JP4205023B2 - Optical pickup position adjusting method and optical pickup position adjusting apparatus - Google Patents

Description

  The present invention relates to an optical pickup position adjusting method and an optical pickup position adjusting apparatus in an optical disc apparatus that adjusts the relative positional relationship between an optical pickup and a center line passing through a rotation axis of an optical recording medium.

  In an optical disc apparatus, a plurality of spots are collected on a recording surface of an optical recording medium (optical disc), and an optical pickup using a system that generates a servo signal and an information reproduction signal from the reflected light, and those spots are provided. An optical pickup that records information by using it is mounted. These optical pickups mounted on the optical disk apparatus are used for recording, reproducing, erasing information and generating servo signals on an optical recording medium.

  Therefore, when the optical pickup mounting position is deviated, the spot is not arranged at a predetermined position on the optical recording medium, which causes the occurrence of a track offset and a decrease in the amplitude of the tracking error signal. For this reason, it is necessary to accurately adjust the mounting position of the optical pickup, which is one problem when the optical pickup is incorporated into the optical disc apparatus.

  Here, a differential push-pull method (hereinafter referred to as “DPP method”), which is one of well-known tracking methods used in optical disc apparatuses, will be described. The DPP method is a tracking method in which a diffraction grating is installed in an optical path from a light source to an optical recording medium, and zero-order light (transmitted light) is a main beam, ± first-order light is a sub-beam, and three beams are used.

  In the DPP method, at the time of tracking, the sub beam is arranged at a position shifted by m / 2 tracks (m is an odd number) with respect to the main beam. A phase shift of 180 ° occurs between a “main push-pull signal” and a push-pull signal by a sub-beam (hereinafter referred to as “sub-push-pull signal”).

  Therefore, when the amplitudes of the main push-pull signal and the sub push-pull signal are equalized and subtracted, the DC component (offset) is canceled and a tracking error signal whose amplitude is doubled is obtained. That is, the offset of the tracking error signal generated by the normal push-pull method does not occur (cancel) due to the positional deviation of the objective lens and the light receiving element.

  However, when the optical pickup is mounted on the optical disc apparatus, a mounting error occurs, and the DC beam is shifted when the sub beam is shifted from a predetermined position, that is, a position shifted by m / 2 tracks with respect to the main beam. The component cannot be canceled and a residual offset occurs. In addition, the amplitude of the tracking error signal may be reduced, and the tracking control may be seriously affected.

  Further, when the relative position between the optical pickup and the spindle motor shaft is not adjusted, and the main beam and the sub beam are not arranged near the same track, when the phase change recording medium is used, the reproduction signal is not There is a problem in that a tracking error signal is offset due to a change in reflectance between the recorded area and the unrecorded area at the boundary between the recorded area and the unrecorded area where the reproduction signal is not recorded.

  Therefore, as a method for mounting an optical pickup adjusted so that a sub beam is arranged on a specific track on a spindle motor for rotating the optical recording medium and a mechanism for sending the optical recording medium in the radial direction, Patent Literature No. 1 proposes a method in which the optical recording medium is adjusted to the optimum position on the basis of the sub-signal waveform represented by the sum of the DPP signal and the push-pull signal of each sub-beam every rotation.

  The prior art described in Patent Document 1 will be described with reference to FIGS. 15 and 16. FIG. 15 is a bottom view of the optical disc apparatus 100 with the normal deviation adjusting device 110 attached. The normal line deviation of the turntable 103 rotated by the spindle motor is automatically adjusted. Here, the normal deviation is a deviation in the relative position between the optical pickup 101 and the turntable 103 due to an attachment error of the turntable 103 or the like.

  In the optical disc apparatus 100, the turntable 103 disposed on the chassis 104 is movable in a direction orthogonal to the guide shaft 102 in a horizontal plane, and the optical pickup 101 performs optical recording along the guide shaft 102. It is provided so as to be movable in the radial direction of a medium (disk; not shown).

  Subsequently, a procedure for adjusting the normal deviation will be described. First, the optical pickup 101 is opposed to the outer periphery of the rotating disk, and focus servo is applied. Next, the control circuit 112 detects the DPP signal, and if a normal deviation occurs, the waveform of the DPP signal is wavy as shown in FIG. The position of the turntable 103 is roughly adjusted using the DPP signal at.

  Specifically, the DPP signal waveform for each rotation of the disk and the movement amount of the turntable 103 are sequentially stored in the memory 113 while the turntable 103 is moved little by little. From the information in the memory 113, the control circuit 112 finds a place where the level of the DPP signal is maximized and the swell is reduced, and sends a signal for energizing the motor 115 to the power feeding circuit 114, and turns the turntable 103 to this place. Move to.

  Next, the optical pickup 101 is moved so that the optical pickup 101 faces the inner periphery of the rotating disk, and focus servo is applied. Then, the position of the turntable 103 is adjusted using the DPP signal in the inner periphery of the disk.

  That is, while the turntable 103 is moved little by little, the waveform of the DPP signal for each rotation of the disk and the amount of movement of the turntable 103 are sequentially stored in the memory 113. A location where the level of the DPP signal is maximized and the swell is reduced is found, and the motor 115 is energized from the power supply circuit 114 to move the turntable 103 to this location. The optical pickup 101 is opposed to the inner periphery of the disc because the radius of curvature of the track is smaller in the inner periphery of the disc than in the outer periphery, so that the main beam and the sub beam are accurate even if a slight normal deviation occurs. This is because it is out of position. By making the optical pickup 101 face the inner peripheral portion of the disk, it becomes possible to adjust with higher accuracy than the coarse adjustment.

  Next, the position of the turntable 103 is finely adjusted using a sub signal (sub-beam push-pull signal) with the pickup 101 facing the inner periphery of the disk. The waveform of the sub-signal waveform shown in FIG. 16B, that is, a position where the difference between the maximum value and the minimum value of the amplitude is minimized, and the turntable 103 is moved to this position.

  As shown in FIGS. 16 (a) and 16 (b), since the sub signal undulates with a half period of the DPP signal, the shape of the peak or valley of the sub signal is sharper than the shape of the peak or valley of the DPP signal. Therefore, if the adjustment is performed by observing the peak or valley of the sub-signal, fine adjustment is easier than the adjustment using the DPP signal, and the adjustment can be performed with higher accuracy.

  As described above, in Patent Document 1, the normal deviation is adjusted in order from the wide adjustment range to the narrow adjustment range, and the adjustment accuracy is improved by using the sub signal.

Further, the applicant of the present application has previously proposed a method that can be applied as an adjustment-less method in which the relative positional relationship between the optical pickup and the spindle motor is not adjusted as Patent Document 2. According to this, as shown in FIG. 17, a diffraction grating 122 having a configuration in which the grating groove interval in a part of the region 122 is shifted by 1/2 pitch from the other region 121 is used. When the diffraction grating 122 is used, the signal amplitude of the sub push-pull signal is almost 0. Therefore, when the DPP method is applied, the positional relationship between the main spot and the sub spot with respect to the track groove of the optical recording medium. There are no restrictions. As a result, the present invention can be applied without adjustment without adjusting the relative positional relationship between the optical pickup and the spindle motor without causing fluctuations in the amplitude of the DPP signal and track offset.
JP 2002-50064 A (published on February 15, 2002) JP 2001-250250 A (published September 14, 2001)

  However, in the adjustment method of the optical disc apparatus of Patent Document 1, after adjustment is performed at the outer peripheral portion of the optical recording medium, further adjustment is performed at the inner peripheral portion, so that the adjustment process increases and adjustment takes time. is there. Further, since it is necessary to measure the undulation of the sub-signal amplitude together with the undulation of the DPP signal amplitude for adjustment, there is a problem that the number of measurement items necessary for the adjustment increases.

