JP2006236403A - Optical disk unit and phase shift detection method applied to optical disk unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect a phase shift of a reproduction signal to improve the recording precision of an optical disk in an optical disk drive. <P>SOLUTION: A first measuring pulse-row signal generation circuit 23 generates a first measuring pulse-row signal that rises in synchronization with the reproduction signal and falls in synchronization with a clock signal. A second measuring pulse-row signal generation circuit 24 generates a second measuring pulse-row signal that rises in synchronization with the clock signal and falls in synchronization with the reproduction signal. A jitter measuring unit 25 measures jitters in the first measuring pulse train signal and the second measuring pulse train signal. The phase shift in the reproduction signal is detected based on the measured jitters. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical disc apparatus that records data by irradiating an optical disc such as a CD and a DVD with laser light, and a phase shift detection method applied to the optical disc apparatus.

  In general, in an optical disc apparatus that records data on an optical disc such as a CD or DVD, an optimum basic light amount and strategy (pulse) of a laser beam emitted from a laser light source is used for the purpose of accurately forming a recording mark on a recording layer of the optical disc. (Light emission waveform rule) is set. The strategy defines the pulse waveform of the laser beam emitted from the laser light source for each of a plurality of signal lengths included in the recording signal, that is, the number of pulses, the width of each pulse, the amount of light, the interval between the pulses, and the like. . This strategy is set based on the jitter of the reproduction signal obtained by reproducing the inspection data recorded on the optical disc.

For example, in the optical disc apparatus described in Patent Document 1 below, inspection data is recorded in a predetermined inspection area of the optical disc, and the recorded inspection data is reproduced to measure the jitter of the reproduced signal. In this case, the measured jitter is a pulse width distribution (variation) of each pulse of the reproduction signal. The strategy of the laser light emitted from the laser light source is set so that the measured jitter is minimized.
JP 2004-46954 A

  However, when the strategy is corrected and the pulse width of each pulse of the reproduction signal is adjusted, the phase of each pulse may shift. Specifically, the rising timing and falling timing of each pulse may deviate from the rising timing and falling timing of the clock signal. This is because the phase shift of each pulse of the reproduction signal is not considered when correcting the strategy. Specific examples are shown in FIGS. FIG. 4A shows a pulse waveform of a reproduction signal reproduced from a recording mark formed on the recording layer of the optical disc. In this example, the signal length of a low-level signal having a signal length of 3T is 2.5T, and the falling timing of the pulse is advanced by 0.5T with respect to the clock signal. For this reason, the signal length of the high-level signal having a signal length of 5T following the low-level signal having a signal length of 3T is longer than the original 5T signal length by 0.5T, and the rising timing of the pulse is relative to the clock signal. It is advanced by 0.5T.

  In this case, when each jitter of the high level signal and the low level signal is measured, the operator can confirm that the low level signal having the signal length of 3T has a signal length of 2.5T from the jitter of the low level signal having the signal length of 3T. Although it can be recognized, the high level signal following the signal length 3T is not limited to the signal length 5T as shown in FIGS. From the jitter of each signal length, it cannot be recognized that the falling timing of the low-level signal having a signal length of 3T is advanced by 0.5T with respect to the clock signal.

  For this reason, for example, as shown in FIG. 4B, the operator widens the pulse width of a pulse having a signal length of 2.5T by 0.25T on one side and changes the signal length to 3T by changing the laser light strategy. To do. As a result, a low-level signal having a signal length of 2.5T becomes a low-level signal having a signal length of 3T, but a high-level signal having a signal length of 4T that precedes the low-level signal having a signal length of 3T has a signal length of 0.25T. And the falling timing of the pulse advances by 0.25T with respect to the clock signal. Further, a high-level signal having a signal length of 5T following a low-level signal having a signal length of 3T has a signal length that is shortened by 0.25T and changes to a signal length that is 0.25T longer than the original signal length. At the same time, the rising timing of the pulse with respect to the clock signal changes to a pulse advanced by 0.25T.

  When the jitter of the high level signal and the low level signal is measured in this state, the jitter of the signal length 3T of the low level signal is minimized, but the jitter of the signal length of the high level signal is not minimized. . However, the signal length of the high-level signal existing before and after the low-level signal having the signal length 3T is not limited to the signal lengths 4T and 5T shown in FIGS. Therefore, it cannot be recognized that the reason why the jitter of each signal length of the high-level signal is not minimized is due to the shift of the falling timing and the rising timing, ie, the phase shift, of the low-level signal having the signal length of 3T. For this reason, even if the laser light strategy is adjusted based on the low-level signal and high-level signal jitter of each pulse of the reproduction signal, the phase shift of each pulse is unknown. This is not an adjustment, and the phase shift of each pulse is not eliminated. As a result, there is a problem in that the recording mark cannot be accurately formed on the recording layer of the optical disc, and the recording accuracy is poor.

  The present invention has been made to cope with the above-described problem, and its object is to set a strategy of laser light emitted from a laser light source in consideration of a phase shift of each pulse of a signal recorded on an optical disc. An object of the present invention is to provide an optical disc apparatus capable of improving the recording accuracy of signals with respect to the optical disc.

