  In particular, for example, a specific mark or space of a predetermined length is supported by a specific mark or space portion detection process using a mark detector for detecting a recording mark on the RF binarized signal or a space detector for detecting a recording space. The RF binarized signal mark or space portion is detected. Here, for example, a single type of space portion is detected, such as a 14T space portion, which is an RF binarized space portion having the longest pulse width in the RF signal. Alternatively, for example, a single type of mark portion such as a 14T mark portion, a plurality of types of space portions such as a combination of 14T space and 10T space, and a plurality of types of mark portions such as a combination of 14T mark and 9T mark are detected. However, a combination of a space portion and a mark portion, or a combination of a space portion and a mark portion is excluded from the detection target here.

  Subsequently, it exists on the time axis in the RF binarized signal mark or space portion detected in this way by the LPP signal detection process in a specific space or mark using a comparator, a gate pulse generator, a logic circuit, etc. The LPP signal to be detected is detected as a specific mark or in-space LPP signal.

  Subsequently, the waveform of the specific mark or the LPP signal in the space detected in this way, for example, by an LPP waveform acquisition step using a digital oscilloscope is acquired n times, for example, 100 times, and further, for example, an oscilloscope, a personal computer, The ratio (AR) of the minimum value (AP (min)) to the maximum value (AP (max)) of the amplitude of the waveform acquired n times in this way by the determination step using the It is determined whether it exceeds or reaches the predetermined threshold. Here, the predetermined threshold is a value of a property defined by a standard such as a DVD forum, for example. If the predetermined threshold is exceeded or the predetermined threshold is reached, the LPP signal amplitude may be evaluated as a spec-in. it can. In particular, in the above-described specific mark or space portion detection step, a mixture of a space portion and a mark portion is excluded from the detection target. Therefore, the determination regarding the final ratio (AR) is performed in the RF signal space portion. Therefore, it is possible to carry out with accuracy and stability only with respect to the amplitude level of the LPP signal in the RF mark section or only with respect to the amplitude level of the LPP signal in the RF mark section.

  As a result, according to the present embodiment, only the amplitude level of the LPP signal in the RF signal space portion (that is, the RF binarized signal space portion) or the RF mark portion (that is, the RF binarized signal mark portion) is evaluated. Therefore, it is possible to more accurately determine the detection degree of the signal for the LPP in the RF signal space portion or the RF mark portion.

  In another aspect of the embodiment of the land pre-pit amplitude evaluation method of the present invention, the specific mark or in-space LPP signal detection step is configured to detect the LPP signal at a predetermined slice level from the generated push-pull signal. An LPP binarized signal generating step of generating an LPP binarized signal by performing the binarization, and among the generated LPP binarized signals, the detected RF binarized signal mark or space on the time axis The specific mark or the in-space LPP signal is detected by detecting the LPP signal included in the generated push-pull signal using a signal existing in the section as a trigger signal.

  According to this aspect, in the specific mark or in-space LPP signal detection step, the LPP signal is binarized at a predetermined slice level from the push-pull signal, for example, by the LPP binarization signal generation step using a comparator or the like. An LPP binarized signal is generated. Of the LPP binarized signals generated in this way, an RF binarized signal mark or a signal existing in the space part is used as a trigger signal, and the specific mark or in-space LPP signal is detected. In this aspect, “the LPP binarized signal that is present in the detected RF binarized signal mark or space portion on the time axis as a trigger signal” means, for example, an LPP binarized signal and an RF2 value This means that the period in which the signal signal space part overlaps on the time axis coincides with the sampling period of the push-pull signal. For this reason, for example, a logical product of an LPP binarized signal and a signal indicating an RF binarized signal space portion (for example, a gate pulse indicating a 14T space), or preferably the center in the LPP binarized signal and the RF binarized signal space portion A trigger signal is generated as a logical product of a signal indicating a shift portion (for example, a gate pulse indicating a 10T space closer to the center in the 14T space), and the waveform of the LPP signal included in the push-pull signal is acquired by this trigger signal. The

  In this aspect, the LPP binary signal generation step may be configured to set the slice level at a predetermined ratio with respect to the maximum value of the amplitude of the waveform acquired n times.

  With this configuration, the LPP signal is appropriately binarized at a slice level set to a predetermined ratio such as 20% with respect to the maximum value of the amplitude of the waveform acquired n times by the LPP waveform acquisition step. Can be realized.

  In another aspect of the embodiment of the land pre-pit amplitude evaluation method of the present invention, the LPP waveform acquisition step includes an LPP waveform overlap display step for displaying the waveform acquired n times in an overlapping manner.

  According to this aspect, the waveform acquired n times by the LPP waveform overlap display step using a digital oscilloscope or the like is displayed in duplicate, so that the waveform of the LPP signal in the specific mark or space is visually inspected. It is also possible.

  In this aspect, the LPP waveform overlap display step may be configured to overlap and display the waveform acquired n times on a digital oscilloscope.

  If comprised in this way, n waveforms acquired over the time of several seconds to several tens of seconds or several minutes-several tens of minutes, for example during a LPP waveform duplication display process will be displayed on a digital oscilloscope. Therefore, the ratio (AR) of the minimum value (AP (min)) to the maximum value (AP (max)) of the amplitudes in the n waveforms can be acquired relatively easily and with high accuracy.

  In another aspect of the embodiment of the land pre-pit amplitude evaluation method of the present invention, the specific mark or space portion detection step includes a gate pulse in the detected RF binary signal mark or space portion on the time axis. The specific mark or in-space LPP signal detection step includes detecting the specific mark or in-space LPP signal based on the generated gate pulse.

