JP2008071450A - Optical axis adjusting method for laser beam, deviation detecting device, and optical disk for adjusting optical axis - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical axis adjusting method for laser beam by which positions of a plurality of light spots on an optical disk can be matched more accurately with each other. <P>SOLUTION: A plurality of laser beams are projected to an optical disk DK0 for adjusting optical axis provided with an isolation track region I<SB>t</SB>and an isolation pit region I<SB>p</SB>. Since a tracking error signal caused when the light spot crosses the isolation track region I<SB>t</SB>can be distinguished from other tracking signals, a signal waveform of the tracking error signal caused by a plurality of light spots can be comprehended clearly. Therefore, diameter direction position deviation of the light spot is adjusted based on the tracking error signal waveform. Also, since a reproduced signal caused when the light spot crosses the isolation pit region I<SB>p</SB>can be distinguished from other reproduced signals, a signal waveform of the reproduced signal caused by a plurality of light spots can be comprehended clearly. Therefore, circumferential position deviation of the light spot is adjusted based on the reproduced signal waveform. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention is directed to a laser light irradiation apparatus that irradiates a same object such as the same optical disk with a plurality of laser beams and generates a signal based on reflected light from the same object. A method of adjusting the optical axes of a plurality of laser beams so that the positions of the light spots on the object of the plurality of laser beams irradiated on the object coincide with each other, and a signal evaluation device (formed on the same object) The present invention relates to an optical axis adjusting optical disc and an optical axis adjusting optical disc.

  In an optical disc apparatus that records data on an optical disc by irradiating the recording surface of the optical disc with laser light or reproduces data recorded on the optical disc, for example, a plurality of laser beams are emitted as in a collinear hologram recording / reproducing device. 2. Description of the Related Art An optical disc apparatus that irradiates an optical disc through a common objective lens and forms a light spot at the same position of the optical disc is known.

  In a collinear hologram recording / reproducing apparatus, a recording laser beam (information laser beam and a reference laser beam; hereinafter referred to as a recording laser beam) or a reproducing laser beam (hereinafter referred to as a recording laser beam and a reproducing laser beam). The laser beam for recording / reproduction (collectively referred to as laser beam for recording / reproducing) and the laser beam for servo for performing focus servo and tracking servo (hereinafter referred to as servo laser beam) are placed at the same position on the optical disk via the objective lens. Irradiate. For this reason, it is necessary to adjust the optical axis of each laser beam so that the position of the light spot of each laser beam on an optical disk may correspond.

A method of adjusting the optical axes of a plurality of laser beams so that the light spots of the plurality of laser beams coincide with each other is, for example, in Patent Document 1 that has not been disclosed at the time of filing this application, a recording / reproducing laser beam and a servo laser beam. Are independently incident on the autocollimator, and each laser beam is adjusted so as to be condensed at the center of the CCD in the autocollimator.
Japanese Patent Application No. 2005-343049

  In the optical axis adjustment method described in Patent Document 1, the optical axis is adjusted while an operator sees and confirms an image displayed on a display device based on a light reception signal output from a CCD in an autocollimator. In addition, the accuracy of adjustment is not high because of manual intervention. For this reason, a slight shift often occurs in the position of the light spot of each laser beam on the optical disk. The slight deviation increases the influence on recording / reproducing accuracy as the structure for recording / reproducing the optical disc becomes finer. Therefore, in an optical disc capable of performing high-density recording / reproduction, such as a hologram recording / reproduction optical disc using multiple light interference fringes, a slight deviation between the light spots of the recording / reproduction laser beam and the servo laser beam. Therefore, there is a problem that the accuracy of data recording and data reproduction deteriorates.

  The present invention has been made to address the above problems, and an object of the present invention is to provide a laser beam optical axis adjustment method capable of matching the positions of the light spots of a plurality of laser beams on an object with higher accuracy. There is. It is another object of the present invention to provide a deviation detecting device and an optical axis adjusting optical disc for detecting deviations of a plurality of light spots formed on the same object (optical disc) when adjusting the optical axis of laser light.

In order to achieve the above object, the features of the present invention are:
For a laser light irradiation apparatus that irradiates an optical disc with a plurality of laser beams to form a light spot on the optical disc and generates a signal by receiving reflected light from the optical disc irradiated with the plurality of laser beams An optical axis adjustment method for adjusting the optical axes of the plurality of laser beams so that the positions of the plurality of light spots formed on the optical disc coincide with each other,
An optical axis adjusting optical disc in which tracks are formed along a circumferential direction in at least a predetermined radial region and pits are formed in the track, and the optical axis adjusting optical disc has predetermined Rotating an optical disc having a track-free area formed over a radial width of the track and a pit-free area formed over a predetermined circumferential length on both sides of a predetermined pit or group of pits in at least one track A laser beam irradiation step of irradiating a plurality of laser beams so as to cross the predetermined track or group of tracks and pass through the predetermined pit or group of pits;
A signal generation step of detecting reflected light of the plurality of laser beams irradiated to the optical axis adjusting optical disc in the laser beam irradiation step for each of the plurality of laser beams, and generating a signal based on the reflected light, respectively;
A deviation detecting step of detecting deviations of a plurality of light spots formed on the optical axis adjusting optical disc based on the signal generated for each reflected light in the signal generating step;
An optical axis adjustment step of adjusting the optical axes of the plurality of laser beams based on the deviations of the plurality of light spots detected in the deviation detection step;
The optical axis adjustment method includes

  In this case, the deviation detection step detects deviations of a plurality of light spots formed on the optical axis adjustment optical disk based on the generation timing of the signal generated for each reflected light in the signal generation step. It should be a thing. The signal generating step includes a crossing signal generating step for generating a crossing signal generated when the light spots of the plurality of laser beams cross the predetermined track or group of tracks, and a light spot of the plurality of laser beams. And a passage signal generation step of generating a passage signal that is generated when passing through the predetermined pit or pit group. Here, the “shift of the light spot” includes a position shift of a plurality of light spots formed on the optical disc and any shift associated with the position shift. “Any shift due to a position shift” indicates, for example, a tracking error signal generated based on the reflected light of each light spot generated due to a position shift of a light spot, a time shift of a reproduction signal, or the like. .

  According to the above invention, a crossing signal (for example, tracking error) generated when a light spot crosses a predetermined track or a group of tracks (hereinafter referred to as an isolated track region) formed between non-track regions in an optical axis adjusting optical disk. The signal) can be distinguished from the crossing signal generated when the light spot crosses a track other than the isolated track region because both sides of the isolated track region are track-free regions and no track is formed. Therefore, it is possible to clearly grasp the generation timing of the crossing signal generated at this time. Therefore, a plurality of laser beams are irradiated on the optical axis adjusting optical disc, and a plurality of crossing signals generated when a plurality of light spots cross an isolated track region, and a plurality of light spots cross another track. The generation timing can be compared without being influenced by the crossing signal generated when Then, based on the comparison result, the optical axes of the plurality of laser beams are adjusted so that the radial positions of the light spots coincide.

  Further, a passing signal (for example, a reproduction signal) generated when a light spot passes through a predetermined pit or a group of pits (hereinafter referred to as an isolated pit area) formed between non-pit areas in a track of an optical axis adjusting optical disc is Since both sides of the isolated pit area are non-pit areas and no pits are formed, the light spot can be distinguished from a passing signal generated when passing through a pit other than the isolated pit area in the same track. it can. Therefore, it is possible to clearly grasp the generation timing of the passage signal generated at this time. Therefore, a plurality of laser beams are irradiated on the optical axis adjusting optical disk, and a plurality of light spots pass through other pits, while a plurality of light spots pass through the isolated pit region. The generation timing can be compared without being influenced by the passing signal that is sometimes generated. Then, based on the comparison result, the optical axes of the plurality of laser beams are adjusted so that the circumferential positions of the light spots coincide.

  As described above, the present invention divides the deviation of the plurality of light spots formed on the optical disc into the radial deviation and the circumferential deviation so that the positions of the light spots coincide with the deviations in the respective directions. The optical axis of the laser beam can be adjusted. Therefore, the positions of the light spots of the plurality of laser beams can be matched more accurately.

  In the above invention, the predetermined radial width and the predetermined circumferential length are such that a signal generated when a light spot crosses an isolated track area or passes through an isolated pit area is transmitted to another track. The width and length are such that they can be distinguished from signals generated when crossing or passing other pits.

  In addition, the optical axis adjusting step adjusts the optical axes of the plurality of laser beams based on the crossing signal so that the positions of the plurality of light spots in the radial direction of the optical disc coincide with each other. And a circumferential direction adjusting step of adjusting the optical axes of the plurality of laser beams so that the positions of the plurality of light spots in the circumferential direction of the optical disc coincide with each other based on the passing signal. According to this, the deviation of the radial positions of the plurality of light spots is adjusted in the radial adjustment step, and the deviation of the circumferential positions of the plurality of light spots is adjusted in the circumferential adjustment step. Thereby, the positions of a plurality of light spots can be completely matched. In the following description, “radial direction” indicates the radial direction of the optical disc on which the light spot is formed, and “circumferential direction” indicates the peripheral direction of the optical disc on which the light spot is formed.

  Further, the shift detection step may include a display step for displaying a plurality of signals generated in the signal generation step. According to this, in the display step, signals derived from the respective light spots generated in the signal generation step are displayed. Then, the deviation in the generation timing of each displayed signal represents the deviation in the position of each light spot. Therefore, in the optical axis adjustment step, the operator visually determines whether or not the positions of the light spots match by adjusting the optical axis of the laser beam so that the generation timings of the displayed signals match. be able to.

  The shift detection step includes a signal comparison step for comparing a plurality of signals generated for each reflected light in the signal generation step, and a shift amount of the plurality of light spots based on a comparison result in the signal comparison step. It is good also as what includes the deviation amount calculation step to calculate. According to this, the signals derived from the respective light spots are compared in the signal comparison step, and the deviation amount of each light spot can be detected in the deviation amount detection step based on the comparison result.

  At this time, the signal generation step includes a crossing signal generation step and a passing signal generation step. The crossing signal generation step generates a crossing signal, and the passing signal generation step generates a passing signal. A step of comparing a plurality of crossing signals generated in the crossing signal generation step, a crossing signal comparison step of comparing the plurality of crossing signals generated in the crossing signal generation step, and It is preferable to include a deviation amount calculating step for calculating the deviation amount based on the comparison results in the crossing signal comparison step and the passing signal comparison step. In this way, the amount of deviation of the light spot in the radial direction of the optical axis adjustment optical disk is calculated from the comparison result in the crossing signal comparison step, and the light spot in the circumferential direction of the optical axis adjustment optical disk is calculated from the comparison result in the pass signal comparison step. The amount of deviation is calculated. Furthermore, in this case, the deviation amount calculating step includes a radial direction deviation amount calculating step for calculating deviation amounts in the radial direction of a plurality of light spots based on the comparison result in the crossing signal comparison step, and a comparison in the passing signal comparison step. It is preferable to include a circumferential shift amount calculating step for calculating a shift amount in the circumferential direction of the plurality of light spots based on the result. According to this, the optical axis of the laser beam can be efficiently adjusted by independently adjusting the deviation amount in the radial direction and the deviation amount in the circumferential direction of the plurality of light spots.

  The deviation detection step includes: a crossing signal binarization step that binarizes the crossing signal generated in the crossing signal generation step into a pulse signal; and the passage signal generated in the passage signal generation step. And a passing signal binarizing step for binarizing into a pulse signal. In the crossing signal comparing step, the optical axis adjusting step is performed based on the pulse signal generated in the crossing signal binarizing step. A transverse signal evaluation pulse signal, which is a pulse signal indicating a positional shift of a plurality of light spots in the radial direction of the optical disc, is generated, and the passing signal comparison step includes the pulse signal generated in the passing signal binarization step. On the basis of the pass signal evaluation pulse, which is a pulse signal indicating the positional deviation of the plurality of light spots in the circumferential direction of the optical axis adjusting optical disk Generates a signal, the shift amount calculation step, based on said crossing signal evaluation pulse signal and the passage signal evaluation pulse signal, or equal to those for calculating the shift amount. According to this, since the signals indicating the radial and circumferential deviations of the plurality of light spots are output as pulse signals, the degree of deviation can be quantified (quantified). Therefore, it is possible to grasp the amount of deviation quantitatively and to recognize that the optical axis of the laser beam has been adjusted by setting the numerical value indicating the deviation amount to zero.

  When generating a pulse signal for crossing signal evaluation and / or a pulse signal for passing signal evaluation, a plurality of pulse signals of various patterns are generated, and a pulse signal for crossing signal evaluation or a pulse signal for passing signal evaluation is generated from them. There may be provided a selection step for selecting. Since the evaluation pulse signal is generated based on a plurality of input pulse signals, a plurality of patterns of pulse signals can be generated from these pulse signals. By imposing a predetermined condition from these and setting the pulse signal that matches the condition as the evaluation pulse signal, an accurate evaluation pulse signal can be obtained.

  In this case, the deviation detection step includes a line that specifies a linear velocity of a light spot formed on the optical axis adjustment optical disc with respect to the optical axis adjustment optical disc when the optical axis adjustment optical disc is rotating. A speed specifying step, and an inter-track crossing time detecting step for detecting a time during which the light spot crosses from the predetermined track or track group to an adjacent track or track group, and the deviation amount calculating step includes: The pulse width of the first evaluation pulse signal, the pulse width of the second evaluation pulse signal, the linear velocity specified in the linear velocity specifying step, and the track interval detected in the inter-track crossing time detection step Based on the crossing time, the shift amount of the position of the plurality of light spots on the optical disk is calculated. When may. According to this, since the deviation of the light spot represented by the first evaluation pulse signal and the second evaluation pulse signal is often a deviation expressed in units of time, as in the present invention, By taking into consideration the linear velocity and the crossing time between the tracks, the deviation of the position of the light spot can be calculated in units of length. Therefore, it can be grasped specifically how much the light spot is shifted.