  In order to achieve the above object, a feature of the present invention is that a laser beam emitted from a laser light source is irradiated onto an optical disc, and a laser beam reflected by the optical disc is used to generate a pulse train corresponding to data recorded on the optical disc. In the optical disc apparatus provided with the reproduction signal generation means for generating the reproduction signal, the clock signal generation means for generating the clock signal based on the reproduction signal and the timing of one of the rising change and the falling change. The clock signal generated by the clock signal generating means is synchronized with the rising timing or falling timing of the clock signal, and the timing of the other of the rising change and falling change is set to the rising timing or falling timing of the reproduction signal. Synchronized first measurement buffer A first measurement pulse train signal generating means for generating a scan sequence signal is to have a jitter measuring unit for measuring jitter of the first measurement pulse train signal generated by the first measurement pulse train signal generating means.

  According to the feature of the present invention configured as described above, the timing of one change is synchronized with the rise timing or fall timing of the clock signal, and the timing of the other change is synchronized with the rise timing or fall timing of the reproduction signal. The jitter of the first measurement pulse train signal is measured. In this case, the rise timing or fall timing of the reproduction signal synchronized with the timing of the other change of the first measurement pulse train signal is not synchronized with the timing when the clock signal rises or falls The pulse width of the first measurement pulse train signal generated is different even if the pulse width of the pulse of the reproduction signal is the same. That is, the difference between the pulse widths of these two first measurement pulse train signals represents a phase shift in the rising timing or falling timing of the reproduction signal with respect to the clock signal. Therefore, by measuring the pulse width distribution (variation) of the first measurement pulse train signal, that is, by measuring the jitter, it is possible to detect the phase shift of the rising timing or falling timing of the reproduction signal. Thereby, the operator can set the strategy of the laser beam emitted from the laser light source in consideration of the phase shift of each pulse of the signal recorded on the optical disc, and the signal recording accuracy on the optical disc can be improved. can do.

  Another feature of the present invention is that the timing of the other change of the rising change and falling change is synchronized with the rising timing or falling timing of the clock signal generated by the clock signal generating means, A second measurement pulse train signal generating means for generating a second measurement pulse train signal in which the timing of one of the rising change and falling change is synchronized with the rising timing or falling timing of the reproduction signal; The jitter measuring means measures the jitter of the second measurement pulse train signal in addition to the first measurement pulse train signal.

  According to another feature of the present invention configured as described above, the timing of the other change is synchronized with the rise timing or fall timing of the clock signal, and the timing of the one change is the rise timing or rise timing of the reproduction signal. The jitter of the second measurement pulse train signal synchronized with the falling timing is measured. Thereby, it is possible to detect a phase shift with respect to the clock signal at both the rising timing and falling timing in the reproduction signal. For this reason, it is possible to set the strategy of the laser light emitted from the laser light source in consideration of the phase difference between the rising timing and the falling timing of each pulse, and to improve the recording accuracy of the signal to the optical disc. it can.

  Another feature of the present invention resides in that a display device for displaying the jitter measured by the jitter measuring means is provided. Thereby, the operator can easily recognize the measurement result of the jitter measured by the jitter measuring means.

  Another feature of the present invention is that there is laser light correction means for correcting the characteristics of the laser light emitted from the laser light source based on the jitter measured by the jitter measurement means when data is recorded on the optical disk. It is to have done. According to this, the phase shift of each pulse of the reproduction signal is detected based on the jitter measured by the jitter measuring means, and the characteristics of the laser beam emitted from the laser light source based on the detected phase shift, For example, the number of pulses for each signal length, the width of each pulse, the amount of light, the interval between pulses, and the like can be corrected early. As a result, the efficiency of the setting operation can be improved as compared with the conventional case where the strategy is set based on the jitter which is the pulse width distribution (variation) of each pulse of the reproduction signal.

  The present invention can be implemented not only as an apparatus invention but also as a method invention.

  Hereinafter, an embodiment of an optical disk device according to the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram of an optical disc inspection apparatus for inspecting an optical disc DK such as a CD, DVD, or Blu-Ray disc. The optical disc inspection device is a device that records a predetermined inspection signal on a recording layer of the optical disc DK and reproduces the recorded inspection signal to determine whether the optical disc DK is good or bad.

  This optical disc inspection apparatus includes a turntable 11 on which an optical disc DK is placed and fixed. The turntable 11 is rotationally controlled by a spindle motor (not shown) so that a light spot formed on the optical disc DK rotates at a constant linear velocity or a constant angular velocity with respect to the optical disc DK. An optical pickup device 12 is disposed on the side facing the optical disc DK. The light spot formed on the optical disk moves in the radial direction with respect to the optical disk DK by moving the spindle motor or the optical pickup device 12 in the radial direction of the optical disk DK by a feed motor (not shown). The spot moves spirally on the optical disk DK. Since the control of the spindle motor and the feed motor is not directly related to the present invention, the description thereof is omitted.