  According to this aspect, during the specific mark or space portion detection step, the gate pulse generation step generates a gate pulse having a time length of 10T, for example, included in the RF binary signal space portion having a time length of 14T, for example. Is done. Thereafter, based on this gate pulse, the specific mark or the in-space LPP signal is reliably detected.

  In an embodiment according to the land pre-pit amplitude evaluation method of the present invention, in the aspect in which the specific mark or in-space LPP signal detection step includes an LPP binary signal generation step, the LPP waveform acquisition step includes the detection on the time axis. A gate pulse generating step for generating a gate pulse in the generated RF binarized signal mark or space, and among the generated LPP binarized signals, an LPP binarized signal existing in the gate pulse on the time axis A trigger signal generating step for outputting the trigger signal, and the specific mark or in-space LPP signal detecting step detects the specific mark or in-space LPP signal using the output trigger signal. You may comprise.

  With this configuration, during the LPP waveform acquisition step, a gate pulse having a time length of 10T, for example, included in the RF binarized signal space portion having a time length of 14T, for example, is generated by the gate pulse generation step. . Subsequently, among the LPP binarized signals, the LPP binarized signal existing in the gate pulse on the time axis is output as a trigger signal by the trigger signal generation step. The specific mark or the in-space LPP signal is reliably detected by the trigger signal output in this way.

  In another aspect of the embodiment of the land pre-pit amplitude evaluation method of the present invention, the mark or space portion detection step detects an RF binary signal space portion corresponding to a 14T space as the specific mark or space. .

  According to this aspect, it is possible to detect the RF signal space portion corresponding to the 14T space which is the longest space and its existence is guaranteed on the standards such as the DVD-R standard and the DVD-RW standard. It becomes possible.

  In an embodiment according to the land pre-pit amplitude evaluation method of the present invention, in an aspect in which the LPP waveform acquisition step includes an LPP waveform overlap display step, the LPP waveform acquisition step includes the waveform of the detected specific mark or in-space LPP signal. May be included in a waveform acquisition number determination step of counting the number of trigger output pulses of the digital oscilloscope to acquire n times.

  If comprised in this way, since the trigger output pulse number of a digital oscilloscope is counted by the waveform acquisition number determination process, it becomes possible to acquire the waveform of an LPP signal n times comparatively reliably and easily.

(Embodiment of Land Prepit Amplitude Measuring Method)
The embodiment according to the land pre-pit amplitude measurement method of the present invention is similar to the above-described embodiment according to the land pre-pit amplitude evaluation method of the present invention in that the irradiation step, the light receiving step, and the push-pull signal generation step , An RF signal generation step, an RF binarization signal generation step, a specific mark or space portion detection step, and a specific mark or in-space LPP signal detection step, and further within the detected specific mark or space An LPP waveform acquisition step of acquiring an LPP signal waveform.

  According to this embodiment, the irradiation process, the light receiving process, the push-pull signal generation process, the RF signal generation process, the RF binarized signal generation process, the specific mark or space portion detection process, and the specific mark or in-space LPP signal detection process are performed. Then, the waveform of the LPP signal is acquired by the LPP waveform acquisition step. If such waveform acquisition is performed n times and the result is used to evaluate the LPP signal amplitude, the embodiment according to the land pre-pit amplitude evaluation method of the present invention described above can be realized.

  In the present embodiment, various aspects similar to those in the embodiment according to the land pre-pit amplitude evaluation method of the present invention described above can be adopted.

(Embodiment of Land Pre-Pit Amplitude Evaluation Device)
An embodiment of the land pre-pit amplitude evaluation apparatus according to the present invention has the land pre-pit formed in advance on a land track, and the land pre-pit in an optical disc in which marks and spaces are alternately recorded on a groove track. A land pre-pit amplitude evaluation apparatus that evaluates the amplitude of an LPP signal based on the above, an irradiating means for irradiating the optical disk with reading light, a light receiving means for receiving reflected light from the optical disk based on the reading light, and Push-pull signal generating means for generating a push-pull signal based on the received reflected light, RF signal generating means for generating an RF signal based on the received reflected light, and binarizing the RF signal The RF binarized signal generating means for generating the RF binarized signal, and on the generated RF binarized signal, And a specific mark or space part detection means for detecting a specific mark or space part corresponding to a specific mark or space of a predetermined length, and the detected RF binary signal on the time axis The specific mark or in-space LPP signal detecting means for detecting the LPP signal existing in the mark or space portion as a specific mark or in-space LPP signal, and the waveform of the detected specific mark or in-space LPP signal is represented by n ( However, the ratio of the minimum value to the maximum value of the amplitude of the LPP waveform acquisition means that acquires n times a natural number of 2) times and the waveform acquired n times exceeds or reaches the predetermined threshold. Determination means for determining whether or not.

  According to the present embodiment, as in the case of the embodiment according to the land pre-pit amplitude evaluation method of the present invention described above, it is possible to more accurately determine the detection degree of the signal for the LPP in the RF signal space portion. It becomes.

  In the present embodiment, various aspects similar to those in the embodiment according to the land pre-pit amplitude evaluation method of the present invention described above can be adopted.

(Embodiment of Land Pre-Pit Amplitude Measuring Device)
The embodiment of the land pre-pit amplitude measuring device of the present invention is similar to the above-described embodiment of the land pre-pit amplitude measuring device of the present invention in that the irradiating means, the light receiving means, the push-pull signal generating means, , An RF signal generation means, an RF binarized signal generation means, a specific mark or space portion detection means, and a specific mark or in-space LPP signal detection means, and further within the detected specific mark or space LPP waveform acquisition means for acquiring the waveform of the LPP signal.