Another feature of the present invention is that
For a laser light irradiation apparatus that irradiates an optical disc with a plurality of laser beams to form a light spot on the optical disc and generates a signal by receiving reflected light from the optical disc irradiated with the plurality of laser beams In the deviation detection device for detecting deviations of a plurality of light spots formed on the optical disc,
A first pulse signal generating means for generating a first pulse signal by inputting a signal based on reflected light from a first light spot formed on the optical disc and binarizing the input signal;
A second pulse signal generating means for generating a second pulse signal by inputting a signal based on the reflected light from the second light spot formed on the optical disc and binarizing the input signal;
The first pulse signal and the second pulse signal are input, and the first pulse signal and the second pulse signal cause a positional deviation between the first light spot and the second light spot. An evaluation pulse signal generating means for generating an evaluation pulse signal that becomes a high level or a low level when the predetermined relationship is expressed and becomes a low level or a high level when the relationship is other than the predetermined relationship;
Pulse width measuring means for measuring the pulse width of the high level portion or the low level portion of the pulse signal for evaluation;
The deviation detecting device is configured as comprising the above.

  According to the above invention, when signals (for example, tracking error signals and reproduction signals) based on reflected light from a plurality of light spots formed on the optical disc are input to the shift detection device, these signals are output as the first pulse. It is converted into a binarized pulse signal by the signal generating means and the second pulse signal generating means. The converted pulse signal is input to the evaluation pulse signal generation means. At this time, if at least two pulse signals generated by the first and second pulse signal generation means are shifted in time and input to the evaluation pulse signal generation means, generation of an evaluation pulse signal indicating the time shift is generated. Is possible. If the input pulse signals have the same waveform, this deviation can be grasped from the timing when each pulse signal rises at the high level or at the low level, or the input pulse signal If it changes with time, it can also be grasped from its shape comparison. In this way, the evaluation pulse signal generation means generates a pulse signal in which the amount of deviation resulting from the positional deviation of the light spot is represented by the pulse width of the high level section or the pulse width of the low level section. Then, the pulse width measuring means measures the pulse width of the high level section or the pulse width of the low level section indicating the portion representing the shift, and measures the shift amount of the plurality of light spots. In this case, as described above, the pulse width of the evaluation pulse signal often represents a time lag between a plurality of light spots. Therefore, by obtaining the circumferential speed and radial speed of the optical disk and multiplying the obtained speed by the time measured as the pulse width, the positional deviation amounts of the plurality of light spots can be obtained. This deviation detection device is suitable for use in the optical axis adjustment method described above.

  In the above, the “signal based on reflected light” is a signal in which the characteristics of reflected light such as the intensity of reflected light of the light spot change as the optical disk rotates when the light spot is formed on the optical disk. It is. This signal can be a tracking error signal generated when the light spot crosses a track of the optical disk, or a reproduction signal generated when the light spot passes through a pit or mark. In this case, if both the tracking error signal and the reproduction signal are used as the “signal based on the reflected light”, the deviation in the radial direction of the light spot is detected based on the tracking error signal, and the light is detected based on the reproduction signal. A deviation in the circumferential direction of the spot is detected.

Another feature of the present invention is that
For a laser light irradiation apparatus that irradiates an optical disc with a plurality of laser beams to form a light spot on the optical disc and generates a signal by receiving reflected light from the optical disc irradiated with the plurality of laser beams An optical axis adjusting optical disc for adjusting optical axes of the plurality of laser beams so that positions of a plurality of light spots formed on the optical disc coincide with each other,
An optical axis adjusting optical disc in which tracks are formed along a circumferential direction in at least a predetermined radial region and pits are formed in the track, and the optical axis adjusting optical disc has predetermined A track-free region formed across the radial width of
A non-pit area formed over a predetermined circumferential length on both sides in a circumferential direction of a predetermined pit or pit group in at least one track;
The optical axis adjusting optical disc is formed.

  The optical axis adjusting optical disk described above includes an isolated track area in which track-free areas are formed on both sides in the radial direction, and an isolated pit area in which no pit areas are formed on both sides in the circumferential direction. Therefore, the tracking error signal generated when the light spot crosses the isolated track region can be distinguished from the tracking error signal generated when the light spot crosses another track. Therefore, when comparing the deviation of a plurality of light spots, only the tracking error signal at the time of traversing the target track can be detected, so that the deviation in the radial direction of the plurality of light spots can be easily detected. . Similarly, a reproduction signal generated when a light spot passes through an isolated pit region can be distinguished from a reproduction signal generated when a light spot passes through another pit. Therefore, when comparing the deviation of a plurality of light spots, only the reproduction signal when passing through the target pit can be detected, and the deviation in the circumferential direction of the plurality of light spots can be easily detected. Such an optical axis adjusting optical disc is suitable for use in the above-described optical axis adjusting method.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described. FIG. 1 is a schematic diagram illustrating a state in which a signal evaluation apparatus 300 is connected to the laser beam irradiation apparatus 1 according to the present embodiment. The laser beam irradiation apparatus 1 irradiates a plurality of laser beams such as a recording / reproducing laser beam and a servo laser beam to the same position of an optical disc through a common objective lens like a collinear hologram recording / reproducing device. . The laser light irradiation device 1 includes a rotation driving device 50 that rotationally drives an optical disk DK, and an optical pickup device PUH that irradiates the optical disk DK with laser light and receives reflected light from the optical disk DK.

  The rotation drive device 50 includes a spindle motor 501 and a feed motor 503. The spindle motor 501 rotates the rotary shaft 501b by the rotation to rotate the turntable 505. An optical disk DK is detachably assembled to the top surface of the turntable 505. An encoder 501a is incorporated in the spindle motor 501, and the encoder 501a detects the rotation of the spindle motor 501, and outputs a rotation detection signal indicating the rotation to the spindle motor control circuit 502. The spindle motor control circuit 502 is controlled by the controller 600 described later, and controls the rotation of the spindle motor 501 so that the spindle motor 501 rotates at the rotation speed indicated by the controller 600 using the rotation detection signal supplied from the encoder 501a. . As a result, the optical disk DK is controlled to always rotate at a constant linear velocity. This linear velocity is stored in the controller 600 as linear velocity specifying means. The feed motor 503 rotates the spindle motor 501, a support member 507 for fixing and supporting the spindle motor 501 and a turntable 505 through a screw feed mechanism including a screw rod 506 and a nut (not shown) by the rotation of the feed motor 503. Displace in the direction.

  An encoder 503 a is also incorporated in the feed motor 503. The encoder 503a is configured in the same manner as the encoder 501a, detects the rotation of the feed motor 503, and outputs a rotation detection signal representing the rotation to the feed motor control circuit 504. The feed motor control circuit 504 inputs and stores an instruction of the radial position from the controller 600, calculates the radial position using the rotation detection signal output from the encoder 503a, controls the rotation of the feed motor 503, The position of the spindle motor 501, the turntable 505, and the support member 507 in the radial direction of the optical disk DK, that is, the position of the light spot within the range of the innermost circumference and the outermost circumference of the optical disk DK is controlled. Further, the feed motor control circuit 504 outputs information indicating the radial position of the light spot on the optical disc DK calculated using the rotation detection signal output from the encoder 503a to the controller 600.

  The optical pickup device PUH includes a first laser light source 401 and a second laser light source 402. The first laser light source 401 emits recording / reproducing laser light. In the present embodiment, the recording / reproducing laser beam is composed of a laser beam including information to be recorded (information laser beam) and a laser beam not including information (reference beam) at the time of recording. Further, at the time of reproduction, the laser light is only the reference light. When holographic recording is actually performed using these lasers, interference fringes are generated by causing information laser light and reference light to interfere with each other on the optical disc, and the interference fringes are recorded on the optical disc. When reproducing, the reference light is irradiated onto the optical disc DK on which the interference fringes are formed, and the recorded information is reproduced by diffraction from the interference fringes. The second laser light source 402 emits servo laser light for use in focus servo and tracking servo.

  The optical pickup device PUH includes an objective lens 403. The objective lens 403 is a lens used to focus the laser light from the first laser light source 401 or the second laser light source 402 on the optical disc DK. A first collimating lens 404, a half mirror 405, and a dichroic mirror 406 are disposed between the first laser light source 401 and the objective lens 403. Laser light emitted from the first laser light source 401 enters the optical disk DK via the first collimating lens 404, the half mirror 405, the dichroic mirror 406, and the objective lens 403. Between the second laser light source 402 and the objective lens 403, a second collimating lens 407, a polarizing beam splitter 408, a quarter wave plate 416, and a dichroic mirror 406 are disposed. Laser light emitted from the second laser light source 402 is incident on the optical disc through the second collimating lens 407, the polarization beam splitter 408, the quarter-wave plate 416, the dichroic mirror 406, and the objective lens 403.

  The laser beam reflected by the optical disk and directed from the dichroic mirror 406 side toward the half mirror 405 is partially reflected by the half mirror 405, passes through the convex lens 409, and is guided to the first photodetector 410. Is received. Further, the laser light that passes through the quarter-wave plate 416 from the dichroic mirror 406 side and travels toward the polarization beam splitter 408 is reflected by the polarization beam splitter 408, passes through the convex lens 411 and the cylindrical lens 412, and is second. The light is guided to the photodetector 413 and received by the second photodetector 413.

  The first photodetector 410 includes a light receiving element such as a CCD, and each pixel outputs a detection signal proportional to the amount of received light as a light receiving signal. The second photodetector 413 is a four-divided photodetector, which is composed of four light receiving elements having the same square shape divided by dividing lines. Each light receiving element receives a detection signal proportional to the amount of received light (A, B, C, D). ). The signals output from the pixels of the first photodetector 410 are summed and amplified in the same area as the four-divided areas of the second photodetector 413 in the first signal amplification circuit 120 described later, and the received light signals (A, A, B, C, D). Therefore, both the first photo detector 410 and the second photo detector 413 may be regarded as outputting light reception signals (A, B, C, D) from the quadrant photo detector.

  The optical pickup device PUH includes a tracking actuator 414 and a focus actuator 415. The tracking actuator 414 finely moves the objective lens 403 in the radial direction of the optical disk DK (or an optical axis adjusting optical disk DK0 described later), and a light spot of laser light irradiated on the optical disk DK is formed on the optical disk DK. This is an actuator for accurately positioning at the center of the track. The focus actuator 415 is an actuator for finely moving the objective lens 403 in a direction perpendicular to the laser light irradiation surface of the optical disk DK to focus the laser light on the recording surface of the optical disk DK.

  In addition to the above, the optical pickup device PUH includes an optical component for branching the recording / reproducing laser beam into the information laser beam and the reference beam, and for aligning the optical axes of the information laser beam and the reference beam. An optical component and a spatial light modulator (SLM) for providing information to laser light emitted from the first laser light source 401 to provide information are provided. Is not directly related to the pickup apparatus PUH in FIG.

  The light reception signal output from the first photodetector 410 is input to the first signal amplification circuit 120. The amplified signal output from the first signal amplifier circuit 120 is input to the first tracking error signal generation circuit 122 and the first reproduction signal generation circuit 124. The received light signal output from the second photodetector 413 is input to the second signal amplifier circuit 102. The amplified signal output from the second signal amplifier circuit 102 is input to the focus error signal generation circuit 104, the second tracking error signal generation circuit 110, and the second reproduction signal generation circuit 116. Signals output from the first tracking error signal generation circuit 122, the first reproduction signal generation circuit 124, the second tracking error signal generation circuit 110, and the second reproduction signal generation circuit 116 are input to the signal evaluation apparatus 300. A signal output from the focus error signal generation circuit 104 is input to the focus servo circuit 106. The focus servo circuit 106 controls driving of the focus actuator 415 via the focus actuator drive circuit 108. The signal output from the second tracking error signal generation circuit 110 is also input to the tracking servo circuit 112. The tracking servo circuit 112 controls driving of the tracking actuator 414 via the tracking actuator drive circuit 114.

  The controller 600 is constituted by a microcomputer including a CPU, ROM, RAM, hard disk, and the like, and a laser that irradiates the optical disk DK by executing the program of FIG. The light is controlled, and the control result is appropriately displayed on a display device 602 including an evaluation CRT (or liquid crystal display), a printer, and the like, and is output to the signal evaluation device 300. The controller 600 is connected to a feed motor control circuit 504, a spindle motor control circuit 502, a recording / reproducing laser drive circuit 202, and a servo laser drive circuit 200. The recording / reproducing laser drive circuit 202 controls the emission of the laser light from the first laser light source 401 in accordance with an instruction from the controller 600. The servo laser drive circuit 200 controls the emission of the laser light from the second laser light source 402 according to an instruction from the controller 600.

  In the laser beam irradiation apparatus 1 having the above configuration, first, at least one of the laser beam emitted from the first laser light source 401 and the laser beam emitted from the second laser light source 402 using an autocollimator (not shown). The optical axis of the laser beam is adjusted to adjust the optical axis of the laser beam to the optimum position. Thereafter, the optical axis adjusting optical disk DK0 is mounted on the turntable 505, and the optical axes of the plurality of laser beams are adjusted by the optical axis adjustment according to the present embodiment so that the positions of the light spots on the optical disk coincide. At this time, if there is one laser beam whose optical axis is adjusted by the autocollimator, the optical axis of the other laser beam is adjusted so that the position of the optical spot of the other laser beam is aligned with the position of the optical spot of the laser beam. . In addition, when the optical axes of both laser beams are adjusted by the autocollimator, the optical axis of either laser beam may be adjusted by adjusting the optical axis according to the present embodiment. As a reference, the optical axis of the other laser beam is adjusted so that the positions of both light spots are aligned.

  An optical axis adjusting optical disk DK0 used in this embodiment is shown in FIG. FIGS. 3 and 4 are schematic views showing the formation state of the tracks formed on the laser light irradiation surface of the optical disk DK0 and the arrangement state of the pits in the tracks. 3 and 4, the vertical direction in the figure indicates the radial direction of the optical disk DK0, and the horizontal direction in the figure indicates the circumferential direction of the optical disk DK0. The optical axis adjusting optical disk DK0 shown in FIG. 2 is the same size as a normal optical disk, and is a disk in which tracks (grooves) having the same width as the normal optical disk are formed along the circumferential direction. With the characteristics of.