  In addition, since the sub-signal, that is, the sub-beam push-pull signal, is used for fine adjustment, a diffraction grating having a signal amplitude of the sub-push-pull (SPP) signal of 0 is used, and the sub-push-pull component is not generated. The optical pickup as described in Document 2 cannot implement the adjustment method of Patent Document 1.

  The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to provide an optical pickup including a diffraction grating in which the amplitude of a sub push-pull signal is almost zero. It is an object of the present invention to provide an optical pickup position adjustment method and an optical pickup position adjustment apparatus capable of easily and accurately adjusting the relative position between the pickup and the rotation axis of the optical recording medium with a small number of steps.

  In order to achieve the above object, the optical pickup position adjusting method according to the present invention includes the optical pickup and the rotation so that the optical pickup is disposed on a predetermined center line passing through the rotation axis of the optical recording medium. An optical pickup position adjusting method for adjusting a relative position with respect to an axis, wherein the optical pickup divides light emitted from a light source into three beams of zero-order light and ± first-order light. A diffraction grating in which the amplitude of the push-pull signal of the ± 1st-order light obtained from the recording medium is approximately 0 so that the spots of the 0th-order light and ± 1st-order light are arranged on the same track in the optical recording medium. The above three beams are subjected to focus control on an optical recording medium which is arranged and includes a recording area where a reproduction signal is recorded and an unrecorded area where no reproduction signal is recorded. The position of the optical pickup and the rotating shaft is adjusted by using a signal detected by a two-divided detector which is substantially divided into two along the track direction with respect to at least one of the reflected lights. It is said.

  Since the recording area and the non-recording area have different light reflectivities, if the optical pickup is disposed on the center line passing through the rotation axis of the optical recording medium, the zero-order light and the ± first-order light The time required for each spot to pass through the boundary between the recording area and the unrecorded area is the same, but when the optical pickup is not arranged on the center line, the spots of the 0th order light and ± 1st order light are recorded in the recording area. There will be a difference in the time required to pass the boundary between the unrecorded area and the unrecorded area. Therefore, by using the difference in the passing time of each spot and adjusting the relative position between the optical pickup and the rotating shaft so as not to cause a difference in the passing time, it is determined in advance through the rotating shaft of the optical recording medium. An optical pickup can be arranged on the center line.

  In the adjustment method using the sub push-pull signal which is the push-pull signal of ± 1st order light for the adjustment, the position of the optical pickup having the diffraction grating in which the amplitude of the sub push-pull signal is almost zero cannot be adjusted. However, this makes it possible to adjust the position even with an optical pickup having a diffraction grating in which the amplitude of the sub push-pull signal is almost zero. In addition, as will be described later in detail, for example, adjustment can be performed by observing a Lissajous waveform.

  Further, since the amplitude of the sub push-pull signal is almost zero, it is hardly affected by the radius of curvature of the optical recording medium. As a result, any radius of the optical recording medium can be obtained without moving the optical pickup from the outer periphery to the inner periphery. Adjustment is possible even at the position, and there are few adjustment steps and accuracy is good.

  Therefore, even with an optical pickup equipped with a diffraction grating in which the amplitude of the sub push-pull signal is almost zero, the relative position between the optical pickup and the rotation axis of the optical recording medium can be adjusted easily with a small number of processes. Can be done.

  Three beams are focus-controlled on an optical recording medium composed of a recording area and an unrecorded area, and at least any one of ± primary light obtained at that time is substantially divided into two along the track direction. The following method can be considered as a method of detecting with a two-divided detector and adjusting using the detection signal.

  For example, in the optical recording medium, the recording area and the non-recording area are periodically and repeatedly provided in the optical recording medium, and the reflected light of the + 1st order light is detected by the first two-divided detector. Using the sum signal obtained by detection and the sum signal obtained by detecting the reflected light of the −1st order light with the second two-divided detector, the two sum signals have the same phase. The position of the optical pickup and the rotation shaft are adjusted. This pays attention to the difference in the passing time of each spot of ± primary light.

  Further, in the optical recording medium, the recording area and the non-recording area are provided periodically and obtained by detecting any one of the ± primary reflected light with a two-divided detector. And the sum signal obtained by detecting the reflected light of the 0th order light with a third two-divided detector, so that the two sum signals have the same phase, The position is adjusted with respect to the rotation shaft. This pays attention to the difference in transit time between each spot of ± first-order light and spot of zero-order light.

  Further, in the optical recording medium, the recording area and the non-recording area are provided periodically and any one obtained by detecting the reflected light of the + 1st order light with the first two-divided detector. These two output signals have the same phase using either one of the output signals and one of the output signals obtained by detecting the reflected light of the −1st order light with the second two-divided detector. As described above, the position of the optical pickup and the rotation shaft may be adjusted. This also pays attention to the difference in the passing time of each spot of ± 1st order light, but since it is not necessary to obtain the sum signal, the circuit configuration for adjusting the optical pickup is made more than the method using the sum signal. It can be simplified.

  Further, a sum signal obtained by detecting the reflected light of the + 1st order light with the first two-divided detector and a sum obtained by detecting the reflected light of the −1st order light with the second two-divided detector. The position of the optical pickup and the rotation shaft is adjusted so that the sum signal of these two sum signals changes sharply at the boundary between the recorded area and the unrecorded area. Also good. This also pays attention to the difference in the passing time of each spot of ± 1st order light, but does not compare the phase of the signal, so there is no need to convert it to a Lissajous waveform or the like, and the signal (two sum signals) The sum signal) can be adjusted as it is.

  Further, it is obtained by detecting the push-pull signal obtained by detecting the reflected light of the + 1st order light with the first two-divided detector and the reflected light of the −1st order light with the second two-divided detector. Using the push-pull signal, the sum signal of these two push-pull signals adjusts the position of the optical pickup and the rotary shaft so that no offset occurs at the boundary between the recorded area and the unrecorded area. You may do it. This also pays attention to the difference in passing time of each spot of ± 1st order light, but has an additional advantage that it can cope with the offset of the sum signal of each sub push-pull signal of 1st order light.

  In other words, even if a diffraction grating in which the amplitude of the push-pull signal of ± first-order light is approximately 0 is used due to a processing error in the groove interval of the diffraction grating, an aperture limit of an objective lens mounted on the optical pickup, etc. The push-pull signal amplitude of the primary light may not be almost zero. In such a case, if the optical pickup is arranged on the center line passing through the rotation axis of the optical recording medium, an offset does not occur in the sum signal of each sub push-pull signal of ± primary light, but the optical pickup is in the center. If it is not arranged on the line, an offset occurs in the sum signal. Such an offset of the sum signal of the sub push-pull signals of ± 1st order light gives an offset to the differential push-pull signal, so that stable tracking control cannot be performed.

  However, as described above, the sum signal of the sub push-pull signals of ± 1st order light does not generate an offset at the boundary between the recording area and the unrecorded area. By performing the position adjustment, in addition to the position adjustment of the optical pickup, the offset of the differential push-pull signal can be eliminated, and stable tracking control can be performed.

  Further, it is obtained by detecting the push-pull signal obtained by detecting the reflected light of the + 1st order light with the first two-divided detector and the reflected light of the −1st order light with the second two-divided detector. Using the differential push-pull signal obtained by using the push-pull signal and the push-pull signal obtained by detecting the reflected light of the zero-order light with the third two-divided detector, the recorded area and the unrecorded area Position adjustment of the optical pickup and the rotating shaft so that the positive side amplitude and the negative side amplitude of the differential push-pull signal at the boundary with the region are equal to an optimum value that does not cause a tracking error May be performed. This also pays attention to the difference in the passing time of each spot of ± 1st-order light, and can also cope with the offset of the sum signal of each sub push-pull signal of ± 1st-order light as described above.