  The optical pickup device 12 is an optical device that records a signal on the optical disc DK or reproduces a signal recorded on the optical disc DK, and includes a laser light source, a collimating lens, a beam splitter, a quarter wavelength plate, an objective lens, A condenser lens, a cylindrical lens, a quadrant photodetector, a focus actuator, a tracking actuator, and the like are provided. The optical pickup device 12 irradiates the optical disk DK with laser light from a laser light source to form a light spot on the optical disk DK, and receives reflected light from the light spot from the optical disk DK with a four-divided photodetector.

  The four-divided photodetector is composed of four light receiving elements separated by a dividing line, and outputs a received light signal proportional to the amount of received reflected light to the amplifier circuit 13. The light reception signal output from the quadrant photodetector is used for focus servo control and tracking servo control of the objective lens by the focus servo control circuit, tracking servo control circuit, focus actuator and tracking actuator. Since the focus servo control and tracking servo control of the objective lens are not directly related to the present invention, detailed description thereof is omitted.

  The amplifying circuit 13 amplifies the received light signal output from the quadrant photodetector and outputs the amplified signal to the reproduction signal generating circuit 14. The reproduction signal generation circuit 14 generates a reproduction signal (a so-called sum signal) obtained by adding up all four light reception signals from the four-divided photodetector and outputs the reproduction signal to the waveform equalization circuit 15. The waveform equalization circuit 15 is configured by an equalization circuit, and outputs a signal obtained by correcting the amplitude of the reproduction signal output from the reproduction signal generation circuit 14 according to the frequency to the binarization circuit 16. The binarization circuit 16 binarizes the signal output from the waveform equalization circuit 15, that is, converts the signal into a pulse train signal, converts the clock signal generation circuit 21, the reference signal generation circuit 22, and the first measurement pulse train signal generation circuit 23. And output to the second measurement pulse train signal generation circuit 24 and the jitter measuring device 25, respectively.

  The clock signal generation circuit 21 includes a PLL circuit, generates a clock signal based on the binarized reproduction signal output from the binarization circuit 16, and outputs the clock signal to the reference signal generation circuit 22. Specifically, the reproduction signal output from the binarization circuit 16 has a signal length multiplied by a clock period T (3T to 11T for CD, 3T to 11T, 14T for DVD, and 2T to 8T for Blu-ray Disc. The clock signal generation circuit 21 generates a clock signal for demodulating the recording signal from the reproduction signal.

  The reference signal generation circuit 22 includes a flip-flop circuit, and generates a reference signal using the binarized reproduction signal output from the binarization circuit 16 and the clock signal output from the clock signal generation circuit 21. To do. Specifically, a pulse train signal corresponding to each level of the reproduction signal at the falling timing of the clock signal is generated as a reference signal. In this case, the pulse width of each pulse of the reference signal has a signal length obtained by multiplying the clock period T. Further, since each pulse of the reference signal is synchronized with the falling timing of the clock signal, it is delayed by 0.5T compared to a case where each pulse of the corresponding reproduction signal is synchronized with each rising timing of the clock signal. . The reference signal generation circuit 22 outputs the generated reference signal to the first measurement pulse train signal generation circuit 23 and the second measurement pulse train signal generation circuit 24, respectively.

  The first measurement pulse train signal generation circuit 23 includes a flip-flop circuit, and uses the binarized reproduction signal output from the binarization circuit 16 and the reference signal output from the reference signal generation circuit 22. A first measurement pulse train signal is generated. Specifically, a pulse train signal that rises in synchronization with the rise timing of each pulse of the reproduction signal and changes in fall in synchronization with the fall timing of each pulse of the reference signal is generated as the first measurement pulse train signal. . The first measurement pulse train signal generation circuit 23 outputs the generated first measurement pulse train signal to the jitter measuring device 25.

  The second measurement pulse train signal generation circuit 24 includes a flip-flop circuit, and uses the binarized reproduction signal output from the binarization circuit 16 and the reference signal output from the reference signal generation circuit 22. A second measurement pulse train signal is generated. Specifically, a pulse train signal that rises in synchronization with the rise timing of each pulse of the reference signal and changes in fall in synchronization with the fall timing of each pulse of the reproduction signal is generated as the second measurement pulse train signal. . The second measurement pulse train signal generation circuit 24 outputs the generated second measurement pulse train signal to the jitter measuring device 25.

  The jitter measuring device 25 is a measuring device that measures the jitter of each pulse of the input pulse train signal. Specifically, the jitter measuring device 25 includes a time interval analyzer, and the binarized reproduction signal output from the binarization circuit 16 and the first measurement pulse train signal generation circuit 23 output from the first measurement pulse train signal generation circuit 23. The pulse width distribution (variation) of each pulse of the measurement pulse train signal and the second measurement pulse train signal output from the second measurement pulse train signal generation circuit 24 is measured, and the respective measured values will be described later. Output to.