- distance of the track T (distance between adjacent grooves) is sufficiently larger portion than the width D _T of the track T (groove) (Fig. 3, the region A portion in FIG. 4, hereinafter, this region of non-track area. A track or a group of tracks sandwiched between adjacent non-track areas is called an isolated track area.) In order to facilitate the adjustment work, it is desirable to have such a track-free region for every one to several tracks T (grooves). Further, as shown in FIG. 4, it is most desirable that a track-free region is formed for each track T (groove). The width of each track in the isolated track area can be made equal to the standard of an ordinary optical disc. The radial width of the track-free region can be, for example, 3 to 10 times the width of each track in the isolated track region.
The track T (groove) has an interval between the pit P (or mark) and the pit P (or mark) or an interval between the pit group (or mark group) and the pit group (or mark group). There is a portion that is formed to be sufficiently wider than the length of the mark (region B in FIGS. 3 and 4; hereinafter, this region is referred to as a non-pit region) and is sandwiched between adjacent non-pit regions. A pit or group of pits is called an isolated pit area.) In order to facilitate the adjustment work, the pit group or mark group is preferably one to several pits or marks. The individual pits or marks in the isolated pit area and the length between them can be equivalent to the standard of an ordinary optical disc. The circumferential length of the non-pit area can be, for example, 3 to 10 times the length of each pit or mark in the isolated pit area.

Although not always necessary, the optical axis adjusting optical disk DK0 may have the following structural features.
The track T (groove) is not spiral, but returns to its original position after one rotation (if it is spiral, servo control becomes unstable at locations where the track interval is wide).
The track T (groove) is formed only at a predetermined radial position on the optical axis adjusting optical disk DK0 (adjustment is possible even if it is formed over the entire radial direction, but a special disk Therefore, the larger the number of tracks, the higher the manufacturing cost of the optical axis adjusting optical disk).

Accordingly, the optical axis adjusting optical disc DK0 used in the present embodiment, in the radial direction on both sides of the isolated track area I _t, and no track region A formed over a predetermined radial width D _A, at least one track both sides in the circumferential direction of the isolated pit area I _p in the T, and a non-pit area B formed over the predetermined circumferential length D _B.

  The operator sets the optical axis adjusting optical disk DK0 described above on the turntable 505 of the laser light irradiation apparatus 1 shown in FIG. 1, and then connects the signal evaluation apparatus 300 to the laser light irradiation apparatus 1. This signal evaluation apparatus 300 is based on the reproduction signal (first reproduction signal) input from the first reproduction signal generation circuit 124 and the reproduction signal (second reproduction signal) input from the second reproduction signal generation circuit 116. The generation timing of a signal indicating that the pit P or mark formed on the track of the optical axis adjusting optical disk DK0 is irradiated with the laser beam is detected. The signal evaluation apparatus 300 also includes a tracking error signal (first tracking error signal) input from the first tracking error signal generation circuit 122 and a tracking error signal (second tracking error signal) input from the second tracking error signal generation circuit 110. Based on the error signal), the generation timing of a signal indicating that the laser beam has traversed the track T of the optical axis adjusting optical disk DK0 is detected.

  In this embodiment, a digital oscilloscope is used as the signal evaluation device 300. Therefore, the operator can reproduce the reproduction signal and the tracking error signal generation circuit (first tracking error signal) output from the reproduction signal generation circuit (first reproduction signal generation circuit 124 and second reproduction signal generation circuit 116) of the laser beam irradiation apparatus 1. The tracking error signals output from the generation circuit 122 and the second tracking error signal generation circuit 110) are input to predetermined terminals of a digital oscilloscope as the signal evaluation device 300. And the laser beam irradiation apparatus 1 is started, the input device 604 is operated, and the signal evaluation program shown in FIG. 5 is performed.

The signal evaluation program is started in step S100 of FIG. 5, and the controller 600 outputs a control command to the feed motor control circuit 504 in step S102. Upon receiving this control command, the feed motor control circuit 504 feeds the laser light from the first laser light source 401 and the second laser light source 402 to a predetermined radial direction position of the optical axis adjusting optical disk DK0. Is controlled to move the turntable 505. In this case, to move the turntable 505 such that the radial position of the laser beam is irradiated to the isolated track area I _t of the optical axis adjusting optical disc DK0 from the laser beam emitting device 1. Next, in step S <b> 104, the controller 600 outputs a control command to the spindle motor control circuit 502. Upon receiving this control command, the spindle motor control circuit 502 controls the spindle motor 501 so that the optical axis adjusting optical disk DK0 rotates on the turntable 505 at a predetermined linear velocity. The predetermined linear velocity at this time is stored in the controller 600 (linear velocity specifying step).

  Next, the controller 600 outputs a command to start driving to the servo laser driving circuit 200 in step S106. As a result, servo laser light is emitted from the second laser light source 402 (laser light irradiation step). The servo laser light is converted into parallel light by passing through the second collimating lens 407, and then enters the polarization beam splitter 408 and is mostly transmitted. The laser light transmitted through the polarizing beam splitter 408 passes through the quarter-wave plate 416 and enters the dichroic mirror 406, and is reflected by the dichroic mirror 406. The laser beam reflected by the dichroic mirror 406 is irradiated to the optical axis adjustment optical disk DK0 through the objective lens 403, and forms a light spot on the optical axis adjustment optical disk DK0.

  The reflected light of the servo laser light irradiated on the optical axis adjusting optical disk DK0 enters the dichroic mirror 406 through the objective lens 403, is reflected by the dichroic mirror 406, and further passes through the quarter-wave plate 416. Passes and enters the polarization beam splitter 408. The reflected light incident on the polarization beam splitter 408 from the dichroic mirror 406 side has been reflected by the polarization beam splitter 408 because the polarization direction has changed by 90 degrees because it has passed through the quarter-wave plate 416 twice. The reflected light is received by the second photodetector 413 through the convex lens 411 and the cylindrical lens 412.

  As described above, the second photodetector 413 is a four-divided photodetector, and each light receiving element of the second photodetector 413 uses the electrical signals A2, B2, C2, and D2 proportional to the amount of received light as received light signals to the second signal amplification circuit 102, respectively. Output. The second signal amplifying circuit 102 amplifies the received light signals A2 to D2 of the reflected light of the servo laser light output from the second photodetector 413, respectively, so that the focus error signal generating circuit 104 and the second tracking error signal generating circuit 110 are amplified. And output to the second reproduction signal generation circuit 116.

  The focus error signal generation circuit 104 generates a focus error signal ((A2 + B2) − (C2 + D2)) by the astigmatism method using the amplified received light signals A2 to D2, and the generated focus error signal is sent to the focus servo circuit 106. Output. The second tracking error signal generation circuit 110 generates a tracking error signal ((A2 + C2)-(B2 + D2)) by calculation in the case of the push-pull method using the amplified received light signals A2 to D2 (signal generation step, crossing signal). Generation step), and outputs the generated tracking error signal to the tracking servo circuit 112. The second reproduction signal generation circuit 116 generates a reproduction signal (SUM signal: A2 + B2 + C2 + D2) by an operation of totaling the amplified light reception signals A2 to D2 (signal generation step, pass signal generation step), and performs signal evaluation on the generated reproduction signal Output to the device 300.

  Subsequently, the controller 600 outputs a command to start driving to the recording / reproducing laser driving circuit 202 in step S108. Thereby, the recording / reproducing laser beam is emitted from the first laser light source 401 (laser beam irradiation step). The recording / reproducing laser light is converted into parallel light by passing through the first collimating lens 404, and then enters the half mirror 405 and partially transmits. The laser light partially transmitted through the half mirror 405 enters the dichroic mirror 406 and passes through the dichroic mirror 406. The laser light transmitted through the dichroic mirror 406 is irradiated onto the optical axis adjustment optical disk DK0 through the objective lens 403, and forms a light spot on the optical axis adjustment optical disk DK0.

  The reflected light of the recording / reproducing laser beam irradiated on the optical axis adjusting optical disk DK 0 is incident on the dichroic mirror 406 through the objective lens 403 and passes through the dichroic mirror 406. The reflected light that has passed through the dichroic mirror 406 further enters the half mirror 405 and is partially reflected by the half mirror 405. The reflected light partially reflected by the half mirror 405 is received by the first photodetector 410 through the convex lens 409.

  The first photodetector 410 is a photodetector made up of a light receiving element such as a CCD. As described above, the signals output from the respective pixels for each of the four divided areas of the first photodetector 410 are summed by the first signal amplification circuit 120 and amplified. Then, the received light signals A1, B1, C1, and D1 are output to the first tracking error signal generation circuit 122 and the first reproduction signal generation circuit 124.

  The first tracking error signal generation circuit 122 generates a tracking error signal ((A1 + C1) − (B1 + D1)) by the calculation in the push-pull method using the amplified received light signals A1 to D1 (signal generation step, crossing signal). Generation step), and outputs the generated tracking error signal to a digital oscilloscope as the signal evaluation apparatus 300. The first reproduction signal generation circuit 124 generates a reproduction signal (SUM signal: A1 + B1 + C1 + D1) by a calculation that adds up the amplified light reception signals A1 to D1 (signal generation step, pass signal generation step), and performs signal evaluation on the generated reproduction signal Output to the device 300.

  Next, the controller 600 starts focus servo in step S110 and performs focus pull-in. In step S110, the focus servo circuit 106 outputs a control signal for the focus actuator 415 to the focus actuator drive circuit 108 based on the focus error signal input from the focus error signal generation circuit 104. For this reason, the focus actuator drive circuit 108 drives and controls the focus actuator 415 so that the recording / reproducing laser beam and the servo laser beam are focused on the recording surface of the optical axis adjusting optical disc DK0. Position control in the direction perpendicular to DK0 is performed.

  Subsequently, in step S112, the controller 600 causes the display device 602 to display the adjustment direction input request. This input request is left to the operator to select whether the optical axis adjustment to be performed is optical axis adjustment in the radial direction of the optical disc DK0, optical axis adjustment in the circumferential direction, or adjustment is to be ended. Therefore, the terms or designs of “radial direction”, “circumferential direction”, and “end” are displayed on the display device for instructions from the operator. In response to the input request displayed on the display device 602, the operator selects whether the optical axis adjustment is performed in the radial direction, the circumferential direction, or the end of the optical axis adjustment optical disk DK 0, and is finished through the input device 604. input. Next, in step S114, the controller 600 determines whether or not the adjustment direction input from the worker in response to the input request in step S112 is the “radial direction”. When it is “radial direction”, the process proceeds to step S116, and when it is not “radial direction”, the process proceeds to step S120.

When the determination result in step S114 is Yes (the operator selects the optical axis adjustment in the radial direction) and the process proceeds to step S116, the controller 600 adds the digital oscilloscope serving as the signal evaluation apparatus 300 to the digital oscilloscope. The tracking error signal generated by the one tracking error signal generation circuit 122 and the tracking error signal generated by the second tracking error signal generation circuit 110 are displayed. At this time, since the tracking servo control is not performed, the recording / reproducing laser beam and the servo laser beam are affected by the eccentricity of the optical axis adjusting optical disk DK0, and the diameter thereof is smaller than that of the optical axis adjusting optical disk DK0. Relative displacement in the direction. As described above, the light spots of the two laser beams, the radial position so as to pass through the isolated track area I _t which is formed in the optical axis adjusting optical disc DK0 is adjusted by the feed motor control circuit 504.

At this time, when the light spot crosses the isolated track area I _t, the tracking error signal TE1 of the light spot of the first tracking error signal generating circuit 122 for recording and reproducing laser light generated by, and the second tracking error signal A tracking error signal TE2 of the light spot of the servo laser light generated by the generation circuit 110 is generated. Further, when the positions of both the light spots are shifted in the radial direction of the optical axis adjusting optical disk DK0, the generation timings of the tracking error signals TE1 and TE2 are also shifted. If the generation timings of both tracking error signals TE1 and TE2 can be matched, the positional deviation in the radial direction of both laser beams can be corrected.

  In this case, if the interval between the tracks formed on the optical disc is narrow, tracking error signals are continuously generated, and it is difficult to determine which tracking error signal waveform is a waveform when crossing a predetermined track. Therefore, when a conventional optical disk is used, the tracking error signal cannot be determined.

In contrast, the optical axis adjusting optical disc DK0 of this embodiment is provided with an isolated track area I _t, radial sides of the isolated track area I _t has a non-track area. Therefore, a tracking error signal generated when the light spot traverses the isolated track area I _t can be distinguished from other tracking error signals. Further, even when the isolated track area I _t as in FIG. 3 is formed by a plurality of tracks, both sides in the radial direction of the isolated track area I _t is if turned free track area, a plurality of tracking light spots isolated track region I _t which is formed by the track tracking error signal generated when crossing the which can be distinguished from other tracking error signal, corresponding to each track in the isolated track area I _t An error signal can also be determined by counting the number of signals.

Thus, the digital oscilloscope as a signal evaluation device 300, a tracking error signal TE1 to the light spot of the reproducing laser light is generated when crossing the isolated track area I _t, the light spot of the servo laser beam is the orphan it is possible to display only the tracking error signal TE2 generated when crossing a track area and the same isolated track area I _t (display step, the deviation detection step). When the light spot is deviated in the radial direction, the generation timing of both tracking error signals is deviated, so that both tracking error signals are displayed deviated. Therefore, by matching the generation timing based on the generation timing of the tracking error signal, the radial positions of the light spots can be matched.

In particular, as shown in FIG. 4, when the isolated track area I _t on the optical axis adjusting optical disc DK0 is formed with a single track, the light spot from one of the non-track region (region A portion) when across the isolated track I _t fall other free track region (region a section), as shown in FIG. 6, one of the tracking error signal TE1 of the light spot of the recording reproducing laser beam and the servo laser beam One tracking error signal TE2 of the light spot is projected on the digital oscilloscope. Therefore, it is convenient for comparing both tracking error signals TE1 and TE2.