  As described above, when the sum signal of the sub push-pull signals of ± 1st order light is offset at the boundary between the recording area and the unrecorded area, an offset is generated in the differential push-pull signal. Therefore, as described above, the positive side amplitude and the negative side amplitude of the differential push-pull signal at the boundary between the recording area and the non-recording area are made equal to the optimum value that does not cause a tracking error. By adjusting the position of the optical pickup and the rotating shaft, in addition to the adjustment of the position of the optical pickup, the offset of the differential push-pull signal can be eliminated, and stable tracking control can be performed. In addition, the differential push-pull signal can be directly used for adjustment.

  In order to solve the above-described problem, the optical pickup position adjusting device of the present invention is a diffraction grating that divides light emitted from a light source into three beams of zero-order light and ± first-order light. A diffraction grating in which the amplitude of the push-pull signal of the ± 1st-order light obtained from the medium is approximately 0 is arranged so that the spots of the 0th-order light and ± 1st-order light are arranged on the same track in the optical recording medium. Position adjustment of the optical pickup that adjusts the relative position of the optical pickup and the rotation axis so that the installed optical pickup is arranged on a predetermined center line passing through the rotation axis of the optical recording medium The above-mentioned three beams are focus-controlled on an optical recording medium composed of a recording area in which a reproduction signal is recorded and an unrecorded area in which no reproduction signal is recorded. Small A deviation amount detection for detecting a deviation amount between the optical pickup and the center line using a signal detected by a two-divided detector which is substantially divided into two along the track direction. And an adjusting means for adjusting the relative position between the optical pickup and the rotating shaft based on the deviation amount detected by the deviation amount detecting means.

  According to this, the deviation amount detecting means controls the focus of the three beams on the optical recording medium composed of the recording area where the reproduction signal is recorded and the unrecorded area where the reproduction signal is not recorded. The amount of deviation between the optical pickup and the center line is determined by using a signal obtained by detecting a reflected light of at least one of ± primary lights with a two-divided detector substantially divided into two along the track direction. The detecting and adjusting means adjusts the relative position between the optical pickup and the rotating shaft based on the deviation amount detected by the deviation amount detecting means.

  Therefore, as already described as the method of adjusting the position of the optical pickup, even if the optical pickup includes a diffraction grating in which the amplitude of the sub push-pull signal is substantially zero, the optical pickup and the rotation axis of the optical recording medium The relative position can be adjusted easily and accurately with a small number of steps.

  As described above, the optical pickup position adjusting method according to the present invention is configured so that the optical pickup and the rotation axis are relatively positioned so that the optical pickup is disposed on a predetermined center line passing through the rotation axis of the optical recording medium. A method for adjusting the position of an optical pickup that adjusts the position of the optical pickup. In the optical pickup, the light emitted from the light source is divided into three beams of zero-order light and ± first-order light, and is obtained from the optical recording medium. A diffraction grating in which the amplitude of the push-pull signal of the ± 1st order light is approximately 0 is arranged so that the spots of the 0th order light and the ± 1st order light are arranged on the same track in the optical recording medium. The three beams are focus-controlled on an optical recording medium composed of a recording area where a reproduction signal is recorded and an unrecorded area where no reproduction signal is recorded, and at least ± primary light obtained at that time The displacement or the other of the reflected light, by using a signal detected by the two divided bisected detector substantially along the track direction, is performed the position adjustment between the optical pickup and the rotating shaft.

  The position adjustment device for an optical pickup according to the present invention is a diffraction grating that divides light emitted from a light source into three beams of zero-order light and ± first-order light, and the ± first-order obtained from the optical recording medium. An optical pickup in which a diffraction grating in which the amplitude of an optical push-pull signal is approximately 0 is arranged so that the spots of the 0th order light and ± 1st order light are arranged on the same track in the optical recording medium, An optical pickup position adjusting device for adjusting a relative position between the optical pickup and the rotary shaft so as to be arranged on a predetermined center line passing through the rotary shaft of the optical recording medium, wherein a reproduction signal is The above three beams are focus-controlled on an optical recording medium consisting of a recorded area and an unrecorded area where no reproduction signal is recorded, and at least one of the reflected lights of ± primary light obtained at that time A deviation amount detecting means for detecting a deviation amount between the optical pickup and the center line using a signal detected by a two-divided detector substantially divided into two along the track direction; and the deviation amount detecting means. And adjusting means for adjusting the relative position between the optical pickup and the rotating shaft based on the amount of deviation detected in (1).

  According to the above configuration, even in an optical pickup including a diffraction grating in which the amplitude of the sub push-pull signal is substantially zero, the adjustment of the relative position between the optical pickup and the rotation axis of the optical recording medium can be performed by adjusting the number of steps. There is an effect that it can be performed easily and accurately with few.

[First Embodiment]
An embodiment according to the present invention will be described below with reference to FIGS.

  An optical disc apparatus (this apparatus) 1 according to the present embodiment is an apparatus that can write and read information by irradiating an optical disc (optical recording medium) such as a CD or DVD with light.

  As shown in FIG. 1, the apparatus 1 includes an optical pickup 2 for recording and reproducing signals by irradiating light onto an optical recording medium, and a guide for moving the optical pickup 2 in the radial direction of the optical recording medium. A mechanism unit 3 in which the unit 5 is incorporated, a spindle motor 4 for rotating the optical recording medium, an adjustment spring 6, an adjustment screw 7, and a housing 8 in which they are incorporated are provided. In FIG. 1, the rotation axis P of the spindle motor 4 is indicated by the intersection of alternate long and short dash lines L1 and L2. L1 is a center line passing through the rotation axis of the optical recording medium.

  As shown in FIG. 2, the optical pickup 2 includes a semiconductor laser 11 as a light source that emits light, a collimator lens 12 that makes light emitted from the semiconductor laser 11 substantially parallel, and 3 A diffraction grating 13 that divides the beam, a beam splitter 14 that is an optical branching unit, an objective lens 15 that is a condensing unit that condenses light emitted from the semiconductor laser 11 on the optical recording medium 16, and an optical recording medium 16 A reflected light condensing lens 17 for condensing the light reflected by the light beam, a cylindrical lens 18 for providing astigmatism for defocus detection, and a photodetector 19 including a plurality of light receiving elements.

  In the recordable optical recording medium 16, signals are recorded on the optical recording medium 16 by the semiconductor laser 11. The diffraction grating 13 generates diffracted light, passes through the beam splitter 14 and the objective lens 15, and enters the main spot MB of zero-order light (hereinafter referred to as “main beam”) and ± first-order diffracted light (hereinafter referred to as “main beam”). , “First and second sub-beams”) (see FIG. 5).

  On the other hand, the reflected light from the optical recording medium 16 has its optical path bent by the beam splitter 14, condensed by the reflected light condensing lens 17, and given astigmatism for detecting defocus by the cylindrical lens 18. It is guided to the detector 19.

  As shown in FIG. 3, the photodetector 19 includes a quadrant detection area 40 for the main beam, and first and second split detection areas 41 and 42 for the first and second sub beams. ing. Each region detects light independently, and outputs a signal corresponding to the light receiving sensitivity of each element provided separately in each region.