  Connected to the optical pickup device 12 is a laser drive circuit 26 for driving and controlling a built-in laser light source. The laser drive circuit 26 emits laser light of the light amount set by the laser power setting circuit 27 from the laser light source, and turns on / off the laser light source based on the inspection recording signal output from the recording signal generation circuit 28 Or operate at high level and low level. The laser power setting circuit 27 controls the operation and stop of the laser light source by controlling the laser driving circuit 26 in accordance with a command from the computer device 30, and the emitted light quantity of the laser light at the time of operation is set as a high power for recording. Switch to low power for playback. The recording signal generation circuit 28 generates an inspection recording signal corresponding to the inspection data output from the computer device 30 based on the strategy (pulse emission waveform rule) set by the strategy setting circuit 29 to generate a laser driving circuit. 26.

  The strategy setting circuit 29 sets a strategy for each signal length in the pulse train signal based on the strategy setting signal output from the computer 30 and outputs the strategy to the recording signal generation circuit 28. Here, the strategy is set in order to accurately form a recording mark on the recording layer of the optical disc DK. The pulse waveform for each signal length in the pulse train signal, that is, the number of pulses, the width of each pulse, the amount of light, and each Specify the pulse interval.

  The computer device 30 is constituted by a microcomputer including a CPU, ROM, RAM, hard disk, and the like, and inspects the optical disc DK by executing a program (not shown) according to instructions from the input device 31 including a keyboard and a mouse. At the same time, the execution process and execution result of the inspection are appropriately displayed on the output device 32 including a CRT (or liquid crystal display), a printer, and the like. In addition, the computer device 30 causes the output device 32 to display the jitter measurement results of the reproduction signal, the first measurement pulse train signal, and the second measurement pulse train signal output from the jitter measuring device 25. In addition, a jitter measuring device 25, a laser power setting circuit 27, a recording signal generation circuit 28, and a strategy setting circuit 29 are connected to the computer device 30 for controlling their operations.

  The operation of the embodiment configured as described above will be described. The operator starts operation of various circuits of the optical disc inspection apparatus including the computer device 30 by turning on a power switch (not shown). Then, an optical disc DK having an unrecorded surface to be inspected is placed on the turntable 11, and the optical disc DK is fixed on the turntable 11. Next, the operator operates the input device 31 to instruct the computer device 30 to record inspection data on the optical disc DK. In response to this instruction, the computer device 30 starts recording of inspection data in a predetermined storage area of the optical disc DK by executing a program (not shown). Specifically, the computer device 30 rotates the optical disc DK at a constant linear velocity or angular velocity, and records inspection data by forming a light spot in a predetermined recording area of the optical disc DK.

  In this case, the light quantity and strategy of the laser light emitted intermittently from the laser light source of the optical pickup device 12 are defined as a predetermined light quantity and strategy. Specifically, the computer device 30 outputs an emission light amount command signal indicating a high power light amount for recording to the laser power setting circuit 27 and outputs a signal related to the strategy setting to the strategy setting circuit 29. The laser power setting circuit 27 outputs an emitted light amount signal to the laser drive circuit 26 based on the emitted light amount command signal. The strategy setting circuit 29 sets a strategy for each signal length in the pulse train signal based on a signal related to strategy setting and outputs the strategy to the recording signal generation circuit 28. In this case, the signal related to the strategy setting represents a standard strategy for each signal length preset in the computer apparatus 30.

  Further, the computer device 30 outputs inspection data recorded on the optical disc DK to the recording signal generation circuit 28. Thus, the recording signal generation circuit 28 generates an inspection recording signal using the inspection data output from the computer device 30 based on the strategy set by the strategy setting circuit 29 and outputs the inspection recording signal to the laser drive circuit 26. To do. The laser drive circuit 26 drives the laser light source based on the emitted light amount signal and the inspection recording signal. As a result, the inspection data is recorded in a predetermined recording area of the optical disc DK by the laser light defined by the predetermined light quantity and strategy.

  Next, the operator operates the input device 31 to instruct the computer device 30 to measure the jitter of the reproduction signal. In response to this instruction, the computer device 30 starts reproduction of the inspection data recorded in the predetermined storage area of the optical disc DK by executing a program (not shown). Specifically, the computer device 30 rotates the optical disc DK at a constant linear velocity or angular velocity, and forms a light spot in the predetermined recording area of the optical disc DK. In this case, the amount of laser light emitted continuously from the laser light source of the optical pickup device 12 is regulated by the computer device 30 and the laser power setting circuit 27 to a low power amount for reproduction.

  Reflected light from the optical disk DK is received by a four-divided photodetector of the optical pickup device 12, converted into a received light signal corresponding to the amount of received light, and output to the reproduction signal generation circuit 14 via the amplifier circuit 13. The received light signal is converted into a reproduction signal by the reproduction signal generation circuit 14 and then binarized by the binarization circuit 16 to be clock signal generation circuit 21, reference signal generation circuit 22, and first measurement pulse train signal. It is output to the generation circuit 23 and the second measurement pulse train signal generation circuit 24, respectively. The clock signal generation circuit 21 generates a clock signal having a fixed period based on the binarized reproduction signal and outputs the clock signal to the reference signal generation circuit 22. The reference signal generation circuit 22 generates a reference signal that is a pulse train signal obtained by synchronizing the reproduction signal with the clock signal, and outputs the reference signal to the first measurement pulse train signal generation circuit 23 and the second measurement pulse train signal generation circuit 24, respectively.