  When the tracking error signal displayed on the digital oscilloscope is in the state shown in FIG. 6, the operator can select either the laser light emitted from the first laser light source 401 or the laser light emitted from the second laser light source 402. The optical axis of one of the laser beams is adjusted so that the zero cross points of the tracking error signals TE1 and TE2 coincide (optical axis adjustment step, radial direction adjustment step). By this adjustment operation, the radial positions of the light spots of the recording / reproducing laser beam and the servo laser beam can be matched. Although the radial position of both light spots may be shifted again by adjusting the circumferential direction described later, the radial position of both spots can be almost completely matched by adjusting many times. In the above adjustment, as shown in FIG. 6, when the adjustment is performed by aligning the cursor Cur in the vertical direction with the zero-cross point of the tracking error signal waveform, the degree of deviation is known and the adjustment is easy.

  After displaying the first tracking error signal TE1 and the second tracking error signal TE2 on the digital oscilloscope in step S116, the controller 600 determines whether or not the operator has performed an input operation indicating that the optical axis adjustment has been completed in step S118. judge. When the optical axis adjustment for matching the radial positions of the two light spots is completed, the operator performs an input operation to the effect that the optical axis adjustment is completed on the input device 604. Then, the controller 600 returns to step S112 to display the adjustment direction input request again on the display device 602. Since the optical axis adjustment in the radial direction of the optical axis adjustment optical disk DK0 is once completed as described above, the operator next adjusts the optical axis for making the optical spot coincide with the circumferential direction of the optical axis adjustment optical disk DK0. Therefore, the controller 600 inputs to the controller 600 via the input device 604 that the adjustment direction is the “circumferential direction”. Then, the determination in the next step S114 is No, and the process proceeds to step S120. In this step S120, it is determined whether or not there is an input to “end” the adjustment. When the input in the “circumferential direction” is performed, the determination in this step is No, and the process proceeds to step S122.

  In step S122, the controller 600 outputs a command to start tracking servo control. Accordingly, the tracking servo circuit 112 drives and controls the tracking actuator 414 via the tracking actuator drive circuit 114 based on the second tracking error signal generated by the second tracking error signal generation circuit 110. For this reason, the objective lens 403 slightly moves so that the light spot of the servo laser light follows the track T formed on the optical axis adjusting optical disk DK0. At this time, if the radial position of the optical spot of the recording / reproducing laser beam coincides with the radial position of the optical spot of the servo laser beam, the optical spot of the recording / reproducing laser beam is also the light of the servo laser beam. Track T along with the spot.

  Next, in step S124, the controller 600 causes the digital oscilloscope to display the reproduction signal generated by the first reproduction signal generation circuit 124 and the reproduction signal generated by the second reproduction signal generation circuit 116 (display step). , Deviation detection step). In this case, since the tracking servo control is performed in step S122, the recording / reproducing laser beam and the servo laser beam are irradiated onto the optical disc DK0 so as to follow the track.

When the light spot passes through the isolated pit region _Ip , the first reproduction signal generation circuit 124 generates the first reproduction signal RS1 and the second reproduction signal generation circuit 116 generates the second reproduction signal RS2. Further, when the position of the light spot of the recording / reproducing laser beam and the position of the light spot of the servo laser beam are shifted in the circumferential direction of the optical axis adjusting optical disk DK0, the first reproduction signal RS1 and the second reproduction signal RS2 are used. There is also a deviation in the occurrence timing of If the generation timings of both reproduction signals RS1 and RS2 can be matched, the positional deviation in the circumferential direction of both laser beams can be corrected.

  In this case, if the interval between the pits formed on the track of the optical disk is narrow, a reproduction signal is continuously generated, and it is difficult to determine which reproduction signal waveform is a waveform when passing through a predetermined pit. Therefore, when a conventional optical disk is used, the reproduction signal cannot be determined.

In contrast, the optical axis adjusting optical disc DK0 of this embodiment is provided with an isolated pit area I _p, both circumferential sides of the isolated pit area I _p is a non-pit area. For this reason, the reproduction signal generated when the light spot passes through the isolated pit region _Ip can be distinguished from other reproduction signals. Further, even if the isolated pit region _Ip is formed by a plurality of pits as shown in FIG. 3, if the both sides in the circumferential direction of the isolated pit region _Ip are non-pit regions, a plurality of pit regions _Ip are formed. The reproduction signal generated when the light spot passes through the isolated pit area _Ip formed by the pits can be distinguished from other reproduction signals, and the reproduction signals corresponding to the respective pits in the isolated pit area _Ip are also included. It can be determined by counting the number of signals.

Therefore, in the digital oscilloscope, the reproduction signal RS1 generated when the light spot of the recording / reproducing laser beam passes through the isolated pit region _Ip and the isolated pit in which the light spot of the servo laser beam is the same as the above isolated pit region. Only the reproduction signal RS2 generated when passing through the region _Ip can be displayed (display step, shift detection step). When the light spot is deviated in the circumferential direction, the generation timing of both reproduction signals is deviated, so that both reproduction signals are displayed deviated. Therefore, by matching the generation timing based on the generation timing of the reproduction signal, it is possible to match the circumferential positions of the light spots.

In particular, as shown in FIG. 4, when the isolated pit area _Ip is formed by one pit on the optical axis adjusting optical disk DK, the light spot is isolated from one non-pit area (area B). When passing through the pit _Ip and entering the other non-pit area (area B), as shown in FIG. 7, one reproduction signal RS1 of the light spot of the recording / reproduction laser beam and the light of the servo laser beam One reproduction signal RS2 of the spot is displayed on the digital oscilloscope. Therefore, it is convenient for comparing both reproduction signals RS1 and RS2.

  When the tracking error signal displayed on the digital oscilloscope is in the state shown in FIG. 7, the operator can select either the laser light emitted from the first laser light source 401 or the laser light emitted from the second laser light source 402. The optical axis of one of the laser beams is adjusted so that the points intersecting with the intermediate line in the left half of the peak shape shown in the drawing of both reproduction signals RS1 and RS2 match (optical axis adjustment step). , Circumferential adjustment step). Here, the intermediate line is a line indicating a value that is a half of the peak value of the reproduction signal, and takes a different value if the peak value of the reproduction signal is different. By this adjustment operation, the circumferential positions of the light spots of the recording / reproducing laser beam and the servo laser beam can be matched. In the above adjustment, if the adjustment is performed by aligning the cursor Cur in the vertical direction at the point where the intermediate line of the reproduction signal and the waveform intersect as shown in FIG. 7, the degree of deviation is known and the adjustment is easy.

  After displaying the first reproduction signal RS1 and the second reproduction signal RS2 on the digital oscilloscope in step S124, the controller 600 determines in step S126 whether or not there has been an input operation indicating that the optical axis adjustment has been completed by the operator. . When the optical axis adjustment for matching the circumferential positions of the two light spots is completed, the operator performs an input operation indicating that the optical axis adjustment has been completed. Then, the controller 600 proceeds to step S128, and the tracking servo control is stopped in step S128. Thereafter, the process returns to step S112.

  In step S <b> 112, the controller 600 displays an adjustment direction input request on the display device 602. When performing the adjustment operation for matching the radial positions of the light spots again, the operator inputs that the optical axis adjustment for the “radial direction” is performed in response to the input request displayed on the display device 602. Then, a tracking error signal is displayed on the digital oscilloscope (S116). Based on the tracking error signal, the operator makes an adjustment again so that the positions of the light spots in the radial direction coincide. On the other hand, when the optical axis adjustment in the circumferential direction is performed again, the operator inputs that the optical axis adjustment in the “circumferential direction” is performed. Then, the reproduction signal is displayed on the digital oscilloscope (S124). Based on this reproduction signal, the operator makes an adjustment again so that the positions of the light spots in the circumferential direction coincide.

  Further, when all the adjustments are finished, an input is made to “end” the adjustment in response to the input request displayed on the display device 602. Then, the determination in step S120 is Yes, and the process proceeds to step S130. In step S130, the controller 600 stops the laser emission from the first laser light source 401 and the second laser light source 402, stops various circuits and devices that have been operated by executing this program, and in step S132, Program execution is terminated.

As described above, according to this example, a track-free region (region A portion) formed over a predetermined radial width on both sides in the radial direction of a predetermined track or a group of tracks (isolated track region I _t ), and at least An optical disc DK0 having a non-pit area (area B) formed over a predetermined circumferential length on both sides in a circumferential direction of a predetermined pit or a group of pits (isolated pit area I _p ) in one track is rotated. However, a plurality of laser beams are irradiated so as to pass through the isolated track region or isolated pit region, and the reflected light from the optical disk DK0 is detected for each of the plurality of laser beams, and a tracking error is based on the reflected light. Signal and playback signal, and based on the generation timing of the tracking error signal and playback signal of each generated light spot, The positional deviation of the plurality of light spots formed on the disk DK0 is detected, and the optical axes of the plurality of laser beams are adjusted based on the detected positional deviation of the plurality of light spots. The tracking error signal generated when the light spot crosses the isolated track area and the reproduction signal generated when the light spot passes through the isolated pit area can be distinguished from other signals. The signal derived from can be clearly grasped. Therefore, based on the comparison result of these signals, the optical axes of the plurality of laser beams can be adjusted so that the radial positions of the light spots coincide.

  Further, the positional deviation of the light spot is such that signals derived from a plurality of light spots are displayed on a digital oscilloscope, and the operator adjusts the optical axis based on the waveform displayed on the digital oscilloscope. For this reason, the operator can visually determine whether or not the optical axis has been adjusted by adjusting the optical axis while viewing the waveform displayed on the digital oscilloscope.

  The present embodiment can be variously modified. For example, in the above embodiment, the tracking error signal is used for adjusting the optical axis in the radial direction, but a reproduction signal (SUM signal) may be used. In this case, when the light spot crosses one track, a waveform with two peaks is generated. Therefore, if the optical axis of the laser beam is adjusted so that the lowest point between the valleys of the two peaks matches. Good.

(Second embodiment)
Next, although 2nd embodiment of this invention is described, this embodiment is the same as said 1st embodiment except the signal evaluation apparatus 300. FIG. The signal evaluation apparatus 300 used in the present embodiment displays a deviation amount between two light spots as a numerical value. In other words, a deviation detection apparatus that detects deviations in positions of a plurality of light spots formed on an optical disc. It is. Therefore, it is not necessary to operate a device such as the digital oscilloscope used in the first embodiment, so that the adjustment work can be performed more efficiently. When the signal evaluation apparatus 300 according to the present embodiment is used, the optical axis adjusting optical disk DK0 has tracks formed only at a predetermined radial position as shown in FIG. It is preferable to use one having only one pit or mark in the pit group or mark group. Further, if the size of the pits or marks in the track of the optical disc DK0 is unified to one size that is an integral multiple of T, which is a unit of the signal length, the optical disc DK0 is rotated at the standard linear velocity. Furthermore, it is more preferable because the slice level can be easily set when the reproduction signal is binarized by a binarization circuit described later.

  FIG. 8 shows a circuit configuration of the signal evaluation apparatus 300 used in this embodiment. As shown in the figure, the signal evaluation apparatus 300 of this example includes four binarization circuits 302, 304, 306, 308, an inter-track crossing time detection circuit 320, two switching circuits 310, 312, and a pulse width. It has a measuring device 318.

  Of the four binarization circuits, the first binarization circuit 302 receives the reproduction signal generated by the first reproduction signal generation circuit 124, and the second binarization circuit 304 inputs to the second reproduction signal generation circuit 116. The third binarization circuit 306 receives the tracking error signal generated by the first tracking error signal generation circuit 122, and the fourth binarization circuit 308 generates the second tracking error signal. The tracking error signal generated by the circuit 110 is input.

  The first binarization circuit 302 and the second binarization circuit 304 are circuits that convert a reproduction signal into a high level and a low level pulse signal based on a predetermined slice level (threshold). The third binarization circuit 306 and the fourth binarization circuit 308 are circuits that convert a tracking error signal into a high level and a low level pulse signal by detecting a predetermined slice level (threshold) or a predetermined signal. When the portion corresponding to the pit or mark formed on the track of the optical disc DK0 is unified to one length that is an integral multiple of T, which is the unit of the signal length, the optical disc DK0 is set to the standard linear velocity. To generate a reproduction signal, and input a pulse signal output from the binarization circuits 302 and 304 to a pulse width measuring device 318 to be described later. When the pulse width is measured, the pulse width is a predetermined value or a desired value. The slice levels of the binarization circuits 302 and 304 are set so as to be values.

  FIG. 9 is a diagram showing a circuit configuration of the third binarization circuit 306 and the fourth binarization circuit 308. As shown in the figure, the third binarization circuit 306 and the fourth binarization circuit 308 are composed of a zero cross point detection circuit 10, a track crossing end detection circuit 12, a mask signal generation circuit 16, and a binary signal generation. Circuit 14.

  As shown in FIG. 11 showing the waveform of the tracking error signal, the zero-cross point detection circuit 10 has a tracking error signal TE input from the first and second tracking error signal generation circuits 110 and 122 having a predetermined positive peak value A. After that, a point (zero cross point) that crosses the zero point is detected, and a zero cross detection signal is output to the binarized signal generation circuit 14. The zero cross detection signal is output when the light spot reaches the central portion in the radial direction of the track. The track crossing end detection circuit 12 detects a point where the tracking error signal TE crosses the level value B2 set to a value slightly lower than the zero point after the tracking error signal TE becomes smaller than a predetermined negative peak value B1, and crosses the track. The detection signal is output to the binary signal generation circuit 14. The track crossing detection signal is output when the light spot almost completes the track crossing.