  According to this embodiment, the irradiation means, the light receiving means, the push-pull signal generating means, the RF signal generating means, the RF binarized signal generating means, the specific mark or space portion detecting means, and the specific mark or in-space LPP signal detecting means Through various processes, the waveform of the LPP signal is acquired by the LPP waveform acquisition means. If such a waveform is acquired n times and the result is used to evaluate the LPP signal amplitude, the embodiment according to the land pre-pit amplitude evaluation apparatus of the present invention described above can be realized.

  In the present embodiment, various aspects similar to those in the embodiment according to the land pre-pit amplitude evaluation method of the present invention described above can be adopted.

  The optical disc according to the various embodiments described above may be a single-layer disc having one recording layer, or a two-layer or multi-layer disc having two or more recording layers. As long as the optical disc is of a type having LPP, the LPP can be an evaluation object by the land pre-pit amplitude evaluation method and apparatus of the present invention.

  As described in detail above, according to the embodiment of the land pre-pit amplitude evaluation method, the RF binarized signal generation step, the specific mark or space portion detection step, the specific mark or in-space LPP signal detection step, the LPP waveform acquisition step In addition, according to the embodiment of the land pre-pit amplitude evaluation apparatus, the RF binarized signal generation means, the specific mark or space portion detection means, the specific mark or in-space LPP signal detection means, LPP Since the waveform acquisition unit and the determination unit are provided, it is possible to more accurately determine the detection degree of the signal with respect to the LPP in the RF signal space portion. Furthermore, according to the embodiment according to the land pre-pit amplitude measurement method, since it includes an RF binarized signal generation step, a specific mark or space portion detection step, a specific mark or in-space LPP signal detection step, and an LPP waveform acquisition step, Further, according to the embodiment relating to the land pre-pit amplitude measuring apparatus, since it includes RF binarized signal generating means, specific mark or space portion detecting means, specific mark or in-space LPP signal detecting means, and LPP waveform acquiring means, The embodiment according to the land pre-pit amplitude evaluation method and apparatus of the present invention described above can be realized.

  The effect | action and other gain of this embodiment are further clarified from the Example demonstrated below.

  Embodiments of the present invention will be described below with reference to the drawings.

  First, with reference to FIG. 1 and FIG. 2, an optical disc having LPP, which is an evaluation target of the LPP amplitude evaluation method according to the present embodiment, will be described. FIG. 1 shows the basic structure of the optical disc according to the present embodiment, the upper portion is a schematic plan view of an optical disc having a plurality of recording areas, and the lower portion associated therewith is in the radial direction. It is a schematic conceptual diagram of a recording area structure. FIG. 2 is a partially enlarged perspective view of the recording surface of the optical disc according to the present embodiment.

  The optical disk according to the present embodiment may be, for example, a write-once optical disk that can be recorded only once by an irreversible change recording method using an organic dye film, or a reversible change recording using a phase change film. It may be a rewritable optical disc that can be recorded many times and reproduced many times depending on the method.

  As shown in FIG. 1, an optical disc 100 has, for example, a lead-in area 101, a data area 102, and a data area 102 on a recording surface on a disc body having a diameter of about 12 cm from the inner peripheral side to the outer peripheral side with the center hole 1 as the center. A lead-out area 103 is provided.

  The lead-in area 101 is provided with a control data zone and the like, for example, various control information for reproduction or recording control, various management information and the like are recorded. In the data area 102, content information such as video information and audio information and various data are recorded. In the lead-in area 101, the data area 102, and the lead-out area 103, for example, a groove track and a land track are provided alternately in a spiral shape or a concentric shape around the center hole 1, and the recording track 10 is provided. Is formed.

  Note that recording data is recorded on the track 10 in units of 1 ECC block (cluster), which is a management unit in which, for example, 16 sectors 11 are collected. This 1 ECC block is a management unit based on preformat address information capable of error correction.

  As shown in FIG. 2, in this embodiment, the optical disc 100 has a recording layer 107 made of a dye film or a phase change film constituting the information recording surface laminated on the lower side of the disc-shaped transparent substrate 106, and further A reflective layer 108 is laminated on the lower side. Groove tracks GT and land tracks LT are alternately formed on the information recording surface formed by the surface of the recording layer 107.

  In FIG. 2, a protective film or a passivation film may be laminated below the reflective layer 108.

  During recording and reproduction of the optical disc 100, for example, as shown in FIG. 2, the laser beam LB is irradiated onto the groove track GT through the transparent substrate 106. For example, at the time of recording, recording is performed on the recording layer 107 according to the recording data by irradiating the laser beam LB with the recording laser power. On the other hand, at the time of reproduction, the recording data recorded on the recording layer 107 is read by irradiating the laser beam LB with a reproduction laser power weaker than the recording laser power.

  A wobble 109 is provided in the groove track GT. That is, the groove track GT is oscillated with a constant amplitude and spatial frequency. The period of the wobble 109 is set to a predetermined value. The preformat address information may be recorded in advance by modulating the wobble 109 by a predetermined modulation method such as frequency modulation or phase modulation.

  The land track LT is provided with an LPP (land pre-pit). For example, when the optical disc 100 is a DVD-R or a DVD-RW, LPP indicates preformat address information.

  With these wobbles 109 and LPP, control of the number of revolutions, generation of a recording clock, acquisition of a recording address, and the like are performed during data writing.

  The present invention is not particularly limited to the optical disc 100 having three recording areas as shown in FIG. For example, the presence of the lead-in area 101 and the lead-out area 103 is also arbitrary, and a data area 102 in which recording data is recorded and a PCA (Power Calibration Area) recording area for detecting optimum recording power (not shown) are provided. It may be done.

  Next, with reference to FIG. 3, an outline of the overall configuration of the LPP amplitude evaluation apparatus according to the present embodiment will be described. FIG. 3 is an overall block diagram of the LPP amplitude evaluation apparatus.