  FIG. 3 shows details of the diffraction grating 13. As shown in this figure, the diffraction grating 13 is added with a phase difference between the first and second sub-beams (a region 13a where no phase difference is added to the first and second sub-beams) and with the first and second sub-beams. Area (hatching area in the drawing) 13b is provided, and the area for adding the phase difference to the first and second sub-beams to the area 13a to which the phase difference is not added to the first and second sub-beams. 13b has a structure in which the lattice groove interval is shifted by 1/2 pitch.

  As a result, signal amplitudes of sub push-pull signals SPP1 and SPP2, which will be described later, output from the first and second two-divided detection areas 41 and 42 for the first and second sub-beams in the photodetector 19, respectively. It is possible to obtain a signal that is substantially zero. If the amplitude of the sub push-pull signal is approximately 0, the configuration of the diffraction grating 13 is not limited to the configuration of FIG.

  Note that the adjustment spring 6 and the adjustment screw 7 shown in FIG. 1 move the mechanism portion 3 in the direction indicated by the arrow A with respect to the housing 8, so that the optical pickup mounted on the mechanism portion 3. It is possible to adjust the mounting position of 2. Briefly, the mechanism portion 3 is biased to the housing 8 via the adjustment spring 6 so that the position of the optical pickup 2 in the arrow A direction is adjusted according to the screwing depth of the adjustment screw 7. It has become. Here, the adjustment spring 6 has a role of fixing the mechanism portion 3 to the housing 8 by expansion and contraction of the spring.

  In addition, the apparatus 1 is configured to adjust the mounting position of the optical pickup 2 by adjusting the mechanism unit 3, but there is an error in the relative position between the optical pickup 2 and the spindle motor 4 (or the optical recording medium 16). Therefore, the adjustment may be performed by moving the spindle motor 4 side.

  Next, a method for detecting the tracking error signal (DPP signal) of the optical pickup 2 by the DPP method (differential push-pull method) will be described. However, here, a case will be described in which the optical recording medium 16 is an optical recording medium for adjustment (hereinafter referred to as an adjustment medium) 50 described later, and a DPP signal is detected by the adjustment medium 50.

  The light irradiated from the semiconductor laser 11 and separated into three beams by the diffraction grating 13 is irradiated to the adjustment medium 50 as the optical recording medium 16 through the objective lens 15 as shown in FIG. The groove portion 51 and the land portion 52 are formed in the optical recording medium 16 as well as the adjustment medium 50, and the information reproduction signal is recorded in the groove portion 51 or the land portion 52. 5 shows the case where the information reproduction signal is recorded in the groove part 51, but the present invention is not limited to this, and the information reproduction signal may be recorded in the land part 52.

  In FIG. 5, three circles (MB, SB1, SB2) indicated by solid lines indicate that the mounting position of the optical pickup 2 is adjusted with high accuracy, and the optical pickup 2 indicates the rotation axis P of the spindle motor 4. 3 shows a spot of three beams when it is arranged on a one-dot chain line (hereinafter referred to as “the center line of the spindle motor 4”; a center line passing through the rotation axis of the optical recording medium) L1. MB is a spot of the main beam (main spot), and SB1 and SB2 are spots of the first and second sub beams (first and second sub spots), respectively.

  A portion where the main beam is irradiated and the main spot MB is formed is an information track. By tracking control, the irradiation position of the main beam is controlled so that the main beam irradiates the center of the information track. At this time, the first and second sub beams are irradiated to the same track as the track on which the main spot MB is formed, and the first and second sub spots SB1 and SB2 are formed on the same track. Have been adjusted.

  On the other hand, in FIG. 5, three circles (MB ′, SB1 ′, SB2 ′) indicated by broken lines indicate that the optical pickup 2 is not disposed on the center line L1 of the spindle motor 4 and the center line L1. A three-beam spot is shown when it is mounted with a shift of ΔY in a substantially orthogonal direction. The main spot and the first and second sub-spots having the deviation ΔY are indicated as MB ′, SB1 ′, and SB2 ′, respectively. As shown in FIG. 5, when the mounting position of the optical pickup 2 is shifted, the main spot MB ′ is formed in the first sub spot SB1 ′ among the first and second sub spots SB1 ′ and SB2 ′. The second sub-spot SB2 ′ is formed so as to protrude from the track on which the main spot MB ′ is formed to the inner periphery side.

  Then, as shown in FIG. 3, the diffraction pattern of the reflected light of the main beam is received by a four-divided detection region (four-divided detector) 40. In the quadrant detection area 40, the light receiving element is divided into four along the track direction (track extending direction) and the direction orthogonal to the track direction (track arrangement direction = radial direction) to form areas A, B, C, and D. is doing.

Assuming that the output signals output from the regions A, B, C, and D according to the amount of received light are also A, B, C, and D, the main push-pull signal MPP obtained from the reflected light of the main beam is MPP = (A + D )-(B + C). The main total signal MPP _SUM indicating the total amount of light received in the four-divided detection area 40 is detected by the calculation of MPP _SUM = (A + B + C + D).

  The diffraction patterns of the reflected light of the first and second sub-beams are received by first and second two-divided detection areas (two-divided detectors) 41 and 42 each having a dividing line in the track direction. In the first and second two-divided detection areas 41 and 42, the light receiving element is divided into two along the track direction, thereby forming areas E and F and areas G and H. If the output signals output from the areas E, F, G, and H according to the amount of received light are also E, F, G, and H, the difference signals from the first and second divided detection areas 41 and 42, that is, The first and second sub push-pull signals SPP1 and SPP2 are detected by the calculation of SPP1 = EF and SPP2 = GH.

Each sum signal from the first and second two-divided detection areas 41 and 42 (a signal indicating the total amount of received light in the first and second two-divided detection areas 41 and 42), that is, the first and second The subtotal signals SPP1 _SUM · SPP2 _SUM are calculated by the calculation of SPP1 _SUM = E + F and SPP2 _SUM = G + H. Normally, the optical pickup 2 uses the astigmatism method for focus control, so that the track direction of the adjustment medium 50 and the division directions on the light receiving elements of the first and second two-divided detection areas 41 and 42 are as follows. Is a direction rotated by 90 degrees, and is also described as such in FIG.

  FIG. 6 shows the main push-pull signal MPP, the sum signal SPP of the first and second sub push-pull signals SPP1 and SPP2, and a tracking error signal (differential push-pull signal) generated by forming a difference between them. The waveform diagram of DPP is shown.

  The sum signal SPP of the first and second sub-push-pull signals SPP1 and SPP2 has an amplitude of the push-pull signal of about 0 with respect to the main push-pull signal MPP. FIG. 6 illustrates the case where the objective lens 15 is shifted, the adjustment medium 50 is tilted, and the like. Therefore, the main push-pull signal MPP and the sum signal SPP each have an offset (DC component) of Δp. ) Has occurred.

Such an offset is
DPP = MPP-k. (SPP1 + SPP2)
It is possible to cancel by obtaining the differential push-pull signal DPP by performing the above calculation. In the differential push-pull signal DPP, the offset (Δp) such as the shift of the objective lens 15 and the tilt of the adjustment medium 50 is canceled. The coefficient k in the above formula is for correcting the difference in light intensity between the main beam and the first and second sub beams, and the intensity ratio is as follows: main beam: first sub beam: second sub beam. If = a: b: b, the coefficient k = a / (2b).

  A method for adjusting the position of the optical pickup 2 in the apparatus 1 will be described below. First, the adjustment medium 50 used for adjustment will be described with reference to FIG. This adjustment medium 50 is used for mounting the optical pickup 2 on the apparatus 1 at an appropriate position without deviation. The adjustment medium 50 includes a groove part 51 and a land part 52, and an information reproduction signal is recorded on the groove part 51 or the land part 52.