  In this case, as shown in FIGS. 2A to 2D, the pulse width of each pulse of the reproduction signal output to the reference signal generation circuit 22 is shifted by less than ± 1T from the original signal length of each pulse. And the rising timing and falling timing of each pulse are within the range of the advance of less than 0.5T or the delay of 0.5T or less with respect to the respective rise timings of the clock signal. Therefore, a predetermined reference signal can be generated for most pulses of the reproduction signal. Since the reference signal generation circuit 22 generates a pulse train signal corresponding to each level of the reproduction signal at the falling timing of the clock signal as a reference signal, each pulse of the reference signal has an original signal length of each pulse of the reproduction signal. And a delay of 0.5T compared to the case where each pulse of the corresponding reproduction signal is synchronized with the rising timing of the clock signal.

  As shown in FIGS. 4 (A) and 4 (B), the adjustment of the strategy is related to the portion corresponding to the location where the recording mark is formed on the optical disc DK in the binarized reproduction signal, that is, Although it is a low level signal, in order to make the explanation easy to understand, in FIGS. 2A to 2D, the low level and the high level of the binarized reproduction signal are shown inverted. That is, the high-level signal of the reproduction signal shown in FIGS. 2A to 2D is actually a low-level signal that is a signal from the recording mark formed on the optical disc DK. Therefore, in the following description, the binarized reproduction signal is originally a low level signal, but will be described as a high level signal.

  2A to 2D, FIG. 2A shows a case where the rise timing and fall timing of the pulse of the reproduction signal are delayed with respect to the rise timing of the clock signal. FIG. 2B shows a case where the rising timing of the pulse of the reproduction signal is delayed and the falling timing is advanced with respect to the rising timing of the clock signal. FIG. 2C shows a case where the rise timing of the reproduction signal pulse is advanced with respect to the rise timing of the clock signal, and the fall timing is delayed. FIG. 2D shows a case where the rise timing and fall timing of the pulse of the reproduction signal are advanced with respect to the rise timing of the clock signal. Further, the signal length of the pulse of the reproduction signal shown in FIGS. 2A to 2D is 4T, and the amount of advance and delay of both timings of the pulse of the reproduction signal is 0.25T, respectively.

  The reference signal generated by the reference signal generation circuit 22 is output to the first measurement pulse train signal generation circuit 23 and the second measurement pulse train signal generation circuit 24, respectively. The first measurement pulse train signal generation circuit 23 generates a first measurement pulse train signal using the reference signal and the binarized reproduction signal. Specifically, as described above, a pulse train signal that rises in synchronization with the rise timing of each pulse of the reproduction signal and changes in fall in synchronization with the fall timing of each pulse of the reference signal is generated. In this case, when the rise timing of the pulse of the reproduction signal is synchronized with the rise timing of the pulse of the clock signal, the pulse width of the pulse of the generated first measurement pulse train signal is the pulse width of the corresponding reproduction signal. The pulse width is obtained by adding 0.5T to the signal length. This is because the pulse falling timing of the first measurement pulse train signal is synchronized with the falling timing of the reference signal delayed by 0.5T.

  On the other hand, when the rise timing of the pulse of the reproduction signal is not synchronized with the rise timing of the pulse of the clock signal, specifically, the rise timing of the pulse of the reproduction signal is advanced or delayed with respect to the rise timing of the clock signal. The pulse width of the pulse of the first measurement pulse train signal generated is set to a pulse width obtained by adding 0.5 T to the signal length of the pulse of the corresponding reproduction signal, and the advance of the pulse of the reproduction signal. Or the pulse width is increased or decreased. For example, in the first measurement pulse train signal shown in FIGS. 2A and 2B, 4 is obtained by subtracting 0.25T, which is a delay in the rising timing of the pulse of the reproduction signal, from 4.5T (4T + 0.5T). .25T is the pulse width of the same pulse. In addition, in the first measurement pulse train signal shown in FIGS. 2C and 2D, 4 is obtained by adding 0.25T, which is an advance of the rising timing of the pulse of the reproduction signal, to 4.5T (4T + 0.5T). .75T is the pulse width of the same pulse. The first measurement pulse train signal is output to the jitter measuring device 25.

  The second measurement pulse train signal generation circuit 24 generates a second measurement pulse train signal using the reference signal and the binarized reproduction signal. Specifically, as described above, a pulse train signal is generated that rises and synchronizes with the rising timing of the pulse of the reference signal and changes with the falling timing of the pulse of the reproduction signal. In this case, when the fall timing of the pulse of the reproduction signal is synchronized with the rise timing of the pulse of the clock signal, the pulse width of the pulse of the generated second measurement pulse train signal is the pulse of the corresponding reproduction signal. The pulse width is obtained by subtracting 0.5T from the signal length. This is because the rise timing of the pulse of the second measurement pulse train signal is synchronized with the rise timing of the reference signal delayed by 0.5T.