  As shown in FIG. 3, the LPP amplitude evaluation apparatus includes a drive unit 201 and a measurement unit 202. Among these, the drive unit 201 includes an RF and LPP signal generation unit 1, a spindle motor 2, and a drive control unit 3. The measurement unit 202 includes a trigger signal generation unit 4, a waveform measurement / evaluation unit 5, and a measurement control unit 6.

  The RF and LPP signal generation unit 1 includes an optical pickup 1a that irradiates the optical disc 100 with the laser beam LB under the control of the drive control unit 3, receives the reflected light, and outputs a light reception signal. Thus, the push-pull signal Spp and the RF signal Srf are generated. The optical pickup 1a constitutes an example of “irradiation means” and “light receiving means” according to the present invention, and the RF and LPP signal generation unit 1 includes “push-pull signal generation means” and “RF signals” according to the present invention. An example of “generating means” is configured.

  The spindle motor 2 rotates the disk 100 under the control of the drive control unit 3. Preferably, spindle servo based on the clock signal is performed.

  The trigger signal generation unit 4 includes a controller or the like, and generates a trigger signal Str under the control of the measurement control unit 6. Further, the measurement LPP signal Sme is generated from the input push-pull signal Spp. The trigger signal generation unit 4 constitutes an example of “specific mark or space portion detection means” and “LPP binary signal detection means” according to the present invention.

  The waveform measurement and evaluation unit 5 is composed of a digital oscilloscope or the like, and is configured to measure the amplitude of the LPP signal and perform evaluation such as spec-in or spec-out. The waveform measurement and evaluation unit 5 constitutes an example of “specific mark or in-space LPP signal detection means”, “LPP waveform acquisition means”, and “determination means” according to the present invention.

  The drive control unit 3 includes a controller and the like, and is configured to control the overall operation of the drive unit 201. The measurement control unit 6 includes a controller and the like, and controls the overall operation of the measurement control unit 202. It is configured. The controller constituting the measurement control unit 6 may be shared with the trigger signal generating unit 4 and the controller constituting the waveform measurement and evaluation unit 5.

  Next, the detailed configuration of the RF and LPP signal generation unit 1 shown in FIG. 3 will be described with reference to FIGS. FIG. 4 is a block diagram relating to the photodetection system of the RF and LPP signal generation unit 1. FIG. 5 is a waveform diagram of the push-pull signal Spp generated together with the wobble signal Sw by the RF and LPP signal generator 1. FIG. 6 is a waveform diagram obtained on the oscilloscope of the RF signal Srf generated by the RF and LPP signal generator 1.

  In FIG. 4, the RF and LPP signal generation unit includes a four-divided photodetector 10 as a light receiving unit that receives laser light LB that is reflected light from an optical disk. The quadrant photodetector 10 has light receiving surfaces 10a, 10b, 10c, and 10d that output light receiving signals Ia, Ib, Ic, and Id, respectively. The light receiving surfaces 10a and 10b constitute an example of the “first light receiving surface” according to the present invention divided by a dividing line extending in a direction optically corresponding to the tangential direction of the track. Therefore, the light reception signals Ia and Ib which are these outputs are amplified by the amplifiers 12a and 12b, respectively, and then added by the adder 14 to obtain the first light reception output (Ia + Ib) from the first light receiving surface.

  On the other hand, the light receiving surfaces 10c and 10d constitute an example of the “second light receiving surface” according to the present invention divided by a dividing line extending in a direction optically corresponding to the tangential direction of the track. Therefore, the light reception signals Ic and Id as these outputs are amplified by the amplifiers 12c and 12d, and then added by the adder 15 to be the second light reception output (Ic + Id) from the second light receiving surface.

  Further, the difference between the first received light output (Ia + Ib) and the second received light output (Ic + Id) is calculated by the subtracter 16, that is, (Ia + Ib) − (Ic + Id) is calculated, thereby push-pull. A signal Spp is generated.

  On the other hand, a sum is calculated by the adder 17 between the first received light output (Ia + Ib) and the second received light output (Ic + Id), that is, (Ia + Ib) + (Ic + Id) is calculated, and RF A signal Srf is generated.

  The push-pull signal Spp and the RF signal Srf generated in this way have waveforms shown in FIGS. 5 and 6, for example.

  In FIG. 5, on the time axis, the push-pull signal Spp is a signal protruding from the apex on the wobble signal Sw generated according to the wobble 109 (see FIG. 2).

  In FIG. 6, a plurality of RF signals generated at different times are superimposed on the oscilloscope, and it can be seen that each RF signal has an amplitude and a phase that differ depending on the length of the mark and space. Therefore, at the time of information reproduction, it is possible to reproduce the recording data corresponding to the recording pit based on the RF signal.

  Next, detailed configurations of the trigger signal generation unit 4 and the waveform shaping and evaluation unit 5 illustrated in FIG. 3 will be described together with their operations with reference to FIGS. FIG. 7 is a block diagram of the trigger signal generation unit, and FIG. 8 is a block diagram of the LPP amplitude evaluation unit.

  In FIG. 7, the trigger signal generation unit includes buffers 21 and 2, and binarization circuits 22 and 14 T in order to generate a gate pulse Pga from the RF signal Srf input from the RF and LPP signal generation unit 1 (see FIG. 4). A space detector 23 and a gate pulse generator 24 are provided. The trigger signal generation unit also detects a time-adjusted LPP binarized signal Sppbd from the push-pull signal Spp input from the RF and LPP signal generation unit 1 (see FIG. 4). A delay circuit (time adjustment circuit) 33 is provided. The trigger signal generation unit further calculates a logical product of the gate pulse Pga output from the gate pulse generator 24 and the time-adjusted LPP binary signal Sppbd output from the delay circuit 33 in order to generate the trigger signal Str. Therefore, a logical product circuit (AND circuit) 41 that outputs the trigger signal Str is provided.