  As shown in FIG. 5, the adjustment medium 50 is preliminarily provided with a recording area 53 where a reproduction signal is recorded and an unrecorded area 54 where no reproduction signal is recorded. The recording area 53 and the unrecorded area 54 are provided periodically, and preferably the area width of the recording area 53 in which the recorded area 53 and the unrecorded area 54 are continuously recorded for one or more rounds. Is W0, and the area width of the unrecorded area 54 that is not continuously recorded for one or more rounds is W1, the area width is set to be W0 = W1. Further, the reflectance of the recording area 53 is lower than the reflectance of the unrecorded area 54.

In the adjustment of the apparatus 1, the optical pickup 2 is focused on the adjustment medium 50, and the first and second divided detection areas 41 and 42 corresponding to the first and second sub beams at that time, respectively. The first and second subtotal signals SPP1 _SUM / SPP _SUM , which are the sum signals of the two, are detected and adjusted using them.

7A, the main spot MB indicated by the solid line in FIG. 5 is formed on the center line L1 of the spindle motor 4, and the adjustment medium 50 in the case where no adjustment error of the optical pickup 2 occurs. The output waveforms of the first and second sub-total signals SPP1 _SUM and SPP2 _SUM obtained from FIG. On the other hand, FIG. 7B shows a case where the main spot MB ′ indicated by the broken line in FIG. 5 is not formed on the center line L1 of the spindle motor 4 and an adjustment error ΔY occurs in the optical pickup 2. The output waveforms of the first and second subtotal signals SPP1 ′ _SUM and SPP2 ′ _SUM obtained from the adjustment medium 50 are shown.

The reason why such a difference in waveform appears when there is an adjustment error ΔY of the optical pickup 2 and when there is no adjustment error ΔY will be described. When the first and second subtotal signals SPP1 _SUM / SPP2 _SUM are detected, the adjustment medium 50 is controlled to rotate by the spindle motor 4 that rotates the adjustment medium 50. Therefore, the adjustment medium 50 moves in the radial direction with respect to the objective lens 15.

  As described above, the adjustment medium 50 moves in the radial direction of the adjustment medium 50 with respect to the objective lens 15, whereby the main spot MB, the first and second sub-spots SB1 and SB2 (or the main spot MB ′). The first and second sub-spots SB1 ′ and SB2 ′) cross the recording area 53 and the unrecorded area 54 in the radial direction of the adjustment medium 50.

  When the first and second sub-spots SB1 and SB2 (or the first and second sub-spots SB1 ′ and SB2 ′) cross the recording area 53, the reflectance of the recording area 53 is the unrecorded area 54. Therefore, the output obtained from the first and second divided detection areas 41 and 42 becomes smaller (although not shown, the output obtained from the four divided detection area 40 also becomes smaller similarly). .)

When the main spot MB is disposed on the center line L1 of the spindle motor 4, the first and second sub spots SB1 and SB2 cross the boundary when moving from the recording area 53 to the unrecorded area 54. There is no difference in the time required to cross the boundary even when moving from the unrecorded area 54 to the recorded area 53. For this reason, the outputs of the first subtotal signal SPP1 _SUM obtained from the reflected light of the first subbeam and the second subtotal signal SPP2 _SUM obtained from the reflected light of the second subbeam have the same waveform.

On the other hand, when the main spot MB ′ is not arranged on the center line L1 of the spindle motor 4, the first and second sub-spots SB1 ′ and SB2 ′ of the first and second sub-beams are recorded. There is a difference in time crossing the boundary between the area 53 and the unrecorded area 54. Therefore, it becomes possible to time difference in the output of the 'second sub total signal SPP2 obtained from the reflected light of the _SUM and the second sub-beam' _SUM first sub total signal SPP1 obtained from the reflected light of the first sub-beam occurs , the different waveforms from the first sub-total signal SPP1 _'SUM and the second sub-total signal SPP2' _SUM. In FIG. 7 (b), it shows an output waveform when _{the SUM} 'second sub total signal SPP2 respect _SUM' first subtotal signal SPP1 occurs a delay in broken lines.

FIGS. 8A and 8B show Lissajous waveforms obtained from the waveforms shown in FIGS. 7A and 7B. The Lissajous waveform can be observed by using an oscilloscope, first and second sub-total signal _SPP1 SUM · _{SPP2 SUM} (or first and second sub-total signal SPP1 _'SUM · SPP2' _SUM) for 2-channel input . 8A and 8B, the horizontal axis represents the output of the first subtotal signal SPP1 _SUM or the first SPP1 ′ _SUM , and the vertical axis represents the second subtotal signal SPP2 _SUM or the second SPP2 ′. _SUM output is input.

When the optical pickup 2 is on the center line L1 of the spindle motor 4 and no adjustment error ΔY occurs, the first subtotal signal SPP1 _SUM and the second subtotal signal SPP2 _SUM are in phase. Therefore, the Lissajous waveform is a straight waveform as shown in FIG. In contrast, the center line L1 above the optical pickup 2 Gazure of the spindle motor 4, if the adjustment error ΔY has occurred, the first sub-total signal SPP1 _'SUM and the second sub-total signal SPP2' _SUM and Therefore, the Lissajous waveform becomes a loop-like waveform as shown in FIG.

Therefore, when the relative position between the optical pickup 2 and the spindle motor 4 is adjusted, the shape of the Lissajous waveform becomes the shape shown in FIG. 8A while checking the oscilloscope displaying the Lissajous waveform. Then, the screw is rotated in the direction in which the adjusting screw 7 is pushed in or pulled out by the driving unit 10. Then, the adjustment position itself for detecting the first subtotal signal SPP1 _SUM and the second subtotal signal SPP2 _SUM and adjusting the mounting position of the optical pickup 2 may be the inner periphery side or the outer periphery side of the adjustment medium 50. .

As described above, in the optical pickup 2 in which the amplitude of the push-pull signal of the sub beam is approximately 0, the relative position between the optical pickup 2 and the spindle motor 4 can be adjusted without moving the optical pickup 2 from the outer periphery to the inner periphery. The optical pickup 2 and the spindle motor 4 can be used at any radial position, and only the Lissajous waveforms of the first and second subtotal signals SPP1 _SUM and SPP2 _SUM are observed. Since the relative position of the apparatus 1 can be adjusted, the number of adjustment steps is small, and the apparatus 1 can be adjusted easily and accurately.

[Second Embodiment]
Other embodiments of the present invention will be described below with reference to FIGS. 9 (a) and 9 (b). For convenience of explanation, members having the same functions as those used in the above-described embodiment are denoted by the same reference numerals and description thereof is omitted.

In the first embodiment, the waveform of the first subtotal signal SPP1 _SUM obtained from the reflected light of the first subbeam, and the waveform of the second subtotal signal SPP2 _SUM obtained from the reflected light of the second subbeam, And adjusting the mounting position of the optical pickup 2 by using a Lissajous waveform.

In the present embodiment, the main total signal MPP _SUM obtained from the reflected light of the main beam and the first subtotal signal SPP1 _SUM obtained from the reflected light of the first sub beam or the reflected light of the second sub beam are obtained. The mounting position of the optical pickup 2 is adjusted by comparison with the waveform of the second subtotal signal SPP2 _SUM .

  When the spot formation position is on the center line L 1 of the spindle motor 4 as in the main spot MB shown in FIG. 5, the first and second sub-spots SB 1 and SB 2 are moved from the recording area 53 to the unrecorded area 54. There is no difference between the time for crossing the boundary when moving and the time for the main spot MB to cross the same boundary. Similarly, when moving from the unrecorded area 54 to the recording area 53, the boundary crosses the boundary. There is no difference between the time to do.