  On the other hand, when the fall timing of the pulse of the reproduction signal is not synchronized with the rise timing of the pulse of the clock signal, specifically, the fall timing of the pulse of the reproduction signal is advanced with respect to the rise timing of the clock signal. Alternatively, if it is delayed, the pulse width of the pulse of the second measurement pulse train signal to be generated is set to a pulse width obtained by subtracting 0.5T from the signal length of the pulse of the corresponding reproduction signal. The pulse width is obtained by increasing or decreasing the advance or delay of. For example, in the second measurement pulse train signal shown in FIGS. 2 (A) and 2 (C), 0.25T, which is the delay of the fall timing of the reproduction signal pulse, is changed to 3.5T (4T-0.5T). The added 3.75T is the pulse width of the same pulse. Also, in the second measurement pulse train signal shown in FIGS. 2B and 2D, 0.25T, which is the advance of the fall timing of the reproduction signal pulse, is changed from 3.5T (4T-0.5T). The reduced 3.25T becomes the pulse width of the same pulse. The second measurement pulse train signal is output to the jitter measuring device 25.

  The jitter measuring device 25 measures the jitter of each pulse of the binarized reproduction signal, the first measurement pulse train signal, and the second measurement pulse train signal, and outputs the measurement result to the computer device 30. In this case, the measured jitter is a pulse width distribution (variation) of each pulse in the reproduction signal, the first measurement pulse train signal, and the second measurement pulse train signal. The computer 30 displays the measurement results on the display device 32 for each signal length of the reproduction signal (3T to 11T for CD, 3T to 11T, 14T for DVD, 2T to 8T for Blu-ray Disc).

  Further, the computer device 30 causes the display device 32 to display the measurement result of each pulse of the first measurement pulse train signal for each signal length obtained by adding 0.5T to each signal length of the reproduction signal. This is because, as described above, the pulse width of the pulse of the first measurement pulse train signal is a pulse width obtained by adding 0.5T to the signal length of the pulse of the corresponding reproduction signal. Further, the computer device 30 causes the display device 32 to display the measurement result of each pulse of the second measurement pulse train signal for each signal length obtained by subtracting 0.5T from each signal length in the reproduction signal. This is because, as described above, the pulse width of the pulse of the second measurement pulse train signal is a pulse width obtained by subtracting 0.5T from the signal length of the pulse of the corresponding reproduction signal. 3A and 3B show display examples of the measurement results of the jitter of the first measurement pulse train signal and the second measurement pulse train signal. 3A shows the measurement results (3.5T to 8.5T) of the first measurement pulse train signal at signal lengths 3T to 8T in a frequency distribution, and FIG. 3B shows the signal lengths from 3T to 8T. The measurement result (2.5T-7.5T) of the 2nd pulse train signal for measurement is shown by frequency distribution.

  In the jitter measurement result of the first measurement pulse train signal shown in FIG. 3A, when the distribution center of the measurement result exists on the side where the signal length is small (the left side in the drawing) with respect to each signal length (signal length 3. 5T, 4.5T) indicates that the rising timing of the pulse of the reproduction signal is delayed with respect to the rising timing of the clock signal. In addition, when the distribution center of the measurement result is present on the longer signal length side (the right side in the figure) with respect to each signal length (signal length 7.5T, 8.5T), the rise timing of the pulse of the reproduced signal is It shows that the process is advanced with respect to the rising timing of the clock signal. On the other hand, in the jitter measurement result of the second measurement pulse train signal shown in FIG. 3B, when the distribution center of the measurement result is present on the smaller signal length side (left side in the figure) with respect to each signal length (signal length) 2.5T, 3.5T) indicates that the fall timing of the pulse of the reproduction signal is advanced with respect to the rise timing of the clock signal. In addition, when the distribution center of the measurement result for each signal length exists on the side where the signal length is large (the right side in the figure) (signal length 6.5T, 7.5T), the fall timing of the pulse of the reproduction signal Represents a delay with respect to the rising timing of the clock signal.

  Next, the operator operates the input device 31 on the basis of the measurement results of the jitters of the reproduction signal, the first measurement pulse train signal, and the second measurement pulse train signal displayed on the output device 32, and the optical pickup device. The strategy setting of the laser light emitted from the 12 laser light sources is corrected. Specifically, the operator first determines the variation in pulse width for each signal length and each of the signal lengths of the reproduction signal, the first measurement pulse train signal, and the second measurement pulse train signal. Check the phase shift for each signal length.

  Next, the operator determines the variation in the pulse width for each signal length and the phase for each signal length based on the jitter for each signal length of the reproduction signal, the first measurement pulse train signal, and the second measurement pulse train signal. Correct the deviation. In particular, it is a feature of the present invention that the phase shift for each signal length is corrected based on the jitter of the first measurement pulse train signal and the second measurement pulse train signal. In this case, specifically, the light quantity and position setting values of the specific pulse of the strategy mainly for the laser light emitted from the laser light source are corrected for each signal length. For example, when the rising timing of the pulse of the reproduction signal is delayed (signal lengths 3.5T and 4.5T shown in FIG. 3A), the initial light amount at the time of forming the recording marks having the signal lengths 3T and 4T. Is increased and / or corrected so that the position of the first pulse is shifted forward. Further, when the fall timing of the pulse of the reproduction signal is advanced (signal lengths 2.5T and 3.5T shown in FIG. 3B), the final stage when the recording marks having the signal lengths 3T and 4T are formed. Correction is made so that the amount of light is increased and / or the position of the last pulse is shifted backward. In addition to the light quantity and position of the specific pulse of the laser light strategy, each set value such as the number of pulses for each signal length of the laser light, the width of each pulse, the light quantity and the interval between the pulses is also corrected as appropriate. In some cases.