  The mask signal generation circuit 16 outputs a signal (mask signal) having a predetermined pulse width when the tracking error signal TE crosses the zero point after the tracking error signal TE becomes smaller than the predetermined negative peak value C. And output to the track crossing end detection circuit 12. While the mask signal is output from the mask signal generation circuit 16 to the zero cross point detection circuit 10 and the track crossing end detection circuit 12, the zero cross point detection circuit 10 and the track crossing end detection circuit 12 detect the detection signals (zero cross point detection signal, The track crossing detection signal) is not output to the binarized signal generation circuit 14. The mask signal generation circuit 16 has two types of cases, that is, a case where the light spot irradiated to the optical axis adjusting optical disk DK0 crosses the track from the outside in the radial direction to the inside and the case where the light spot crosses from the inside in the radial direction to the outside. In other words, since the shape of the signal generated in each is different, only a tracking error signal that first changes to a positive level is a circuit for binarization processing. That is, in the case of the tracking error signal having the waveform shown in FIG. 11, the mask signal is output after the zero-cross point detection signal and the track crossing detection signal are output, so that the zero cross point and the track crossing may be detected. However, when the tracking error signal having the waveform shown in FIG. 12 is output (that is, when the light spot crosses the track from the direction opposite to the direction in which the tracking error signal shown in FIG. 11 is generated), Since the mask signal is output first, the zero cross point detection signal and the track crossing detection signal are not output. The binarized signal generation circuits 302, 304, 306, and 308 are flip-flop circuits. The first binarization circuit 302 and the second binarization circuit 304 are pulse signals that become a low level when the value of the reproduction signal is equal to or lower than a predetermined slice level and become a high level when the value exceeds a predetermined slice level. Is output. The third binarization circuit 306 and the fourth binarization circuit 308 are at a high level when a signal is input from the zero cross point detection circuit, and are at a low level when a signal is input from the track crossing end detection circuit. Outputs a pulse signal.

  The first signal switching circuit 310 operates in accordance with an instruction from the controller 600, and a binarized reproduction signal (first reproduction pulse signal) input from the first binarization circuit 302 and a third binarization circuit 306. The binarized tracking error signal (first tracking error pulse signal) inputted from is selectively output to the first evaluation signal generation circuit 314 and the second evaluation signal generation circuit 316. The second signal switching circuit 312 operates in response to an instruction from the controller 600, and a binarized reproduction signal (second reproduction pulse signal) input from the second binarization circuit 304 and a fourth binarization circuit 308. Are selectively output to the first evaluation signal generation circuit 314 and the second evaluation signal generation circuit 316.

  The first evaluation signal generation circuit 314 is a flip-flop circuit, which changes to a high level when the input first reproduction pulse signal or the first tracking error pulse signal becomes a high level, and receives the second reproduction input. When the pulse signal or the second tracking error pulse signal becomes a high level, a pulse signal (first evaluation pulse signal) that changes to a low level is generated, and the generated first evaluation pulse signal is used as a pulse width measuring device 318. Output to. The second evaluation signal generation circuit 316 is also a flip-flop circuit, and changes to a low level when the input first reproduction pulse signal or the first tracking error pulse signal becomes a high level, and is input to the second reproduction signal. A pulse signal (second evaluation pulse signal) that changes to a high level when the pulse signal or the second tracking error pulse signal becomes a high level is generated, and the generated second evaluation pulse signal is used as a pulse width measuring device 318. Output to.

  The pulse width measuring device 318 measures the pulse width of the input first evaluation pulse signal and the second evaluation pulse signal, such as a time interval analyzer, for example, and expresses a mean value and a numerical value representing variations such as a standard deviation. Is output. The pulse width measuring device 318 measures the pulse width of one of the two evaluation signals input in accordance with an instruction from the controller 600 and outputs the measurement result (average value of the pulse width) to the controller 600. To do.

FIG. 10 is a diagram showing a circuit configuration of the inter-track crossing time detection circuit 320. As shown in the figure, the cross-track time detection circuit 320 includes a zero cross point detection circuit 20, a mask signal generation circuit 26, a time measurement circuit 22, and an average value calculation circuit 24. The zero cross point detection circuit 20 has the same function as the zero cross point detection circuit 10 described above. The mask signal generation circuit 26 also has the same function as the mask signal generation circuit 16 described above. The time measuring circuit 22 is a circuit having a built-in reference clock, and starts to operate according to an instruction from the controller 600. The time measurement circuit 22 starts time measurement when the zero cross point detection signal from the zero cross point detection circuit 20 is input, and ends time measurement when the next zero cross point detection signal is input, and the measured time is an average value. Output to calculation circuit. Thereby, the time from when the light spot crosses one track or track group (isolated track region) to when it crosses the next adjacent track or track group (isolated track region) is measured. In the present embodiment, since the radial direction on both sides of the isolated track area I _t has no track area is formed, the time measuring circuit 22, the light spot free track area is detected the time to traverse become.

  Time measurement by the time measurement circuit 22 is repeated, and when a stop signal is input from the average value calculation circuit 24, the time measurement is stopped. The average value calculation circuit 24 starts to operate according to an instruction from the controller 600. The average value calculation circuit 24 has a built-in memory, and stores the time data input from the time measurement circuit 22 in the memory after the operation is started. When the stored time data reaches a predetermined number, storage by the memory is stopped, a stop signal is output to the time measurement circuit 22, an average value of the stored time data is calculated, and a calculation result is output to the controller 600. Then, all stored data is reset and the operation is stopped.

  The signal evaluation apparatus 300 used in this embodiment has the above configuration. Since the configuration of the laser light irradiation apparatus is the same as the laser light irradiation apparatus described in the first embodiment, the laser light irradiation apparatus 1 of FIG. 1 is also used in this embodiment, and the specific description thereof is omitted. .

  In the present embodiment, the operator connects the signal evaluation apparatus 300 having the above configuration to the laser light irradiation apparatus 1. The connection configuration is the same as in the first embodiment. And the laser beam irradiation apparatus 1 is started, the input device 604 is operated, and the signal evaluation program shown in FIGS. 13-15 is performed.

  The signal evaluation program of this embodiment is started in step S200 of FIG. 13, and the controller 600 outputs a command to start the operation to the feed motor control circuit 504 in step S202. As a result, the feed motor control circuit 504 controls the drive of the feed motor 503 so that the laser light from the first laser light source 401 and the second laser light source 402 is irradiated to a predetermined radial direction position of the optical axis adjusting optical disk DK0. Thus, the position of the turntable 505 is adjusted. Next, in step S <b> 204, the controller 600 outputs a command to start operation to the spindle motor control circuit 502. As a result, the spindle motor control circuit 502 controls the driving of the spindle motor 501, and the optical axis adjusting optical disk DK0 is rotated on the turntable 505 at a predetermined linear velocity. This linear velocity is a predetermined standard value. The linear velocity is stored in the controller 600 (linear velocity specifying step).

  Next, in step S206, the controller 600 outputs a command to start driving to the servo laser driving circuit 200. As a result, servo laser light is emitted from the second laser light source 402 (laser light irradiation step). Subsequently, in step S208, a command to start driving is output to the recording / reproducing laser driving circuit 202. Thereby, the recording / reproducing laser beam is emitted from the first laser light source 401 (laser beam irradiation step). By the processes in steps S206 and S208, the servo laser light and the recording / reproducing laser light enter the optical axis adjusting optical disk DK0 along a predetermined path, and a light spot is formed on the optical axis adjusting optical disk DK0. The reflected light from the optical axis adjusting optical disk DK0 is received by the first photodetector 410 and the second photodetector 413, and the focus error signal is generated by the focus error signal generation circuit 104 based on the received light signal. The first tracking error signal (crossing signal) is generated by the signal generation circuit 122, the second tracking error signal (crossing signal) is generated by the second tracking error signal generation circuit 110, and the first reproduction signal generation circuit 124 performs the first reproduction. A second reproduction signal (pass signal) is generated by the second reproduction signal generation circuit 116 as a signal (pass signal) (signal generation step).

  The first reproduction signal generated by the first reproduction signal generation circuit 124 is input to the first binarization circuit 302 of the signal evaluation apparatus 300, and the first binarization circuit 302 outputs 2 at a predetermined slice level. It is converted into a quantified pulse signal (passage signal binarization step) and output to the first signal switching circuit 310 as a first reproduction pulse signal. The second reproduction signal generated by the second reproduction signal generation circuit 116 is input to the second binarization circuit 304 of the signal evaluation apparatus 300, and the second binarization circuit 304 uses a predetermined slice level. It is converted into a binarized pulse signal (passing signal binarization step), and is output to the second signal switching circuit 312 as a second reproduction pulse signal.

  The first tracking error signal generated by the first tracking error signal generation circuit 122 is input to the third binarization circuit 306 of the signal evaluation apparatus 300, and is binarized by the third binarization circuit 306. Converted to a pulse signal (transverse signal binarization step) and output to the first signal switching circuit 310 as a first tracking error pulse signal. The second tracking error signal generated by the second tracking error signal generation circuit 110 is input to the fourth binarization circuit 308 of the signal evaluation apparatus 300, and binarized by the fourth binarization circuit 308. Converted to a pulse signal (transverse signal binarization step) and output to the second signal switching circuit 312 as a second tracking error pulse signal.

  Next, the controller 600 starts focus servo control in step S210 and performs focus pull-in. In step S210, the focus servo circuit 106 outputs a control signal for the focus actuator 415 to the focus actuator drive circuit 108 based on the focus error signal input from the focus error signal generation circuit 104, whereby the light spot of the optical disc DK0 is output. The position of the objective lens 403 is controlled so as to focus on the recording surface. Next, in step S212, the controller 600 displays an adjustment direction input request on the display device 602. In response to the input request displayed on the display device 602, the operator adjusts the position of the light spot in the radial direction of the optical axis adjusting optical disk DK0, in the circumferential direction, or finishes the adjustment. select. Subsequently, in step S214, the controller 600 determines whether or not the adjustment direction input from the operator in response to the input request in step S212 is the “radial direction”. If it is in the radial direction, the process proceeds to step S216 (FIG. 14). If it is not “radial direction”, the process proceeds to step S244.

  If the determination result in step S214 is “Yes” and the process proceeds to step S216, the controller 600 outputs a tracking error signal from the first signal switching circuit 310 and the second signal switching circuit 312 in this step S216. As described above, switching control of the signal switching circuits 310 and 312 is performed. Accordingly, the first tracking error pulse signal is input to the first evaluation signal generation circuit 314 and the second evaluation signal generation circuit 316 via the first signal switching circuit 310, and the second tracking error pulse signal is changed to the first tracking error pulse signal. The signal is input to the first evaluation signal generation circuit 314 and the second evaluation signal generation circuit 316 via the two-signal switching circuit 312. As described above, the first evaluation signal generation circuit 314 becomes high level when the input first tracking error pulse signal becomes high level, and the input second tracking error pulse signal becomes high level. A first evaluation pulse signal (crossing signal evaluation pulse signal) that becomes a low level is generated (crossing signal comparison step). The generated first evaluation pulse signal is input to the pulse width measuring device 318. As described above, the second evaluation signal generation circuit 316 becomes low level when the input first tracking error pulse signal becomes high level, and the input second tracking error signal becomes high level. A second evaluation pulse signal (transverse signal evaluation pulse signal) that sometimes becomes high level is generated (transverse signal comparison step). The generated second pulse signal for evaluation is input to the pulse width measuring device 318.

  Next, in step S218, the controller 600 starts the operation of the time measuring circuit 22 in the inter-track crossing time detection circuit 320. Thereby, the operation of the inter-track crossing time detection circuit 320 is started, and the time detected by the cross-track crossing time detection circuit 320 (the time when the light spot of the recording / reproducing laser beam crosses the non-track area) is given to the controller 600. Input (track crossing time detection step). The controller 600 stores the input crossing time between tracks.

Next, in step S220, the pulse width of the first evaluation pulse signal input to the pulse width measuring device 318 is measured. Here, FIG. 16 shows the positional relationship between the light spot of the recording / reproducing laser beam and the light spot of the servo laser beam when both the signal switching circuits 310 and 312 output the tracking error pulse signal (case 1, According to case 2), a first tracking error signal generation circuit 122, a second tracking error signal generation circuit 110, a third binarization circuit 306, a fourth binarization circuit 308, a first evaluation signal generation circuit 314, and It is the figure which showed the signal waveform produced | generated in the signal generation circuit 316 for 2nd evaluation. As shown in (A) FIG Case 1 of Figure 16, the light spot of the reproducing laser beam across the previously isolated track area I _t, an isolated track area I _t after the light spot of the servo laser beam In the case of crossing, the first tracking error signal TE1 generated by the first tracking error signal generation circuit 122 (FIG. 16 (a) in FIG. 16) is generated by the second tracking error signal generation circuit 110. Is preceded by the second tracking error signal TE2 (FIG. 16B, FIG. 16B). Therefore, the first tracking error pulse signal PS _TE 1 (FIG. 16C of FIG. 16) generated by the third binarization circuit 306 is also generated by the fourth binarization circuit 308. It precedes the double tracking error pulse signal PS _TE 2 (FIG. 16 (d)). Therefore, in the first evaluation pulse signal PS _EV 1 (FIG. 16 (e) in FIG. 16) generated by the first evaluation signal generation circuit 314, the first tracking error pulse signal PS _TE 1 is at a high level. Only a short section from when the second tracking error pulse signal PS _TE 2 becomes high level becomes a high level, and the other section becomes a low level (that is, the high level section is short). The first evaluation pulse signal PS _EV 1 is output to the pulse width measuring device 318. In case 1 of FIG. 16 (when the light spot of the recording / reproducing laser beam precedes the light spot of the servo laser beam), the width of the high level section of the first evaluation pulse signal PS _EV 1 (hereinafter referred to as “high”). ) of pulse width the width of the level section, the timing at which each of the light spot traverses the isolated track area I _t, that is a unit of a shift amount time generation timing of the tracking error signal from each of the light spot This timing deviation amount indirectly represents the radial position deviation amount of both light spots.