Therefore, as shown in FIG. 9A, the output waveform of the first subtotal signal SPP1 _SUM obtained from the reflected light of the first subbeam and the output of the main total signal MPP _SUM obtained from the reflected light of the main beam. The waveform is the same waveform. Although not shown, the output waveform of the second subtotal signal SPP2 _SUM obtained from the reflected light of the second subbeam and the output waveform of the main total signal MPP _SUM obtained from the reflected light of the main beam have the same waveform. .

  On the other hand, when the spot forming position is shifted from the center line L1 of the spindle motor 4 as in the main spot MB ′ shown in FIG. 5, the first and second sub-spots SB1 ′ and SB2 ′ are There is a difference between the time for crossing the boundary when moving from the recording area 53 to the unrecorded area 54 and the time for the main spot MB ′ to cross the boundary. Similarly, there is a difference in the time crossing the boundary when moving to.

Therefore, as shown in FIG. 9 (b), the first sub-total signal SPP1 obtained from the reflected light of the first sub-beam 'and the output waveform of the _SUM, main total signal MPP derived from the reflected light of the main beam' _SUM The output waveform is different from the output waveform, and adjustment by waveform comparison is possible. Although not shown, a second second sub-total signal SPP2 _'SUM output waveform obtained from the reflected light of the sub beam, with the output waveform of the main total signal MPP _SUM obtained from the reflected light of the main beam, different It becomes a waveform. The adjustment using the Lissajous waveform is the same as described above, and thus further description thereof is omitted.

[Third Embodiment]
Other embodiments of the present invention will be described below with reference to FIGS. 10 (a) and 10 (b). For convenience of explanation, members having the same functions as those used in the above-described embodiment are denoted by the same reference numerals and description thereof is omitted.

In the above embodiment, the waveform of the first subtotal signal SPP1 _SUM obtained from the reflected light of the first subbeam and the waveform of the second subtotal signal SPP2 _SUM obtained from the reflected light of the second subbeam are obtained. The waveform of the main total signal MPP _SUM obtained from the reflected light of the main beam or the second sub-total obtained from the first sub-total signal SPP1 _SUM obtained from the first sub-beam or the second sub-beam. The mounting position of the optical pickup 2 has been adjusted by comparing the waveform of the signal SPP2 _SUM .

  In the present embodiment, the output waveform of one of the first and second divided detection areas 41 and 42 that receive the reflected light of the first and second sub-beams is compared to compare the output waveforms of the optical pickup 2. Adjust the mounting position.

  As a signal for comparing waveforms, here, a case will be described in which a waveform comparison is performed between the output from the region E in the first two-divided detection region 41 and the output from the region H in the second two-divided detection region 42. However, the present invention is not limited to this, and any combination of the output from the region in the first two-divided detection region 41 and the output from the region in the second two-divided detection region 42 (E, G), (F, Any of G) and (F, H) may be used. This is because the diffraction grating 13 in which the amplitude of the sub push-pull signal is zero is used.

  When the spot forming position is on the center line L1 of the spindle motor 4 as in the first and second sub spots SB1 and SB2 shown in FIG. 5, the first and second sub spots SB1 and SB2 are recorded. When moving from the area 53 to the unrecorded area 54, there is no difference between the times crossing the boundary. Similarly, when moving from the unrecorded area 54 to the recorded area 53, there is a difference between the times crossing the boundary. Is not seen. Therefore, as shown in FIG. 10A, the output waveform of the signal E obtained from the reflected light of the first sub-beam and the output waveform of the signal H obtained from the reflected light of the second sub-beam are the same waveform. .

  On the other hand, when the spot forming position is shifted from the center line L1 of the spindle motor 4 as in the first and second sub-spots SB1 ′ and SB2 ′ shown in FIG. When the sub-spots SB1 ′ and SB2 ′ move from the recording area 53 to the unrecorded area 54, there is a difference in the time crossing the boundary. There is a difference between the times crossing the boundary. Therefore, as shown in FIG. 10B, the output waveform of the signal E obtained from the reflected light of the first sub-beam and the output waveform of the signal H obtained from the reflected light of the second sub-beam are different from each other. .

  The adjustment using the Lissajous waveform is the same as described above, and thus further description thereof is omitted.

Further, the optical recording medium 16 used in the present embodiment can be similarly adjusted using the configuration of the adjustment medium 50 described above,
In the present embodiment, in addition to the effects of the above-described embodiments, it is not necessary to calculate the first and second subtotal signals obtained from the first and second subspots SB1 and SB2, and the circuit configuration at the time of adjustment Can be simplified.

[Embodiment 4]
Other embodiments of the present invention will be described below with reference to FIGS. 11 (a) and 11 (b). For convenience of explanation, members having the same functions as those used in the above-described embodiment are denoted by the same reference numerals, and description thereof is omitted.

In the present embodiment, the sum signal SPP _SUM of the first subtotal signal SPP1 _SUM obtained from the reflected light of the first subbeam and the subtotal signal SPP2 _SUM obtained from the reflected light of the second subbeam is observed. To adjust the mounting position of the optical pickup 2.

  Here, a section 200 shown in FIGS. 11A and 11B is a section in which the first and second sub-spots SB1 and SB2 cross the recording area 53, and a section 201 is the first sub-spot SB1. And / or a section in which the second sub-spot SB2 crosses the boundary between the recording area and the unrecorded area. In section 202, the first and second sub-spots SB1 and SB2 cross the unrecorded area 54. It shows the section.

  When the spot formation position is on the center line L 1 of the spindle motor 4 as in the main spot MB shown in FIG. 5, the first and second sub-spots SB 1 and SB 2 are moved from the recording area 53 to the unrecorded area 54. There is no difference in the time for crossing the boundary when moving, and there is no difference in the time for crossing the boundary when moving from the unrecorded area 54 to the recorded area 53.

Therefore, as shown in FIG. 11A, the first subtotal signal SPP1 _SUM obtained from the reflected light of the first subbeam and the second subtotal signal SPP2 _SUM obtained from the reflected light of the second subbeam. The output waveform is the same waveform. Therefore, the sum signal SPP _SUM has a waveform that changes sharply when the first and second sub-spots SB1 and SB2 cross the section 201.

On the other hand, when the spot forming position is shifted from the center line L1 of the spindle motor 4 as in the main spot MB ′ shown in FIG. 5, the first and second sub-spots SB1 ′ and SB2 ′ are A difference occurs in the time that crosses the boundary between the recorded area 53 and the unrecorded area 54. Therefore, it becomes possible to time difference in the output of the 'second sub total signal SPP2 obtained from the reflected light of the _SUM and the second sub-beam' _SUM first sub total signal SPP1 obtained from the reflected light of the first sub-beam occurs , the different waveforms from the first sub-total signal SPP1 _'SUM and the second sub-total signal SPP2' _SUM.

Therefore, in the section 201, the difference between the output of the first sub-total signal SPP1 _'SUM and the second sub-total signal SPP2' _SUM results. For this reason, the sum signal SPP _SUM ′ has a waveform that changes stepwise when the first and second sub-spots SB1 and SB2 cross the section 201.

Thus, paying attention to the section 201 in which the first sub spot SB1 and / or the second sub spot SB2 crosses the boundary between the unrecorded area 54 and the recorded area 53, the first and second sub beams are focused. as the first and second sub-total signal SPP1 _'sUM · SPP2' _sUM stepped waveform to a sum signal _{SPP sUM} of does not occur, it is sufficient to adjust the position of the optical pickup 2 and the spindle motor 4.