  The operation of correcting the strategy setting is instructed to the computer device 30 via the input device 31. In response to this instruction, the computer device 30 outputs a signal related to the strategy setting corresponding to the input correction amount to the strategy setting circuit 29. The strategy setting circuit 29 resets the strategy based on a signal related to the setting of the strategy and outputs it to the recording signal generation circuit 28.

  Next, the operator operates the input device 31 to instruct the computer device 30 to record inspection data on the optical disc DK again. In response to this instruction, the computer 30 records inspection data in a predetermined storage area of the optical disc DK in the same manner as described above. In this case, inspection data is recorded on the optical disc DK by laser light based on the reset strategy. Next, the operator operates the input device 31 to instruct the computer device 30 again to measure the jitter of the reproduction signal. In response to this instruction, the computer device 30 reproduces the inspection data recorded in the predetermined storage area of the optical disc DK in the same manner as described above to reproduce the reproduction signal, the first measurement pulse train signal, and the second measurement data. The jitter of the pulse train signal is measured. Then, the operator corrects the strategy setting as appropriate based on the measurement results of each jitter in the same manner as described above.

  The pulse width for each signal length in the reproduction signal is obtained by repeatedly performing such correction of the strategy, measurement of each jitter of the recording and reproduction signal for inspection, the first measurement pulse train signal, and the second measurement pulse train signal. And the phase shift for each signal length are eliminated, and an optimum strategy of the laser light emitted from the laser light source is set. In this state, the worker determines whether the optical disc DK is good or bad. Since the evaluation of the optical disk DK is not related to the present invention, the description thereof is omitted. When performing inspection of another optical disk DK, a new optical disk DK is placed and fixed on the turntable, and the inspection is performed in the same manner.

  As can be understood from the above description of operation, according to the above embodiment, the timing of one change is synchronized with the falling timing of the clock signal, and the timing of the other change is synchronized with the rising timing of the reproduction signal. Generating a measurement pulse train signal and a second measurement pulse train signal in which the timing of one change is synchronized with the falling timing of the clock signal and the timing of the other change is synchronized with the falling timing of the reproduction signal. Jitter of the first measurement pulse train signal and the second measurement pulse train signal is measured. In this case, the pulse width of the pulse of the reproduction signal is the same when the rising timing of the reproduction signal synchronized with the first measurement pulse train signal is synchronized with that when the reproduction signal is synchronized with the rising timing of the clock signal. However, the pulse width of the generated first measurement pulse train signal is different. The difference in the pulse width of the first measurement pulse train signal represents a phase shift in the rising timing of the reproduction signal that is not synchronized with the clock signal. Therefore, if the pulse width of the pulse of the first measurement pulse train signal is measured, that is, if the jitter is measured, it is possible to detect a phase shift of the rising timing of the reproduction signal. Similarly, by measuring the jitter of the second measurement pulse train signal, it is possible to detect a phase shift of the fall timing of the reproduction signal. Thereby, it is possible to set the strategy of the laser beam emitted from the laser light source in consideration of the phase shift of each pulse of the reproduction signal reproduced from the optical disc DK, and to improve the recording accuracy of the signal to the optical disc. Can do.

  Furthermore, in carrying out the present invention, the present invention is not limited to the above embodiment, and various modifications can be made without departing from the object of the present invention.

  In the above embodiment, the operator sets the strategy based on the jitter measurement result of each pulse train of the first measurement pulse train signal and the second measurement pulse train signal displayed on the output device 32. However, the present invention is not limited to this. For example, the strategy correction may be performed by the computer device 30 based on the jitter measurement result of each pulse of the first measurement pulse train signal and the second measurement pulse train signal by the jitter measuring device 25. In this case, the computer device 30 calculates the variation (standard deviation) amount of the pulse width for each signal length based on the measurement result of the jitter of the reproduced signal by the jitter measuring device 25, and the calculated variation (standard deviation). ) Using the quantity, calculate a correction value such as a strategy pulse waveform, that is, the number of pulses, the width of each pulse, the amount of light, and the interval between pulses. Further, the computer device 30 calculates a phase shift amount for each signal length based on the jitter measurement results of the first measurement pulse train signal and the second measurement pulse train signal, and calculates the calculated phase shift. The quantity is used to calculate the light quantity and position correction value of the specific pulse of the strategy. In this case, the relationship between each deviation amount and each correction value is obtained in advance by various experiments, and data representing the relationship is stored in the computer device 30 in advance. Then, the computer device 30 corrects the strategy set in the strategy setting circuit 29 based on the calculated pulse waveform of the strategy of the laser beam and the correction value of the light quantity and position of the specific pulse of the strategy. That's fine.