On the other hand, in the second evaluation pulse signal PS _EV 2 (FIG. 16 (f) in FIG. 16) generated by the second evaluation signal generation circuit 316, the second tracking error pulse signal PS _TE 2 is at a high level. until a low level, the second tracking error pulse signal PS TE ₂ becomes high level when the high level. When the first tracking error pulse signal PS _TE 1 becomes high level, it becomes low level. In the case 1, the optical spot of the recording / reproducing laser beam corresponding to the first tracking error pulse signal PS _TE 1 precedes the optical spot of the servo laser beam corresponding to the second tracking error pulse signal PS _TE 2. are therefore one of the isolated track region I _t in the course of both the light spot traverses, a first tracking error pulse signal PS TE ₁ becomes high level after the second tracking error pulse signal PS TE ₂ has become the high level There is nothing. Accordingly, the second evaluation pulse signal PS EV _2, once when the high level, both the light spot passes through the non-track area, the next isolated track area I _t light spot of the recording reproducing laser beam cross Until then, the high level is maintained, and changes to the low level when the light spot of the recording / reproducing laser beam crosses the next isolated track area. Therefore, the pulse width of PS _EV 2 is very long compared to the pulse width of PS _EV 1. The second evaluation signal generation circuit 316 outputs such a second evaluation pulse signal PS _EV 2 to the pulse width measuring device 318.

Further, as shown in (A) FIG Case 2 of Figure 16, the light spot of the servo laser beam to traverse the previously isolated track area I _t, after the light spot of the reproducing laser beam is isolated track area I _When crossing _t , the second tracking error signal TE2 generated by the second tracking error signal generation circuit 110 (FIG. 16B in FIG. 16) is generated by the first tracking error signal generation circuit 122. Is preceded by the first tracking error signal TE1 (FIG. 16A in FIG. 16). Therefore, the second tracking error pulse signal PS _TE 2 (FIG. _{16D in} FIG. 16) generated by the fourth binarization circuit 308 is also generated by the third binarization circuit 306. It precedes one tracking error pulse signal PS _TE 1 (FIG. 16 (c)). Therefore, in the second evaluation pulse signal PS _EV 2 (FIG. 16 (f) in FIG. 16) generated by the second evaluation signal generation circuit 316, the second tracking error pulse signal PS _TE 2 is at a high level. Only a short section from when the first tracking error pulse signal PS _TE 1 becomes high level becomes a high level, and the other section becomes a low level (that is, the high level section is short), and this pulse signal Such a second evaluation pulse signal PS _EV 2 is output to the pulse width measuring device 318. In the case 2 of FIG. 16 (when the light spot of the servo laser light precedes the light spot of the recording / reproducing laser light), the pulse width of the second evaluation pulse signal PS _EV 2 is determined by the respective light spots. There represents the isolation timing when crossing the track area I _t, that is, the shift amount of the generation timing of the tracking error signal from each of the light spot in units of time, the deviation amount of the timing, the radial direction of both the light spot The amount of misalignment is indirectly shown.

On the other hand, in the first evaluation pulse signal PS _EV 1 (FIG. 16 (e) in FIG. 16) generated by the first evaluation signal generation circuit 314, the first tracking error pulse signal PS _TE 1 is at a high level. Until the first tracking error pulse signal PS _TE 1 becomes high level. When the second tracking error pulse signal _PSTE2 becomes high level, it becomes low level. In the case 2, the optical spot of the servo laser beam corresponding to the second tracking error pulse signal PS _TE 2 precedes the optical spot of the recording / reproducing laser beam corresponding to the first tracking error pulse signal PS _TE 1. because there, one of the isolated track region I _t in the course of both the light spot traverses, a second tracking error pulse signal PS TE ₂ becomes high level after the first tracking error pulse signal PS TE ₁ has become the high level There is nothing. Thus, the first evaluation pulse signal PS EV _1, once when the high level, both the light spot passes through the non-track area, the next isolated track area I _t is a light spot of the servo laser beam to traverse until maintained much high, the next isolated track area I _t is a light spot of the servo laser beam is changed to a low level when crossing. Therefore, the pulse width of PS _EV 1 is much longer than the pulse width of PS _EV 2. The first evaluation signal generation circuit 314 outputs the first evaluation pulse signal PS _EV 1 to the pulse width measuring device 318.

In step S <b> 220, the pulse width measurement device 318 measures the pulse width of the first evaluation pulse signal PS _EV 1 input from the first evaluation signal generation circuit 314 and outputs the pulse width to the controller 600. In step S222, it is determined whether the input pulse width is equal to or less than a predetermined pulse width Δ1. Here, as described above, the amount of deviation of timing at which the first evaluation pulse signal PS EV ₁ and the light spot of the light spot and the servo laser beam of the recording reproducing laser beam traverses the isolated track area I _t 16 represents a relatively short pulse width corresponding to the amount of deviation as shown in FIG. 16 (e) in case 1 of FIG. 16, otherwise, the pulse width of case 1 in FIG. f) It becomes long as shown in the figure. Therefore, the predetermined pulse width Δ1 is set to such a length (time) that it can be discriminated whether the pulse width of the first evaluation pulse signal PS _EV 1 to be compared represents the deviation amount.

When it is determined in step S222 that the pulse width of the first evaluation pulse signal PS _EV 1 is Δ1 or less, the light spot of the recording / reproducing laser beam precedes the light spot of the servo laser beam. In addition, it can be seen that the positional deviation in the radial direction of both light spots is represented by the pulse width of the first evaluation pulse signal PS _EV 1. In this case, the process proceeds to step S224. Otherwise, the process proceeds to step S232.

When the process proceeds from step S222 to step S224, the actual radial displacement amount between the light spot of the recording laser beam and the light spot of the servo laser beam is calculated in step S224 (deviation amount calculation step). As described above, the pulse width of the first evaluation pulse signal PS EV ₁ is for each of the light spot represents the deviation of the timing when crossing the isolated track area I _t, since the unit is time In order to calculate the actual positional deviation amount, it is necessary to convert the timing deviation amount obtained from the pulse width into a unit of length. Here, the time detected by the cross-track crossing time detection circuit 320 is output to the controller 600, and this detection time is the time for the light spot to cross the non-track region. Further, since the radial width of the track-free area can be known from the optical axis adjusting optical disk DK0, the light spot is changed in the radial direction of the optical disk DK0 by dividing the radial width (known) of the track-free area by the detection time. The moving speed can be calculated. By multiplying this speed by the pulse width of the first evaluation pulse signal PS _EV 1, the moving distance corresponding to the timing difference between the two light spots is calculated. This moving distance represents the amount of positional deviation in the radial direction of both light spots. In step S224, the positional deviation amount of both light spots is calculated in this way (deviation amount calculating step).

After calculating the positional deviation amount in the radial direction of both light spots in step S224, the controller 600 records and reproduces the calculated radial positional deviation amount and the optical spot of the servo laser beam in step S226. The shift direction of the laser beam for the optical spot is displayed on the display device 602. Here, the shift direction indicates, for example, whether the light spot of the servo laser beam is shifted outward or inward in the radial direction with respect to the light spot of the recording laser beam. Incidentally, the deviation direction is the first photodetector 410, the light receiving signal in the second photodetector 413 (A, B, C, D) so varies depending on how define the areas and positions corresponding to, in advance PS EV ₁ is When the positional deviation between the two light spots is represented, it is necessary to determine whether the deviation direction is inward or outward in the radial direction.

On the other hand, if it is determined in step S222 that the pulse width is larger than Δ1, the two light spots are not in the positional deviation relationship as shown in FIG. 2 is predicted to have a positional shift relationship as shown in FIG. Accordingly, in this case, the process proceeds to step S232, and the pulse width of the second evaluation pulse signal PS _EV 2 generated by the second evaluation signal generation circuit 316 is measured in step S232. Then, in the next step S234, it is determined whether the measured pulse width is equal to or smaller than a predetermined width Δ2. This width Δ2 is set in the same manner as Δ1.

When it is determined in step S234 that the pulse width of the second evaluation pulse signal PS _EV 2 is Δ2 or less, the light spot of the servo laser light precedes the light spot of the recording / reproducing laser light, and both It can be seen that the radial displacement of the light spot is represented by the pulse width of the second evaluation pulse signal PS _EV 2. In this case, the process proceeds to step S236. Otherwise, the process proceeds to step S240.

Proceeding to step S240 means that the determination in step S222 is “No” and the determination in step S234 is also “No”. This means that both the pulse width of the first evaluation pulse signal PS _EV 1 and the pulse width of the second evaluation pulse signal PS _EV 2 are larger than the predetermined pulse width, and the light spot is isolated from the optical disc DK0. it is contemplated that the tracking error signal generated is not properly inputted when crossing a track I _t. Therefore, in this case, it is considered that some abnormality has occurred in the apparatus, so the abnormality is displayed on the display device 602 in step S240, and the execution of this program is terminated in step S242.

  If it is determined in step S234 that the pulse width is equal to or less than Δ2 and the process proceeds to step S236, the actual radial displacement between the light spot of the servo laser light and the light spot of the recording / reproducing laser light in step S236. The amount is measured (shift amount calculation step). The measurement of the radial position deviation amount is performed by a method similar to the method shown in step S224 described above.

After calculating the radial position deviation amount of both the light spots in step S236, the controller 600 records and reproduces the calculated radial position deviation amount and the optical spot of the servo laser beam in step S238. The shift direction of the laser beam with respect to the light spot is displayed on the display device 602. Here, the shift direction indicates, for example, whether the light spot of the servo laser beam is shifted outward or inward in the radial direction with respect to the light spot of the recording / reproducing laser beam. In the case where PS _EV 2 represents the positional deviation between the two light spots, it is necessary to determine whether the deviation direction is inward or outward in the radial direction as in the case of PS _EV 1.

  After displaying the radial position displacement amount and the displacement direction of the light spot on the display device 602 in step S226 or step S238, the controller 600 determines in step S228 whether a predetermined time has elapsed. During this time, the operator operates the first laser light source 401 or the second laser light source 402 of the laser light irradiation device 1 and sets the optical axis of the laser light so that the displayed radial displacement is zero. Adjust (optical axis adjustment step, radial direction adjustment step). After a predetermined time has elapsed, the controller 600 proceeds to step S230, and determines whether an input indicating the end of the radial adjustment has been input by the operator. When ending the optical axis adjustment in the radial direction, the operator performs an input operation indicating “end” via the input device 604. On the other hand, when the optical axis adjustment in the radial direction is performed again, nothing is done as it is. When the controller 600 determines that an input operation indicating “end” has been performed by the worker (step S230: Yes), the controller 600 returns to step S212. When it is determined that the input operation indicating “end” has not been performed (step S230: No), the process returns to step S220, and the operations of steps S222 to S228 and / or steps S232 to S238 are repeated.

  If it is determined in step S230 that an input operation indicating “end” has been performed (step S230: Yes) and the process returns to step S212, an input request for an adjustment direction is displayed on the display device 602 in step S212. In response to the input request displayed on the display device 602, the operator adjusts the position of the light spot in the “radial direction”, the “circumferential direction” or the adjustment of the optical axis adjustment optical disk DK0. Select whether to end. Subsequently, in step S214, the controller 600 determines whether or not the adjustment direction input from the operator in response to the input request in step S212 is the “radial direction”. If it is “radial direction”, the process proceeds to step S216. If it is not “radial direction”, the process proceeds to step S244.

  When the process proceeds from step S214 to step S216, the positional deviation amount in the radial direction of both light spots is calculated based on the tracking error signal as described above. On the other hand, when the process proceeds from step S214 to step S244, it is determined whether or not the operator inputs “end” the adjustment in response to the input request in step S212. If there is an input request to “end” the adjustment (S244: Yes), the process proceeds to step S276. If not, that is, if the adjustment direction is “circumferential direction”, the process proceeds to step S246.

  If the adjustment direction input by the operator in response to the input request in step S212 is “circumferential direction”, the process proceeds to step S246 via step S244, and tracking servo is started in step S246. Accordingly, the tracking servo circuit 112 controls the tracking actuator 414 via the tracking actuator drive circuit 114 based on the second tracking error signal generated by the second tracking error signal generation circuit 110. For this reason, the objective lens 403 slightly moves so that the light spot of the servo laser light follows the track T formed on the optical axis adjusting optical disk DK0. At this time, if the radial position of the optical spot of the recording / reproducing laser beam coincides with the radial position of the optical spot of the servo laser beam, the optical spot of the recording / reproducing laser beam is also the light of the servo laser beam. Track T along with the spot. In this embodiment, since the optical axis adjusting optical disk DK0 has a track formed only at a predetermined radial position, an S-shaped signal in the tracking error signal (when traversing the track) The method of starting tracking servo control when the wavelength of the signal) becomes the longest cannot be used. In this case, the tracking servo is pulled in by reducing the number of revolutions of the optical disk, starting tracking servo control from the time when the tracking error signal crosses zero, and gradually increasing the number of revolutions of the optical disk to return to the original number of revolutions. .

  Next, in step S248, the controller 600 performs switching control of the signal switching circuits 310 and 312 so that the reproduction signal is output from the first signal switching circuit 310 and the second signal switching circuit 312. As a result, the first reproduction pulse signal generated by binarizing the first reproduction signal at a predetermined slice level by the first binarization circuit 302 is sent to the first evaluation signal via the first signal switching circuit 310. The second reproduction pulse signal generated by being input to the generation circuit 314 and the second evaluation signal generation circuit 316 and binarized by the second binarization circuit 304 at a predetermined slice level. Is input to the first evaluation signal generation circuit 314 and the second evaluation signal generation circuit 316 via the second signal switching circuit 312. The first evaluation signal generation circuit 314 becomes high level when the inputted first reproduction pulse signal becomes high level, and becomes low level when the inputted second reproduction pulse signal becomes high level. A first evaluation pulse signal is generated (passing signal comparison step). The generated first evaluation pulse signal is input to the pulse width measuring device 318. The second evaluation signal generation circuit 316 becomes low level when the inputted first reproduction pulse signal becomes high level, and becomes high level when the inputted second reproduction pulse signal becomes high level. A second evaluation pulse signal is generated (passing signal comparison step). The generated second pulse signal for evaluation is input to the pulse width measuring device 318.