  In addition, the trigger signal generation unit includes a buffer 36 that outputs the push-pull signal Spp output from the buffer 31 as a measurement LPP signal Sme by buffering.

  The trigger signal generation unit further includes a buffer 37 that outputs a slice level signal Ssl indicating the slice level SL2 by buffering the slice level SL2 used in the comparator 32.

  The configuration of each component shown in FIG. 7 will be described in more detail along with their operations.

  In FIG. 7, the binarization circuit 22 generates a binarized RF signal Srfb, for example, by comparing the RF signal Srf output from the buffer 21 with the slice level SL1 set to a predetermined value. In the binarized RF signal Srfb, a 3T to 11T mark portion and a space portion appear, and a synchronous 14T mark portion and a space portion are also appropriate. Will appear at a certain frequency. Then, only the 14T space signal is detected by the 14T space detector 23. Subsequently, for this 14T space detection signal, a gate pulse Pga having a gate width of 10T, for example, is generated by the gate pulse generator 24. The gate width may be 12T or 8T, for example.

  On the other hand, the comparator 32 generates a binarized LPP signal Spppb by comparing the push-pull signal Spp output from the buffer 31 with the slice level SL2. Here, the set value of the slice level SL2 is set to a predetermined level described later. Subsequently, the delay circuit 33 adjusts the delay width (Delay) by the delay circuit 33 in order to match the time (timing) on the LPP signal side with respect to the shift on the time axis generated when the gate pulse Pga is generated from the RF signal Srf. . In this way, the LPP binarized signal output Sppbd in which the deviation on the time axis with respect to the gate pulse Pga is corrected is generated.

  Here, the logical product of the 10T space width gate pulse Pga and the time-adjusted LPP binary signal Sppbd is taken by the logical product circuit 41, and as a result, the trigger signal Str is generated.

  In parallel with the output of the trigger signal Str as described above, the measurement LPP signal Sme is output from the buffer 36, and the slice level signal Ssl is output from the buffer 37.

  In FIG. 8, the waveform measurement and evaluation unit samples the measurement LPP signal Sme input from the buffer 36 (see FIG. 7) using the trigger signal Str input from the AND circuit 41 (see FIG. 7) as a trigger. A digital oscilloscope 51, a counter 52, and a PC (personal computer) 53 are provided in order to perform evaluation including LPP amplitude measurement.

  The configuration of each component shown in FIG. 8 will be described in more detail along with their operations.

  In FIG. 8, the trigger signal Str output from the logic circuit 41 (see FIG. 7) is input to the digital oscilloscope 51, and the measurement LPP signal Sme output from the buffer 36 (see FIG. 7) is input. , And input to the input terminal for the measurement object. Further, the slice level signal Ssl output from the buffer 37 (see FIG. 7) is input to the digital oscilloscope 51 to another input terminal.

  The digital oscilloscope 51 acquires the measurement LPP signal Sme when the trigger is applied by the trigger signal Str. That is, since the trigger signal Str is the LPP binarized signal Sppbd existing in the gate pulse Pga corresponding to the 14T space, only the LPP signal existing in the 14T space of the measurement LPP signal Sme is acquired by the digital oscilloscope 51. Will be. Further, since the trigger signal Str is also a signal obtained by binarizing the original push-pull signal Spp at the slice level SL2, when the LPP amplitude of the Spp is equal to or lower than the slice level SL2, the trigger signal Str is not binarized and exists in the 14T space. However, it is not acquired by the digital oscilloscope 51. Therefore, it is necessary to appropriately set the slice level SL2 in order to perform measurement and evaluation on the amplitude of the LPP signal based on the same criteria. In this embodiment, the slice level SL2 is set so that the slice level signal Ssl is at a predetermined ratio (for example, 20% of the maximum amplitude value) with respect to the maximum value AP (max) of the LPP signal amplitude acquired by the digital oscilloscope 51. Set.

  By counting the trigger output of the digital oscilloscope 51 by the counter 52, it is counted how many times the LPP waveform in the 14T space in the measurement LPP signal Sme has been acquired. More specifically, when a trigger is actually applied in the digital oscilloscope 51, a trigger output pulse (only one pulse) is output from the digital oscilloscope 51. Therefore, by counting the output trigger output pulse by a counter 52 such as a universal pulse counter, the number of triggers by the digital oscilloscope can be detected.

  For example, when a predetermined number of counts such as 1000 preset is performed, the digital oscilloscope 51 has acquired the LPP signal waveform 1000 times, and the 1000 waveforms can be displayed in duplicate. At this time, by measuring the maximum value AP (max) and the minimum value AP (min) regarding the amplitude in the LPP waveform displayed in duplicate, it is possible to calculate an AR value that is a ratio of the minimum value to the maximum value. Become.

  Then, it is determined whether the AR value exceeds a predetermined threshold value such as 40% or has reached the predetermined threshold value. A large AR value leads to a wide binarizable range for the LPP signal and high detection accuracy for pre-pit detection. Therefore, if it is determined that the AR value has exceeded the predetermined threshold or has reached the predetermined threshold, the optical disc 100 to be evaluated is spec-in for the LPP amplitude. On the other hand, if it is determined that the AR value does not reach the predetermined threshold value, the optical disc 100 to be evaluated is out of spec for the LPP amplitude.

  As described above, the setting of the slice level SL2 in the trigger signal generation unit 4, the acquisition of the LPP signal waveform by the digital oscilloscope 51 and the counter 52, the amplitude measurement, and the like can be controlled by the PC 53 or the like. Yes, a series of evaluations can be automated including determination of the measured AR value.