  Further, in the above embodiment, the reference signal for the portion corresponding to the portion where the recording mark is formed on the optical disk DK in the reproduction signal, that is, the low level signal (corresponding to the high level signal in the above embodiment), the first measurement signal Although the pulse train signal and the second measurement pulse train signal are generated and the laser light strategy is set based on the jitter of each signal, the present invention is not limited to this. For example, in addition to this, a reference signal, a first measurement pulse train signal, and a second measurement pulse train signal are similarly generated for the high level signal of the reproduction signal (corresponding to the low level signal in the above embodiment), and each signal is generated. It is possible to check whether or not the adjusted strategy was optimum for the high level signal of the reproduction signal (corresponding to the low level signal in the above embodiment). Thereby, the strategy of the laser beam can be set with higher accuracy.

  Further, in the above embodiment, the present invention is applied to the optical disk device for inspecting the optical disk DK, but the present invention records a signal on the optical disk DK or reproduces a signal recorded on the optical disk DK. The present invention can also be widely applied to the optical disk apparatus that performs the above.

1 is a block diagram schematically showing an optical disk inspection apparatus according to an embodiment of the present invention. (A)-(D) are time charts showing pulse waveforms of various signals generated in the optical disk inspection apparatus of FIG. (A), (B) is explanatory drawing which shows the measurement result of the jitter displayed on the output device of the inspection apparatus of the optical disk of FIG. 1 for every signal length. (A), (B) is explanatory drawing which shows the phase shift | offset | difference of the pulse of the reproduction | regeneration signal reproduced | regenerated from the optical disk in the optical disk apparatus by a prior art example.

Explanation of symbols

DK: optical disk, 12: optical pickup device, 14: reproduction signal generation circuit, 16: binarization circuit, 21: clock signal generation circuit, 22: reference signal generation circuit, 23: first measurement pulse train signal generation circuit, 24 ... second measurement pulse train signal generation circuit, 25 ... jitter measuring device, 29 ... strategy setting circuit, 30 ... computer device.

Claims (6)

Reproduction signal generating means for irradiating an optical disk with laser light emitted from a laser light source and generating a reproduction signal composed of a pulse train corresponding to data recorded on the optical disk using the laser light reflected by the optical disk In an optical disk device,
Clock signal generating means for generating a clock signal based on the reproduction signal;
The timing of one of the rising change and falling change is synchronized with the rising timing or falling timing of the clock signal generated by the clock signal generating means, and the other of the rising change and falling change is synchronized. First measurement pulse train signal generation means for generating a first measurement pulse train signal in which the timing of change is synchronized with the rise timing or fall timing of the reproduction signal;
An optical disc apparatus comprising: jitter measuring means for measuring jitter of the first measurement pulse train signal generated by the first measurement pulse train signal generating means. The optical disk apparatus according to claim 1, further comprising:
The timing of the other change of the rising change and the falling change is synchronized with the rising timing or falling timing of the clock signal generated by the clock signal generating means, and the rising change and falling change A second measurement pulse train signal generating means for generating a second measurement pulse train signal in which the timing of one change is synchronized with the rising timing or falling timing of the reproduction signal;
The jitter measuring means is an optical disc apparatus for measuring jitter of the second measurement pulse train signal in addition to the first measurement pulse train signal. The optical disc apparatus according to claim 1 or 2, further comprising:
An optical disk apparatus having a display device for displaying jitter measured by the jitter measuring means. The optical disc apparatus according to any one of claims 1 to 3, further comprising:
An optical disc apparatus comprising laser light correction means for correcting characteristics of laser light emitted from a laser light source based on jitter measured by the jitter measurement means when recording data on an optical disk. The present invention is applied to an optical disc apparatus that irradiates an optical disc with laser light emitted from a laser light source and generates a reproduction signal composed of a pulse train corresponding to data recorded on the optical disc using laser light reflected by the optical disc, In the phase shift detection method for detecting the phase shift of the reproduction signal,
A clock signal generating step for generating a clock signal based on the reproduction signal;
The timing of one of the rising change and falling change is synchronized with the rising timing or falling timing of the clock signal generated by the clock signal generating step, and the other of the rising change and falling change is synchronized. A first measurement pulse train signal generation step of generating a first measurement pulse train signal in which the timing of the change is synchronized with the rise timing or fall timing of the reproduction signal;
And a jitter measurement step of measuring a jitter of the first measurement pulse train signal generated by the first measurement pulse train signal generation step. The phase shift detection method according to claim 5, further comprising:
The timing of the other of the rising change and falling change is synchronized with the rising timing or falling timing of the clock signal generated by the clock signal generation step, and the rising change and falling change Including a second measurement pulse train signal generation step of generating a second measurement pulse train signal in which the timing of one change is synchronized with the rise timing or fall timing of the reproduction signal;
The jitter measurement step is a phase shift detection method for measuring jitter of the second measurement pulse train signal in addition to the first measurement pulse train signal.

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