In step S250, the pulse width measuring device 318 measures the pulse width of the input first evaluation pulse signal, and the measurement result is input to the controller 600. Here, FIG. 17 shows the positional relationship between the light spot of the recording / reproducing laser beam and the light spot of the servo laser beam when both the signal switching circuits 310 and 312 output the reproduction pulse signal (case 1, case 2), the first reproduction signal generation circuit 124, the second reproduction signal generation circuit 116, the first binarization circuit 302, the second binarization circuit 304, the first evaluation signal generation circuit 314, and the second evaluation It is the figure which showed the signal waveform produced | generated in the signal generation circuit 316. As shown in FIG. 17A (A), the light spot of the recording / reproducing laser beam first passes through the isolated pit region _Ip, and the light spot of the servo laser beam later passes through the isolated pit region _Ip . When passing, the first reproduction signal RS1 generated by the first reproduction signal generation circuit 124 (FIG. 17A in FIG. 17) is generated by the second reproduction signal generation circuit 116. It precedes the second reproduction signal RS2 (FIG. 17 (b)). Therefore, the first reproduction pulse signal PS _RS 1 generated by the first binarization circuit 302 (FIG. 17 (c) in FIG. 17) is also generated by the second binarization circuit 304. It precedes the reproduction pulse signal PS _RS 2 (FIG. 17 (d)). Therefore, in the first evaluation pulse signal PS _EV 1 (FIG. 17 (e)) generated by the first evaluation signal generation circuit 314, the first reproduction pulse signal PS _RS 1 is at a high level. Only a short section from when the second reproduction pulse signal PS _RS 2 becomes high level becomes a high level, and the other period becomes a pulse signal that becomes low level (that is, the high level period is short). The first evaluation pulse signal PS _EV 1 is output to the pulse width measuring device 318. In the case 1 of FIG. 17 (when the light spot of the recording / reproducing laser beam precedes the light spot of the servo laser beam), the pulse width of the first evaluation pulse signal PS _EV 1 is determined by the respective light spots. timing when passing through the isolated pit area I _P, i.e. represents the shift amount of the generation timing of the reproduction signal from each of the light spot in units of time, the deviation amount of the timing, the position in the circumferential direction of both the light spot The amount of deviation is shown indirectly.

On the other hand, in the second evaluation pulse signal PS _EV 2 (FIG. 17 (f) in FIG. 17) generated by the second evaluation signal generation circuit 316, the second reproduction pulse signal PS _RS 2 is at a high level. Until then, it is at a low level, and when the second reproduction pulse signal PS _RS 2 becomes a high level, it becomes a high level. When the first reproduction pulse signal PS _RS 1 becomes high level, it becomes low level. In the case 1, the light spot of the recording / reproducing laser beam corresponding to the first reproduction pulse signal PS _RS 1 precedes the light spot of the servo laser beam corresponding to the second reproduction pulse signal PS _RS 2. In the process in which both light spots pass through one isolated pit region _Ip , the first reproduction pulse signal PS _RS 1 does not become high level after the second reproduction pulse signal PS _RS 2 becomes high level. Therefore, when the second evaluation pulse signal PS _EV 2 once becomes high level, both light spots pass through the non-pit area, and the light spot of the recording / reproducing laser beam passes through the next isolated pit area _Ip. The high level is maintained until it passes, and the level changes to the low level when the light spot of the recording / reproducing laser beam passes through the next isolated pit region _Ip . Therefore, the pulse width of PS _EV 2 is very long compared to the pulse width of PS _EV 1. The second evaluation signal generation circuit 316 outputs such a second evaluation pulse signal PS _EV 2 to the pulse width measuring device 318.

Further, as shown in FIG. 17A in case 2 of FIG. 17, the light spot of the servo laser beam first passes through the isolated pit region _Ip, and the light spot of the recording / reproducing laser beam later passes through the isolated pit region I. _When passing _p , the second reproduction signal RS2 generated by the second reproduction signal generation circuit 116 (FIG. 17B) is generated by the first reproduction signal generation circuit 124. It precedes one reproduction signal RS1 (FIG. 17A, FIG. 17A). Accordingly, the second reproduction pulse signal PS _RS 2 (FIG. 17D of FIG. 17) generated by the second binarization circuit 304 is also generated by the first binarization circuit 302. It precedes the reproduction pulse signal PS _RS 1 ((c) diagram of case 2 in FIG. 17). Therefore, in the second evaluation pulse signal PS _EV 2 (FIG. 17 (f) in FIG. 17) generated by the second evaluation signal generation circuit 316, the second reproduction pulse signal PS _RS 2 is at a high level. Only a short interval from when the first reproduction pulse signal PS _RS 1 becomes high level becomes a high level, and the other intervals become low level (that is, the high level interval is short). The second evaluation pulse signal PS _EV 2 is output to the pulse width measuring device 318. In the case 2 of FIG. 17 (when the light spot of the servo laser light precedes the light spot of the recording / reproducing laser light), the pulse width of the second evaluation pulse signal PS _EV 2 is determined by the respective light spots. Represents the timing when the signal passes through the isolated pit region _Ip , that is, the amount of deviation of the generation timing of the reproduction signal derived from each light spot, in units of time. Indirectly indicates the amount of displacement.

On the other hand, in the first evaluation pulse signal PS _EV 1 (FIG. 17 (e) in FIG. 17) generated by the first evaluation signal generation circuit 314, the first reproduction pulse signal PS _RS 1 is at a high level. Until this time, it is at a low level, and becomes a high level when the first reproduction pulse signal PS _RS 1 becomes a high level. When the second reproduction pulse signal PS _RS 2 becomes high level, it becomes low level. In the case 2, the optical spot of the servo laser beam corresponding to the second reproduction pulse signal PS _RS 2 precedes the optical spot of the recording / reproduction laser beam corresponding to the first reproduction pulse signal PS _RS 1. In the process in which both light spots pass through one isolated pit region _Ip , the second reproduction pulse signal PS _RS 2 does not become high level after the first reproduction pulse signal PS _RS 1 becomes high level. Accordingly, when the first evaluation pulse signal PS _EV 1 once becomes a high level, the light spot passes through the non-pit area, and the light spot of the servo laser light crosses the next isolated pit area _Ip. The high level is maintained for a long time, and when the servo laser beam passes through the next isolated pit region _Ip , the level changes to the low level. Therefore, the pulse width of PS _EV 1 is very long compared to the pulse width of PS _EV 2. The first evaluation signal generation circuit 314 outputs the first evaluation pulse signal PS _EV 1 to the pulse width measuring device 318.

In step S <b> 250, the pulse width measuring device 318 measures the pulse width of the first evaluation pulse signal PS _EV 1 input from the first evaluation signal generation circuit 314 and outputs the pulse width to the controller 600. In step S252, it is determined whether the input pulse width is equal to or less than a predetermined pulse width Δ3. Here, as described above, the amount of timing deviation when the first evaluation pulse signal PS _EV 1 passes through the isolated pit region _Ip between the light spot of the recording / reproducing laser beam and the light spot of the servo laser beam. 17 represents a relatively short pulse width corresponding to the amount of deviation as shown in FIG. 17E in case 1 of FIG. 17, otherwise, the pulse width of case 1 in FIG. f) It becomes long as shown in the figure. Therefore, the predetermined pulse width Δ3 is set to such a length (time) that it can be identified whether the pulse width of the first evaluation pulse signal PS _EV 1 to be compared represents the deviation amount.

When it is determined in step S252 that the pulse width of the first evaluation pulse signal PS _EV 1 is Δ3 or less, the light spot of the recording / reproducing laser beam precedes the light spot of the servo laser beam. In addition, it can be seen that the positional deviation in the circumferential direction of both light spots is represented by the pulse width of the first evaluation pulse signal PS _EV 1. In this case, the process proceeds to step S254. Otherwise, the process proceeds to step S262.

When the process proceeds from step S252 to step S254, an actual circumferential displacement amount between the light spot of the recording / reproducing laser beam and the light spot of the servo laser beam is calculated in step S254 (deviation amount calculating step). . Here, as described above, the pulse width of the first evaluation pulse signal PS _EV 1 represents a timing shift when each light spot passes through the isolated pit region _Ip , and its unit is time. Therefore, it is necessary to convert this into a unit of length. Therefore, by multiplying the measured pulse width by the linear velocity of the optical disc DK0, the moving distance corresponding to the timing difference between the two light spots is calculated. This moving distance indicates the amount of positional deviation in the circumferential direction of both light spots. In step S254, the amount of positional deviation between the two light spots is calculated in this way.

  After calculating the amount of positional deviation in the circumferential direction of both the light spots in step S254, the controller 600 records and reproduces the calculated positional deviation amount and the optical spot of the servo laser beam in step S256. The shift direction of the light with respect to the light spot is displayed on the display device 602. Here, the shift direction indicates, for example, whether the light spot of the servo laser beam is shifted in the preceding direction or the subsequent direction in the circumferential direction with respect to the light spot of the recording / reproducing laser beam. In this case (in the case of case 1 in FIG. 17), a display indicating that there is a shift in the following direction is made.

On the other hand, if it is determined in step S252 that the pulse width is larger than Δ3, the two light spots are not related to the positional deviation as shown in FIG. 2 is predicted to have a positional shift relationship as shown in FIG. Therefore, in this case, the process proceeds to step S262, and the pulse width of the second evaluation pulse signal PS _EV 2 generated by the second evaluation signal generation circuit 316 is measured in step S262. Then, in the next step S264, it is determined whether the measured pulse width is equal to or less than a predetermined width Δ4. This width Δ4 is set in the same manner as Δ3.

If it is determined in step S264 that the pulse width of the second evaluation pulse signal PS _EV 2 is Δ4 or less, the light spot of the servo laser light precedes the light spot of the recording / reproducing laser light, and both It can be seen that the circumferential displacement of the light spot is represented by the pulse width of the second evaluation pulse signal PS _EV 2. In this case, the process proceeds to step S266. Otherwise, the process proceeds to step S270.

Proceeding to step S270 means that the determination in step S252 is “No” and the determination in step S264 is also “No”. This means that both the pulse width of the first evaluation pulse signal PS _EV 1 and the pulse width of the second evaluation pulse signal PS _EV 2 are larger than the predetermined pulse width, and the light spot is isolated from the optical disc DK0. It is assumed that the reproduction signal generated when crossing the pit area _Ip was not properly input. Therefore, in this case, it is considered that some abnormality has occurred in the apparatus, so the abnormality is displayed on the display device 602 in step S270, and the execution of this program is terminated in step S272.

  If it is determined in step S264 that the pulse width is equal to or less than Δ4 and the process proceeds to step S266, the actual circumferential displacement of the servo laser light spot and the recording / reproducing laser light spot in step S266. The amount is measured (shift amount calculation step). The measurement of the circumferential positional deviation amount is performed by a method similar to the method shown in step S254 described above.

  After calculating the positional deviation amount of both the light spots in step S266, the controller 600, in step S268, calculates the positional deviation amount and the light of the recording / reproducing laser beam of the servo laser light spot. The shift direction with respect to the spot is displayed on the display device 602. Here, the deviation direction indicates, for example, whether the light spot of the servo laser beam is displaced in the preceding direction or the subsequent direction in the circumferential direction with respect to the light spot of the recording / reproducing laser beam. In this case (in case 2 of FIG. 17), a display indicating that there is a shift in the preceding direction is made.

  After displaying the positional deviation amount and the positional deviation direction of the light spot on the display device 602 in step S256 or step S268, the controller 600 determines in step S258 whether a predetermined time has elapsed. During this time, the operator operates the first laser light source 401 or the second laser light source 402 of the laser light irradiation apparatus 1, and the optical axes of the two laser lights are adjusted so that the displayed circumferential displacement amount becomes zero. Are adjusted (optical axis adjustment step, circumferential direction adjustment step). After the predetermined time has elapsed, the controller 600 proceeds to step S260, and determines whether an input indicating the end of the circumferential adjustment is input from the operator. When ending the optical axis adjustment in the circumferential direction, the operator performs an input operation indicating “end” via the input device 604. On the other hand, when the optical axis adjustment in the circumferential direction is performed again, nothing is done as it is. When controller 600 determines that an input operation indicating "end" has been performed by the operator (step S260: Yes), the process returns to step S212. If it is determined that the input operation indicating “end” has not been performed (step S260: No), the process returns to step S250, and the operations of steps S252 to S258 and / or steps S262 to S268 are repeated.

  If it is determined in step S260 that an input operation indicating “end” has been performed (step S260: Yes) and the process returns to step S212, an input request for an adjustment direction is displayed on the display device 602 in step S212. In response to the input request displayed on the display device 602, the operator adjusts the position of the light spot in the “radial direction”, the “circumferential direction” or the adjustment of the optical axis adjustment optical disk DK0. Select whether to end. Subsequently, in step S214, the controller 600 determines whether or not the adjustment direction input from the operator in response to the input request in step S212 is the “radial direction”. If it is “radial direction”, the process proceeds to step S216. If it is not “radial direction”, the process proceeds to step S244.

  When the process proceeds from step S214 to step S216, the positional deviation amount in the radial direction of both light spots is calculated based on the tracking error signal. On the other hand, when the process proceeds from step S214 to step S244, it is determined whether or not the operator inputs “end” the adjustment in response to the input request in step S212. If there is no input to end the adjustment (S244: No), it is considered that the optical axis adjustment in the circumferential direction needs to be performed again, the process proceeds to step S246, and the optical axis adjustment in the circumferential direction is performed. If there is an input to “end” the adjustment (S244: Yes), the process proceeds to step S276. In this case, it is considered that the optical axis adjustment in the radial direction and the circumferential direction has been completed, and in this step S276, the controller 600 stops emitting the laser from the first laser light source 401 and the second laser light source 402, and Shut down the various circuits and devices that were activated by the execution. In step S278, the execution of this program is terminated.

As described above, according to this embodiment, as in the first embodiment, in the radial direction on both sides of the predetermined track (isolated track area I _t), non-track area formed over a predetermined radial width (Region A portion) and a non-pit region (region B portion) formed over a predetermined circumferential length on both sides in the circumferential direction of a predetermined pit (isolated pit region I _p ) in at least one track While rotating the optical disc DK0, a plurality of laser beams are irradiated so as to pass through the isolated track region or the isolated pit region, and the reflected light from the optical disc DK0 is detected for each of the plurality of laser beams. Based on the light, a tracking error signal and a reproduction signal are generated, and on the optical disk DK0 based on the generated tracking error signal and reproduction signal of each light spot. The positional deviation of the plurality of formed light spots is detected, and the optical axes of the plurality of laser beams are adjusted based on the detected positional deviation of the plurality of light spots. According to this adjustment method, the tracking error signal generated when the light spot crosses the isolated track area and the reproduction signal generated when the light spot passes the isolated pit area can be distinguished from other signals. Therefore, signals derived from a plurality of light spots can be clearly grasped. Therefore, by adjusting the optical axes of the plurality of laser beams so that the radial positions of the light spots coincide based on the comparison result of these signals, it is possible to perform an accurate optical axis adjustment.