  As a result, according to the present embodiment, it is possible to determine the detection accuracy of the LPP signal in the 14T space portion by detecting the LPP signal in the 14T space portion and evaluating the amplitude level.

  Next, with reference to FIGS. 9 to 13, the evaluation of the amplitude level of the LPP signal using the AR value as in the present embodiment will be examined by comparing with the comparative example. FIG. 9 shows the measurement LPP signal when the trigger signal Str and the measurement LPP signal Sme are input to the digital oscilloscope 51 (see FIG. 8) in the above-described embodiment and the trigger signal Str is applied. Sme is displayed. Here, for example, the waveforms of 1000 LPP signals are shown. FIG. 10 is a schematic waveform diagram showing the relationship between AP (max) and AP (min) and the slice level Y% in such a waveform, and FIG. 11 shows the waveform when the spec-in is evaluated. FIG. 12 is a waveform diagram having the same meaning as in FIG. 10 according to the specific example of FIG. 10, and FIG. 12 is a waveform diagram having the same meaning as in FIG. On the other hand, FIG. 13 shows waveforms of LPP signals displayed by a digital oscilloscope in the AR evaluation method as a comparative example.

  In FIG. 9, the LPP signal in the 14T space is sampled using the trigger signal Str generated by using the gate pulse Pga (see FIG. 8) in the 10T space. At this time, for example, the LPP slice level Ssl (LPP slice level) for generating the LPP binary signal Sppb set at the slice level SL2 (see FIG. 7) shown in FIG. 7 is 20% of AP (max). Is set to The waveform of the LPP signal triggered at the trigger timing by the trigger signal Str is displayed on the digital oscilloscope 51 (see FIG. 8) in an overlapping manner. Such overlapping display is performed for 1000 triggers, for example, by counting the number of triggers (that is, the number of waveform acquisitions) by the counter 52 (see FIG. 8). The AR value is obtained from the waveform of the LPP signal displayed in duplicate. As described above, the slice level signal Ssl is set to a predetermined ratio (that is, 20% of AP (max) in this example) with respect to the maximum value AP (max) of the LPP signal amplitude acquired by the digital oscilloscope 51. Since the slice level SL2 is set, the digital oscilloscope 51 can measure and evaluate the amplitude of the LPP signal based on the same reference.

  As shown in FIG. 10, AP (max) means, for example, the maximum amplitude among 1000 LPP signals, and AP (min) means, for example, the minimum amplitude among 1000 LPP signals. LPP slice level is defined as Y% of AP (max). In the specific example of FIG. 9, Y = 20% is set.

  As shown in FIG. 11, if AP (min) is sufficiently larger than the slice level (LPP slice level) (in this example, 40% or more of AP (max)), it is shown as “eye” in the figure. It can be determined that the gap from the slice level to AP (min) is sufficiently large, and at this time, there are very few LPP signals having an amplitude smaller than the slice level for binarizing the LPP. Here, for a slice level (LPP slice level) that is 20% of AP (max), when the AR value (= AP (min) / AP (max)) is provided with a standard value of 40%, for example, The standard value is satisfied. That is, the optical disc 100 is evaluated as spec-in. In this case, it can be said that the detection accuracy of the LPP signal in the 14T space portion of the optical disc 100 to be evaluated is sufficiently high.

  When the interval between the slice level and AP (min) is not large (a value of 40% or less of AP (max)), or as shown in FIG. It can be determined that the gap from the slice level to AP (min) is small or almost absent, and at this time, there are many LPP signals having an amplitude smaller than the slice level for binarizing the LPP. In this case, naturally, the AR value (= AP (min) / AP (max)) cannot exceed the standard value of 40%, for example. That is, the optical disc 100 is evaluated as spec-out. In this case, it can be said that the detection accuracy of the LPP signal in the 14T space portion in the optical disc 100 to be evaluated is low.

  On the other hand, in the case of the comparative example shown in FIG. 13, as in the case of the traditional AR evaluation method, regardless of the 14T space, that is, without using the trigger signal Str according to the above-described embodiment, All LPP signals existing in the recording mark and space portion in the groove track after recording are acquired.

  As shown in FIG. 13, in the comparative example, when the AR value is 0%, the degree of variation in the amplitude of the LPP signal is very large depending on the presence / absence of the recording mark or the length of the recording space. Since it is large, AP (min) is very small. When the AR value is 0% in this way, “eye” as shown in FIGS. 11 and 12 is not opened at all. Generally, after recording, the amplitude of the LPP signal is small when the recording mark portion is adjacent to the LPP, and on the other hand, the amplitude of the LPP signal is large when the recording space portion is adjacent to the LPP even after recording. It is considered. As described above, in the comparative example in which the amplitude of the LPP signal is greatly changed, in which the influence of the recording mark and the space in the groove track adjacent to the LPP is mixed, it is difficult to evaluate the LPP amplitude only in the 14T space portion. That is, it is considered that the conventional AR evaluation method has the same problem as the comparative example.

  On the other hand, as in this embodiment, it is extremely reasonable to selectively sample only the LPP signal in a space portion having a predetermined length such as a 14T space portion and evaluate the amplitude thereof.

  As described above in detail, according to the present embodiment, it is possible to more accurately determine the detection level of the signal for the LPP in the RF signal space portion.

  Next, a modification of the present embodiment will be described with reference to FIGS. Here, FIGS. 14 and 15 are block diagrams of a trigger signal generation unit according to a modification having the same purpose as in FIG. 7. 14 and 15, the same reference numerals are given to the same components as those in FIG. 7, and description thereof will be omitted as appropriate.