Even in the optical pickup 2 using the diffraction grating 13 in which the amplitudes of the push-pull signals of the first and second sub-beams are almost zero, the optical pickup 2 is moved from the outer periphery when adjusting the optical pickup 2 and the spindle motor 4. The optical pickup 2 is arranged at the boundary between the recording area 53 and the non-recording area 54 of the adjustment medium 50 without moving to the circumference, and the sum signal of the first and second subtotal signals SPP1 _SUM · SPP2 _SUM at the time of adjustment The relative position between the optical pickup 2 and the spindle motor 4 can be adjusted only by observing only the SPP _SUM .

Although the adjustment medium 50 shown in FIG. 5 is used here as well, it is sufficient that there is a boundary between the recording area 53 and the non-recording area 54. There is no need to periodically provide the unrecorded area 54.
[Fifth Embodiment]
Other embodiments of the present invention will be described below with reference to FIGS. 12 (a) and 12 (b). For convenience of explanation, members having the same functions as those used in the above-described embodiment are denoted by the same reference numerals and description thereof is omitted.

  In the present embodiment, unlike the first to fourth embodiments described above, the reflected light of the first and second sub beams is reflected by the first and second sub beams due to the processing error of the groove interval of the diffraction grating 13 and the aperture limitation of the objective lens 15. This is the case where the incident light is not incident on the two-divided detection areas 41 and 42 and the amplitude of the sub push-pull signal does not become zero. For this reason, the first and second sub push-pull signals SPP1 and SPP2 are offset by the loss of the light amount of the first and second sub beams.

  Mounting the optical pickup 2 by observing the sum signal SPP of the first sub push-pull signal SPP1 obtained from the reflected light of the first sub beam and the second sub push-pull signal SPP2 obtained from the second sub beam Adjust the position.

  12A and 12B show that the reflected light of the first and second sub-beams from the adjustment medium 50 is not incident on the center of the two-divided detection regions 41 and 42, and the two-divided detection region 41 is applied. Shows the output waveforms of the first sub push-pull signal SPP1, the second sub push-pull signal SPP2, and their sum signal SPP when they enter the two-divided detection region 42 downward.

  Here, a section 203 shown in FIGS. 12A and 12B is a section where the first and second sub-spots SB1 and SB2 cross the recording area 53, and a section 204 is the first sub-spot SB1. And / or a section in which the second sub-spot SB2 crosses the boundary between the recording area and the unrecorded area. In a section 205, the first and second sub-spots SB1 and SB2 cross the unrecorded area 54. It shows the section.

  The change in the offset amount between the first sub push-pull signal SPP1 and the second sub push-pull signal SPP2 in the section 200 and the section 203 is caused by the change in the reflectance of the adjustment medium 50.

  When the spot formation position is on the center line L1 of the spindle motor 4 as in the main spot MB shown in FIG. 5, the first and second sub-spots SB1 and SB2 are recorded in the recording area 53 and the unrecorded area 54. There is no difference in the time to cross the border. Therefore, as shown in FIG. 12A, the first sub-push-pull signal SPP1 obtained from the reflected light of the first sub-beam and the second sub-push-pull signal SPP2 obtained from the reflected light of the second sub-beam. There is no time difference in the change in offset generated between the two. As a result, no offset is found in the waveform of the sum signal SPP of the first and second sub push-pull signals SPP1 and SPP2.

  On the other hand, when the spot forming position is shifted from the center line L1 of the spindle motor 4 as in the main spot MB ′ shown in FIG. 5, the first and second sub-spots SB1 ′ and SB2 ′ are A difference occurs in the time that crosses the boundary between the recorded area 53 and the unrecorded area 54. Therefore, there is a time difference in the change in the offset generated between the first sub push-pull signal SPP1 obtained from the reflected light of the first sub beam and the second sub push-pull signal SPP 2 obtained from the reflected light of the second sub beam. . As a result, an offset occurs in the waveform of the sum signal SPP of the first and second sub push-pull signals SPP1 and SPP2.

  This offset gives an offset to the DPP signal which is a tracking error signal, and stable tracking control cannot be obtained near the boundary between the recording area 53 and the unrecorded area 54. For this reason, in the adjustment of the optical pickup 2, it is necessary to remove this offset.

  Therefore, paying attention to the section 204 in which the first sub spot SB1 and / or the second sub spot SB2 crosses the boundary between the unrecorded area 54 and the recorded area 53, the first sub spot SB1 and / or the second sub spot SB2 The positions of the optical pickup 2 and the spindle motor 4 may be adjusted so that no offset occurs in the sum signal SPP of the first and second sub push-pull signals SPP1 and SPP2.

  Thereby, even when the diffraction grating 13 does not have the amplitudes of the push-pull signals of the first and second sub-beams due to, for example, a processing error of the groove interval, the optical pickup 2 is adjusted with the adjustment medium 50 when the optical pickup 2 is adjusted. The optical pickup 2 can be adjusted by observing only the sum signal SPP of the first sub push-pull signal SPP1 and the second sub push-pull signal SPP2 without moving from the outer periphery to the inner periphery (or from the inner periphery to the outer periphery). Therefore, there are few adjustment processes, it can be performed easily and accurately, and stable tracking control is possible.

Although the adjustment medium 50 shown in FIG. 5 is used here as well, it is sufficient that there is a boundary between the recording area 53 and the non-recording area 54. There is no need to periodically provide the unrecorded area 54.
[Sixth Embodiment]
Other embodiments of the present invention will be described below with reference to FIGS. 13 (a) and 13 (b). For convenience of explanation, members having the same functions as those used in the above-described embodiment are denoted by the same reference numerals and description thereof is omitted.

  In the present embodiment, the reflected light of the first and second sub-beams is reflected in the first and second sub-beams due to the processing error of the groove interval of the diffraction grating 13 and the aperture limitation of the objective lens 15 as in the fifth embodiment. This is a case where the center incident light does not enter the two-divided detection areas 41 and 42 and the amplitude of the sub push-pull signal does not become zero.

  In the fifth embodiment, the mounting position of the optical pickup 2 is adjusted by observing the sum signal SPP of the first and second sub push-pull signals SPP1 and SPP2. In this embodiment, the main push is performed. The mounting position of the optical pickup 2 is adjusted by observing a DPP signal that is a difference signal between the pull signal MPP and the SPP signal.

  FIGS. 13A and 13B show that the reflected light of the first and second sub beams from the adjustment medium 50 is not incident on the center of the two-divided detection regions 41 and 42, and the two-divided detection region 41 is reflected. Is an output waveform of the sum signal SPP of the first and second sub push-pull signals SPP1 and SPP2, the main push-pull signal MPP, and the tracking error signal DPP when incident on the two-divided detection region 42 downward. Is shown.

When the spot formation position is on the center line L1 of the spindle motor 4 as in the main spot MB shown in FIG. 5, the first and second sub-spots SB1 and SB2 are recorded in the recording area 53 and the unrecorded area 54. There is no difference in the time to cross the border. Therefore, FIG. 13 (a)
As shown in the waveform SPP, the first sub push-pull signal SPP1 obtained from the reflected light of the first sub beam and the second sub push-pull signal SPP 2 obtained from the reflected light of the second sub beam are generated. As a result of no time difference in offset change, no offset is found in the waveform of the sum signal SPP of the first and second sub-push-pull signals SPP1 and SPP2.

  Therefore, no offset occurs in the waveform of the tracking error signal DPP signal, which is the difference signal between the main push-pull signal MPP and the sub push-pull signal SPP. Therefore, as shown by the waveform DPP in FIG. 13A, the positive side amplitude a and the negative side amplitude b of the tracking error signal DPP signal are a = b with respect to the optimum value N at which no tracking error occurs, and tracking is performed. Control is stable.