  Also, the tracking error signal is binarized to generate a tracking error pulse signal (transverse signal binarization step), and the reproduction signal is binarized to generate a reproduction pulse signal (passage signal binarization step). The first evaluation pulse signal, which is a pulse signal indicating the positional deviation of the plurality of light spots in the radial direction of the optical axis adjusting optical disk DK0, by comparing the tracking error pulse signals generated from the light spots of And is a pulse signal indicating the displacement of the positions of the plurality of light spots in the circumferential direction of the optical axis adjusting optical disk DK0 by comparing the reproduction pulse signals generated from the plurality of light spots. Two evaluation pulse signals are generated, and a plurality of evaluation pulse signals are generated based on the first evaluation pulse signal and the second evaluation pulse signal. It is quantitatively calculating the shift amount of the spot. For this reason, it is possible to grasp the amount of deviation quantitatively and to recognize that the optical axis has been adjusted by setting the numerical value indicating the deviation to 0.

In the present embodiment, various modifications can be made. The inter-track cross time detection circuit 320 in the above embodiment, the light spot has detected the time to move from the isolated track area I _t to the isolated track region I _t, omitting inter-track cross time detection circuit 320, a first evaluation by the use signal generating circuit 314 pulse width second evaluation signal generation circuit 316 outputs a pulse width of more that did not employ the displacement of the light spot light spot from the isolated track area I _t to the isolated track region I _t It may be time to move to. Also by this, the same effect as the above embodiment can be expected.

It is the schematic which shows the state which connected the signal evaluation apparatus to the laser beam irradiation apparatus in embodiment of this invention. 1 is a schematic front view of an optical axis adjusting optical disk used in an embodiment of the present invention. It is the schematic diagram which showed the formation state of the track formed in the laser beam irradiation surface of the optical axis adjustment optical disk, and the arrangement | positioning state of a pit. It is the schematic diagram which showed the other example of the formation state of the track | truck formed in the laser beam irradiation surface of the optical axis adjustment optical disk, and the arrangement | positioning state of a pit. It is a flowchart of the signal evaluation program in 1st embodiment of this invention. In 1st embodiment of this invention, it is a figure which shows the shape of 1st tracking error signal TE1 and 2nd tracking error signal TE2 which are projected on a digital oscilloscope. In 1st embodiment of this invention, it is a figure which shows the shape of 1st reproduction signal RS1 and 2nd reproduction signal RS2 which are projected on a digital oscilloscope. It is a figure which shows the circuit structure of the signal evaluation apparatus which concerns on 2nd embodiment of this invention. It is a figure which shows the circuit structure of the 3rd binarization circuit and 4th binarization circuit which concern on 2nd embodiment of this invention. It is a figure which shows the circuit structure of the crossing time detection circuit between tracks which concerns on 2nd embodiment of this invention. It is a figure which shows the waveform of the tracking error signal from which a zero crossing point detection signal, a track crossing detection signal, and a mask signal are output. It is a figure which shows the waveform of the tracking error signal from which a mask signal is output first and a zero cross point detection signal and a track crossing detection signal are not output. It is a flowchart of the signal evaluation program which concerns on 2nd embodiment of this invention. It is a flowchart of the signal evaluation program which concerns on 2nd embodiment of this invention. It is a flowchart of the signal evaluation program which concerns on 2nd embodiment of this invention. It is a figure which shows the signal waveform of the tracking error signal, tracking error pulse signal, and evaluation pulse signal output according to the positional relationship (case 1, case 2) of a light spot. It is a figure which shows the signal waveform of the reproduction | regeneration signal, reproduction | regeneration pulse signal, and evaluation pulse signal output according to the positional relationship (case 1, case 2) of a light spot.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Laser beam irradiation apparatus, 110 ... Second tracking error signal generation circuit, 116 ... Second reproduction signal generation circuit, 122 ... First tracking error signal generation circuit, 124 ... First reproduction signal generation circuit, 300 ... Signal evaluation apparatus , 302... First binarization circuit (first pulse signal generation means)
304 ... second binarization circuit (second pulse signal generation means), 306 ... third binarization circuit (first pulse signal generation means), 308 ... fourth binarization circuit (second pulse signal generation means) 314 ... first evaluation signal generation circuit (evaluation pulse signal generation means), 316 ... second evaluation signal generation circuit (evaluation pulse signal generation means), 318 ... pulse width measurement device (pulse width measurement means), 320 ... Cross-track time detection circuit (radial speed specifying means), 401 ... first laser light source, 402 ... second laser light source, 410 ... first photo detector, 413 ... second photo detector, 600 ... controller, A ... no track Area, B ... No pit area, DK0 ... Optical axis adjusting optical disk, I _p ... Isolated pit area, I _t ... Isolated track area, RS1 ... First reproduction signal, RS2 ... Second reproduction signal , TE1 ... first tracking error signal, TE2 ... second tracking error signal, PS _RS 1 ... first reproduction pulse signal, PS _RS 2 ... second reproduction pulse signal, PS _TE 1 ... first tracking error pulse signal, PS _TE 2 ... second tracking error pulse signal, PS _EV 1 ... first evaluation pulse signal, PS _EV 2 ... second evaluation pulse signal, PUH ... optical pickup device

Claims (14)

For a laser light irradiation apparatus that irradiates an optical disc with a plurality of laser beams to form a light spot on the optical disc and generates a signal by receiving reflected light from the optical disc irradiated with the plurality of laser beams An optical axis adjustment method for adjusting the optical axes of the plurality of laser beams so that the positions of the plurality of light spots formed on the optical disc coincide with each other,
An optical axis adjusting optical disc in which tracks are formed along a circumferential direction in at least a predetermined radial region and pits are formed in the track, and the optical axis adjusting optical disc has predetermined Rotating an optical disc having a track-free area formed over a radial width of the track and a pit-free area formed over a predetermined circumferential length on both sides of a predetermined pit or group of pits in at least one track A laser beam irradiation step of irradiating a plurality of laser beams so as to cross the predetermined track or group of tracks and pass through the predetermined pit or group of pits;
A signal generation step of detecting reflected light of the plurality of laser beams irradiated to the optical axis adjusting optical disc in the laser beam irradiation step for each of the plurality of laser beams, and generating a signal based on the reflected light, respectively;
A deviation detecting step of detecting deviations of a plurality of light spots formed on the optical axis adjusting optical disc based on the signal generated for each reflected light in the signal generating step;
An optical axis adjustment step of adjusting the optical axes of the plurality of laser beams based on the deviations of the plurality of light spots detected in the deviation detection step;
An optical axis adjustment method comprising: The optical axis adjustment method according to claim 1,
The deviation detection step detects deviations of a plurality of light spots formed on the optical axis adjusting optical disk based on the generation timing of the signal generated for each reflected light in the signal generation step. And an optical axis adjustment method. In the optical axis adjustment method according to claim 1 or 2,
The signal generation step includes:
Generating a crossing signal for generating a crossing signal that is generated when a light spot of the plurality of laser lights crosses the predetermined track or group of tracks;
A passing signal generating step for generating a passing signal generated when the light spots of the plurality of laser beams pass through the predetermined pit or pit group;
An optical axis adjustment method comprising: In the optical axis adjustment method according to claim 3,
The optical axis adjustment step includes
A radial direction adjusting step of adjusting the optical axes of the plurality of laser beams so that the positions of the plurality of light spots in the radial direction of the optical axis adjusting optical disk coincide with each other based on the crossing signal;
A circumferential direction adjusting step of adjusting the optical axes of the plurality of laser beams so that the positions of the plurality of light spots in the circumferential direction of the optical axis adjusting optical disc are matched based on the passing signal;
An optical axis adjustment method comprising: In the optical axis adjustment method according to any one of claims 1 to 4,
The optical axis adjustment method, wherein the shift detection step includes a display step for displaying a plurality of signals generated in the signal generation step. In the optical axis adjustment method according to any one of claims 1 to 4,
The deviation detection step includes:
A signal comparison step of comparing a plurality of signals generated for each reflected light in the signal generation step;
A deviation amount calculating step for calculating a deviation amount of a plurality of light spots based on the comparison result in the signal comparison step;
An optical axis adjustment method comprising: In the optical axis adjustment method according to claim 3 or 4,
The deviation detection step includes:
A crossing signal comparison step of comparing a plurality of crossing signals generated in the crossing signal generation step;
A passage signal comparison step for comparing a plurality of passage signals generated in the passage signal generation step;
A deviation amount calculating step for calculating the deviation amount based on comparison results in the crossing signal comparison step and the passing signal comparison step;
An optical axis adjustment method characterized by comprising: In the optical axis adjustment method according to claim 7,
The deviation detection step includes a crossing signal binarization step that binarizes the crossing signal generated in the crossing signal generation step into a pulse signal, and a binary value of the passing signal generated in the pass signal generation step. Further comprising a pass signal binarization step that is converted into a pulse signal,
In the crossing signal comparison step, based on the pulse signal generated in the crossing signal binarization step, crossing signal evaluation that is a pulse signal indicating a deviation of a plurality of light spots in the radial direction of the optical axis adjusting optical disk A pulse signal for
In the pass signal comparison step, based on the pulse signal generated in the pass signal binarization step, the pass signal evaluation is a pulse signal indicating a deviation of a plurality of light spots in the circumferential direction of the optical axis adjusting optical disc A pulse signal for
The optical axis adjustment method, wherein the deviation amount calculating step calculates the deviation amount based on the crossing signal evaluation pulse signal and the passing signal evaluation pulse signal. The optical axis adjustment method according to claim 8, wherein
The deviation detecting step includes a linear velocity specifying step of specifying a linear velocity of a light spot formed on the optical axis adjusting optical disc with respect to the optical axis adjusting optical disc when the optical axis adjusting optical disc is rotating. A cross-track crossing time detecting step of detecting a time during which the light spot crosses from the predetermined track or track group to an adjacent predetermined track or track group;
The shift amount calculating step includes a pulse width of the crossing signal evaluation pulse signal, a pulse width of the passing signal evaluation pulse signal, the linear velocity specified in the linear velocity specifying step, and the crossing time between tracks. A method of adjusting an optical axis, comprising: calculating a positional shift amount of the plurality of light spots on the optical disk based on the crossing time between tracks detected in the step. For a laser light irradiation apparatus that irradiates an optical disc with a plurality of laser beams to form a light spot on the optical disc and generates a signal by receiving reflected light from the optical disc irradiated with the plurality of laser beams In the deviation detection device for detecting deviations of a plurality of light spots formed on the optical disc,
A first pulse signal generating means for generating a first pulse signal by inputting a signal based on reflected light from a first light spot formed on the optical disc and binarizing the input signal;
A second pulse signal generating means for generating a second pulse signal by inputting a signal based on the reflected light from the second light spot formed on the optical disc and binarizing the input signal;
The first pulse signal and the second pulse signal are input, and the first pulse signal and the second pulse signal cause a positional deviation between the first light spot and the second light spot. An evaluation pulse signal generating means for generating an evaluation pulse signal that becomes a high level or a low level when the predetermined relationship is expressed and becomes a low level or a high level when the relationship is other than the predetermined relationship;
Pulse width measuring means for measuring the pulse width of the high level portion or the low level portion of the pulse signal for evaluation;
A deviation detecting device comprising: The deviation detecting apparatus according to claim 10, wherein
Linear velocity specifying means for specifying a linear velocity of the optical spot with respect to the optical disc when the optical disc on which a plurality of optical spots are formed is rotating;
A radial velocity specifying means for specifying a radial velocity of the optical spot with respect to the optical disc when the optical disc is rotating;
Based on the pulse width measured by the pulse width measuring unit, the linear velocity specified by the linear velocity specifying unit, and the radial velocity specified by the system direction velocity specifying unit, a plurality of light spots on the optical disc A positional deviation amount measuring means for measuring the positional deviation amount;
The deviation detecting device further comprising: In the deviation detection device according to claim 10 or 11,
The optical disc is
For a laser light irradiation apparatus that irradiates an optical disc with a plurality of laser beams to form a light spot on the optical disc and generates a signal by receiving reflected light from the optical disc irradiated with the plurality of laser beams An optical axis adjusting optical disc for adjusting optical axes of the plurality of laser beams so that positions of a plurality of light spots formed on the optical disc coincide with each other,
An optical axis adjusting optical disc in which tracks are formed along a circumferential direction in at least a predetermined radial region and pits are formed in the track, and the optical axis adjusting optical disc has predetermined A track-free region formed across the radial width of
A non-pit area formed over a predetermined circumferential length on both sides in a circumferential direction of a predetermined pit or pit group in at least one track;
An optical axis adjusting optical disk on which is formed. For a laser light irradiation apparatus that irradiates an optical disc with a plurality of laser beams to form a light spot on the optical disc and generates a signal by receiving reflected light from the optical disc irradiated with the plurality of laser beams An optical axis adjusting optical disc for adjusting optical axes of the plurality of laser beams so that positions of a plurality of light spots formed on the optical disc coincide with each other,
An optical axis adjusting optical disc in which tracks are formed along a circumferential direction in at least a predetermined radial region and pits are formed in the track, and the optical axis adjusting optical disc has predetermined A track-free region formed across the radial width of
A non-pit area formed over a predetermined circumferential length on both sides in a circumferential direction of a predetermined pit or pit group in at least one track;
An optical axis adjusting optical disc on which is formed. In the optical axis adjustment method according to any one of claims 1 to 9,
The method of adjusting an optical axis, wherein the laser beam irradiation device is an optical disc device that records data on an optical disc or reproduces data recorded on the optical disc.

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