  As shown in FIG. 14, in one modification, instead of the comparator 32, the delay circuit 33, and the buffer 37 according to the above-described embodiment (see FIG. 7), the push-pull signal Spp that is an analog output from the buffer 31 is used. A delay circuit (time adjustment circuit) 233 that performs delay processing (that is, time adjustment processing) in an analog format is provided. Further, an analog switch 241 is provided instead of the AND circuit 41 according to the above-described embodiment. The trigger signal Str is configured to be selectively output via the analog switch 241. As described above, according to one modification, it is possible to generate the trigger signal Str by processing the push-pull signal Spp in an analog form.

  Alternatively, as shown in FIG. 15, in another modification, the configuration of the buffer 36 is removed from the one modification shown in FIG. 14, and the measurement LPP signal Sme is passed through the buffer 31 and the delay circuit (time adjustment circuit) 233. The analog switch 241 selectively outputs the signal. As described above, according to another modification, the trigger signal Str is generated by processing the push-pull signal Spp in an analog form using a simpler configuration than that of the first modification (see FIG. 14). Is also possible.

  In addition, according to the present embodiment, it can be applied to both a synchronous recording method in which data recording is performed in synchronization with the LPP and an asynchronous recording method in which data recording is performed asynchronously with respect to the LPP. It is very advantageous. Compared to the synchronous recording method in which the LPP and the 14T space portion are synchronized, in the asynchronous recording method in which the LPP is not synchronized, there are fewer LPPs present in the 14T space portion. For this reason, the number of LPP signals that can be detected within the same time is smaller in the asynchronous method, but it is a predetermined number as in this embodiment in both the synchronous recording method and the asynchronous recording method. By obtaining n waveforms as an evaluation condition, even if there is a slight change in the time required for measurement, the accuracy of the evaluation is hardly affected. That is, the accuracy of evaluation is maintained high regardless of the detection frequency of the LPP signal corresponding to the recording method. Furthermore, although the detection frequency of the LPP signal is generally different between the inner circumference side and the outer circumference side of the optical disc 100 (generally, the LPP is less at the outer circumference side), according to this embodiment in which the waveform is acquired a predetermined number of times, It is also very useful in the sense that accurate evaluation can be performed regardless of the inner and outer circumferences.

  Further, the present invention can be appropriately changed without departing from the gist or idea of the present invention that can be read from the claims and the entire specification, and an LPP amplitude evaluation method and apparatus, and an LPP amplitude measurement method that involve such a change. Also, devices and the like are also included in the technical idea of the present invention.

The basic structure of the optical disk based on an Example is shown, the upper part is a schematic plan view, and the lower part is a schematic conceptual diagram of a recording area structure. It is the elements on larger scale in the recording surface of the optical disk based on an Example. It is a whole block diagram of the LPP amplitude evaluation apparatus which concerns on an Example. It is a block diagram which concerns on the photon detection system of the RF and LPP signal generation part based on an Example. It is a waveform diagram of the push-pull signal Spp generated together with the wobble signal Sw by the RF and LPP signal generator according to the embodiment. It is a wave form diagram obtained on a digital oscilloscope of RF signal Srf generated by RF and LPP signal generation part concerning an example. It is a block diagram of the trigger signal generation part which concerns on an Example. It is a block diagram of the waveform shaping and evaluation part which concerns on an Example. It is a characteristic view which shows the waveform of the LPP signal sampled with the digital oscilloscope in an Example. It is the typical waveform diagram which showed the relationship between AP (max) and AP (min), and a slice level in the waveform sampled with the digital oscilloscope in an Example. FIG. 12 is a waveform diagram having the same concept as in FIG. 11, according to a specific example of a waveform when it is evaluated as spec-in in the embodiment. FIG. 12 is a waveform diagram having the same concept as in FIG. 11, according to a specific example of a waveform when it is evaluated as spec-out in the embodiment. It is a characteristic view which shows the waveform of the LPP signal displayed with the digital oscilloscope in AR evaluation method of a comparative example. It is a block diagram of the trigger signal generation part which concerns on one modification of a present Example. It is a block diagram of the trigger signal generation part which concerns on the other modification of a present Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... RF, LPP signal generation part 4 ... Trigger signal generation part 5 ... Waveform measurement and evaluation part 22 ... Comparator 23 ... 14T space detector 24 ... Gate pulse generator 32 ... Comparator 33 ... Delay circuit 41 ... AND circuit 51 ... Digital oscilloscope 52 ... counter 53 ... PC (personal computer)
100 ... Optical disc LPP ... Land pre-pit

Claims (12)