  On the other hand, when the spot forming position is shifted from the center line L1 of the spindle motor 4 as in the main spot MB ′ shown in FIG. 5, the first and second sub-spots SB1 ′ and SB2 ′ are A difference occurs in the time that crosses the boundary between the recorded area 53 and the unrecorded area 54.

  Therefore, as shown in the waveform SPP of FIG. 13B, the first sub push-pull signal SPP1 obtained from the reflected light of the first sub beam and the second sub push obtained from the reflected light of the second sub beam. As a result of the time difference in the change in offset generated in the pull signal SPP2, an offset is seen in the waveform of the sum signal SPP of the first and second sub-push pull signals SPP1 and SPP2.

  Therefore, an offset also occurs in the waveform of the tracking error signal DPP signal that is a difference signal between the main push-pull signal MPP and the sub push-pull signal SPP. For this reason, as shown in the waveform DPP of FIG. 13B, the positive side amplitude a and the negative side amplitude b of the tracking error signal DPP signal are a <b with respect to the optimum value N at which no tracking error occurs. Control becomes unstable. In the case where a> b, the tracking control is similarly unstable.

  At this time, the tracking error signal DPP is observed, and when the first sub spot SB1 and / or the second sub spot SB2 crosses the boundary between the unrecorded area 54 and the recorded area 53, a = b The positions of the optical pickup 2 and the spindle motor 4 may be adjusted so that

  Although the adjustment medium 50 shown in FIG. 5 is used here as well, it is sufficient that there is a boundary between the recording area 53 and the non-recording area 54. There is no need to periodically provide the unrecorded area 54.

  Finally, in the first to sixth embodiments described above, the configuration in which the position adjustment is manually performed has been described. However, for example, as illustrated in FIG. According to this, the deviation amount detection unit 9 controls the focus of three beams on an optical recording medium composed of a recording area where a reproduction signal is recorded and an unrecorded area where no reproduction signal is recorded. The amount of deviation between the optical pickup 2 and the center line L1 is detected from the reflected light of at least one of the ± first-order lights, and the adjustment unit 6 is configured to detect the amount of deviation between the optical pickup 2 and the center line L1, and The adjustment screw 7 adjusts the relative position between the optical pickup 2 and the spindle motor 4 based on the detected deviation amount.

  INDUSTRIAL APPLICABILITY The optical pickup adjusting method and the optical pickup adjusting device of the present invention can be used for manufacturing audio, video, and computers that require high-precision mounting of the optical pickup.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates an embodiment of the present invention, and is an explanatory diagram showing a simplified configuration of an optical disc apparatus to which an optical pickup position adjusting method is applied. It is a systematic diagram which shows the optical path of the optical pick-up for reading the signal from an optical recording medium. It is a block diagram of the diffraction grating which makes the amplitude of the sub push pull signal with which the said optical pick-up was provided substantially zero. It is a figure which shows the logic circuit with respect to the output signal from the photodetector provided in the said optical pick-up, and this photodetector. It is explanatory drawing which shows arrangement | positioning of the medium for adjustment, and a beam spot. It is a wave form diagram of a sub push pull signal of a main beam, a sub push pull signal of a sub beam, and a tracking error signal. FIG. 7A is a waveform diagram of two subtotal signals obtained from two subbeams when the position of the main beam is on the center line of the spindle motor, and FIG. 7B is a waveform diagram of the position of the main beam. FIG. 6 is a waveform diagram of two subtotal signals obtained from two subbeams when they are deviated from the center line of the spindle motor. FIG. 8A is a Lissajous waveform diagram in the case where two target signals are in phase, and FIG. 8B is a Lissajous waveform diagram in the case where two target signals are not in phase. FIG. 9A is a waveform diagram of the main total signal obtained from the main beam and the sub total signal obtained from one of the sub beams when the position of the main beam is on the center line of the spindle motor. b) is a waveform diagram of the main total signal obtained from the main beam and the sub total signal obtained from one of the sub beams when the position of the main beam is not on the center line of the spindle motor. FIG. 10A is a waveform diagram of the output signal of one of the sub beams and the output signal of one of the other sub beams when the position of the main beam is on the center line of the spindle motor. FIG. 10B is a waveform diagram of the output signal of one of the sub beams and the output signal of one of the other sub beams when the position of the main beam is not on the center line of the spindle motor. FIG. 11A is a waveform diagram of two subtotal signals obtained from two subbeams when the position of the main beam is on the center line of the spindle motor and a sum signal of the two subtotal signals. FIG. 11B is a waveform diagram of two subtotal signals obtained from two subbeams when the position of the main beam is not on the spindle motor center line, and the sum signal of the two subtotal signals. FIG. 12A is a waveform diagram of the push-pull signals of two sub beams and the sum signal of the push-pull signals when the position of the main beam is on the center line of the spindle motor. These are waveform diagrams of the push-pull signals of two sub beams and the sum signal of these push-pull signals when the position of the main beam is not on the center line of the spindle motor. FIG. 13A is a waveform diagram of the push-pull signal of the main beam, the sum signal of the push-pull signals of the sub beam, and the tracking error signal when the position of the main beam is on the center line of the spindle motor. ) Is a waveform diagram of a main beam push-pull signal, a sub beam push-pull signal sum signal, and a tracking error signal when the position of the main beam is not on the center line of the spindle motor. FIG. 29 is a diagram illustrating another embodiment of the present invention, and is a simplified diagram illustrating a configuration of an optical disc device on which an optical pickup position adjusting device is mounted. It is the bottom view which attached the normal line deviation adjustment apparatus to the conventional optical disk apparatus. FIG. 16A is a waveform diagram of a tracking error signal generated by the optical disc apparatus of FIG. 15, and FIG. 16B is a waveform diagram of a sub signal generated by the optical disc apparatus of FIG. It is a top view of the conventional diffraction grating used when a push pull signal does not generate | occur | produce.

Explanation of symbols

1 Optical disk device (this device)
2 Optical pickup 9 Deviation amount detection unit (deviation amount detection means)
10 Drive unit (adjustment means)
13 Diffraction grating 16 Optical recording medium 19 Optical detector 20 Optical pickup position adjusting device 40 Quadrant detection area (third split detector)
41 1st 2 division | segmentation detection area | region (1st 2 division | segmentation detector)
42 2nd 2 division | segmentation detection area | region (2nd 2 division | segmentation detector)
50 Adjustment medium (optical recording medium)
53 Recording area 54 Unrecorded area

Claims (2)

An optical pickup position adjusting method for adjusting a relative position between the optical pickup and the rotary shaft so that the optical pickup is arranged on a predetermined center line passing through the rotary axis of the optical recording medium,
In the optical pickup, the light emitted from the light source is divided into three beams of zero-order light and ± primary light, and the amplitude of the push-pull signal of the ± primary light obtained from the optical recording medium is almost zero. becomes the diffraction grating being disposed so as to place the same track in the optical recording medium of each spot of the 0 order light and the ± 1-order light,
In the optical recording medium consisting of a recording area where a reproduction signal is recorded and an unrecorded area where no reproduction signal is recorded , the recording area and the unrecorded area are provided periodically and repeatedly,
The three beams are focus-controlled on the optical recording medium, and the reflected light of the + 1st order light obtained at that time is detected by a first two-divided detector substantially divided into two along the track direction. And the sum signal obtained by detecting the reflected light of the −1st-order light with a second two-divided detector substantially divided into two along the track direction. A position adjustment method for an optical pickup, wherein the position of the optical pickup and the rotation shaft are adjusted so that the signals have the same phase . An optical pickup position adjusting device for adjusting a relative position between the optical pickup and the rotating shaft by the position adjusting method according to claim 1.

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