Land pre-pit amplitude evaluation method for evaluating the amplitude of an LPP signal based on the land pre-pit in an optical disc having land pre-pits formed in advance on a land track and having marks and spaces alternately recorded on a groove track Because
An irradiation step of irradiating the optical disc with reading light;
A light receiving step of receiving reflected light from the optical disk based on the reading light;
A push-pull signal generation step for generating a push-pull signal based on the received reflected light;
An RF signal generation step of generating an RF signal based on the received reflected light;
An RF binarized signal generating step of generating an RF binarized signal by binarizing the RF signal;
A specific mark or space portion detection step of detecting an RF binary signal mark or space portion corresponding to a specific mark or space having a predetermined length among the marks and spaces on the generated RF binary signal; and
A specific mark or in-space LPP signal detection step of detecting the LPP signal present in the detected RF binarized signal mark or space on the time axis as a specific mark or in-space LPP signal;
An LPP waveform acquisition step of acquiring the waveform of the detected specific mark or in-space LPP signal n times (where n is a natural number of 2 or more);
A determination step of determining whether the ratio of the minimum value to the maximum value of the amplitude of the waveform acquired n times exceeds a predetermined threshold value or reaches the predetermined threshold value. Pit amplitude evaluation method. The specific mark or in-space LPP signal detection step includes:
An LPP binarized signal generating step of generating an LPP binarized signal by binarizing the LPP signal at a predetermined slice level from the generated push-pull signal;
Among the generated LPP binarized signals, the LPP included in the generated push-pull signal using, as a trigger signal, the detected RF binarized signal mark or the one existing in the space portion on the time axis The land pre-pit amplitude evaluation method according to claim 1, wherein the specific mark or the in-space LPP signal is detected by detecting a signal.   The land pre-pit amplitude according to claim 2, wherein the LPP binary signal generation step sets the slice level at a predetermined ratio with respect to the maximum value of the amplitude of the waveform acquired n times. Evaluation methods.   The land pre-pit amplitude evaluation according to any one of claims 1 to 3, wherein the LPP waveform acquisition step includes an LPP waveform overlap display step of overlappingly displaying the waveform acquired n times. Method.   5. The land pre-pit amplitude evaluation method according to claim 4, wherein the LPP waveform overlap display step displays the waveform acquired n times on a digital oscilloscope in an overlapping manner. The specific mark or space portion detection step includes a gate pulse generation step of generating a gate pulse in the detected RF binary signal mark or space portion on the time axis,
6. The specific mark or in-space LPP signal detection step detects the specific mark or in-space LPP signal based on the generated gate pulse. 6. Land pre-pit amplitude evaluation method. The LPP waveform acquisition process is as follows:
Generating a gate pulse in the detected RF binarized signal mark or space on the time axis; and
A trigger signal generating step of outputting, as the trigger signal, an LPP binarized signal existing in the gate pulse on the time axis among the generated LPP binarized signals,
The land pre-pit according to claim 2 or 3, wherein the specific mark or in-space LPP signal detection step detects the specific mark or in-space LPP signal using the output trigger signal. Amplitude evaluation method.   The land according to any one of claims 1 to 7, wherein the mark or space portion detection step detects an RF binary signal space portion corresponding to a 14T space as the specific mark or space. Prepit amplitude evaluation method.   The LPP waveform acquisition step includes a waveform acquisition number determination step of counting the number of trigger output pulses of the digital oscilloscope in order to acquire the waveform of the detected specific mark or in-space LPP signal n times. The land pre-pit amplitude evaluation method according to claim 4. Land pre-pit amplitude measurement method for measuring the amplitude of an LPP signal based on the land pre-pit in an optical disc having land pre-pits formed in advance on a land track and having marks and spaces alternately recorded on a groove track Because
An irradiation step of irradiating the optical disc with reading light;
A light receiving step of receiving reflected light from the optical disk based on the reading light;
A push-pull signal generation step for generating a push-pull signal based on the received reflected light;
An RF signal generation step of generating an RF signal based on the received reflected light;
An RF binarized signal generating step of generating an RF binarized signal by binarizing the RF signal;
A specific mark or space portion detection step of detecting an RF binary signal mark or space portion corresponding to a specific mark or space having a predetermined length among the marks and spaces on the generated RF binary signal; and
A specific mark or in-space LPP signal detection step of detecting the LPP signal present in the detected RF binarized signal mark or space on the time axis as a specific mark or in-space LPP signal;
A land prepit amplitude measuring method comprising: an LPP waveform acquisition step of acquiring a waveform of the detected specific mark or in-space LPP signal. Land pre-pit amplitude evaluation apparatus for evaluating the amplitude of an LPP signal based on the land pre-pit in an optical disc having land pre-pits formed in advance on a land track and having marks and spaces alternately recorded on a groove track Because
Irradiating means for irradiating the optical disk with reading light;
A light receiving means for receiving reflected light from the optical disk based on the reading light;
Push-pull signal generating means for generating a push-pull signal based on the received reflected light; and
RF signal generation means for generating an RF signal based on the received reflected light;
RF binarized signal generating means for generating an RF binarized signal by binarizing the RF signal;
A specific mark or space portion detection means for detecting an RF binary signal mark or space portion corresponding to a specific mark or space having a predetermined length among the mark and space on the generated RF binary signal;
A specific mark or in-space LPP signal detection means for detecting the LPP signal present in the detected RF binarized signal mark or space on the time axis as a specific mark or in-space LPP signal;
LPP waveform acquisition means for acquiring the waveform of the detected specific mark or in-space LPP signal n times (where n is a natural number of 2 or more);
Determination means for determining whether the ratio of the minimum value to the maximum value of the amplitude of the waveform acquired n times exceeds a predetermined threshold value or reaches the predetermined threshold value. Pit amplitude evaluation device. Land pre-pit amplitude measuring device for measuring the amplitude of an LPP signal based on the land pre-pit in an optical disc having land pre-pits formed in advance on a land track and having marks and spaces alternately recorded on a groove track Because
Irradiating means for irradiating the optical disk with reading light;
A light receiving means for receiving reflected light from the optical disk based on the reading light;
Push-pull signal generating means for generating a push-pull signal based on the received reflected light; and
RF signal generation means for generating an RF signal based on the received reflected light;
RF binarized signal generating means for generating an RF binarized signal by binarizing the RF signal;
A specific mark or space portion detection means for detecting an RF binary signal mark or space portion corresponding to a specific mark or space having a predetermined length among the mark and space on the generated RF binary signal;
A specific mark or in-space LPP signal detection means for detecting the LPP signal present in the detected RF binarized signal mark or space portion as a specific mark or in-space LPP signal on the time axis, and the detected specific A land pre-pit amplitude measuring device comprising: an LPP waveform acquisition means for acquiring a waveform of an LPP signal in a mark or space.

Images