JP2011248979A - Evaluation device of optical pickup device, and evaluation method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an evaluation device of an optical pickup device with which measurement time of an output signal is shortened as much as possible even when a skew value of the optical pickup device or an inclination angle of a lens incorporated in the optical pickup device is comparatively large, and measurement efficiency is improved, and to provide an evaluation method of the same.SOLUTION: The evaluation device 1 of the optical pickup device 20 includes an inclining stage 10 for inclining the optical pickup device 20, a measurement unit 2 for measuring the output signal, and a control unit 3. The control unit 3 makes the optical pickup device 20 inclined in a prescribed measurement range to measure its output signal, and obtains an extreme value in quadric curve approximation of output signals of three points, and sets the extreme value to an appropriate skew value of the optical pickup device 20. If the extreme value is not obtained, the control unit 3 causes additional output signals to be repeatedly measured one point by one point, while increasing the measurement range by a prescribed increment, and obtains an extreme value in quadric curve approximation calculated by adding the additionally measured output signal to the output signals of the three points.

Description

  The present invention relates to an evaluation device related to the performance of an optical pickup device used when reading information from an optical disc or writing information on an optical disc. The present invention also relates to an optical pickup apparatus evaluation method employed in the optical pickup apparatus evaluation apparatus.

  The optical pickup device is used when reading information from an optical disc such as a conventional Blu-ray Disc or DVD (Digital Versatile Disc) or writing information on the optical disc. The optical pickup device irradiates light from a light source toward an optical disc, reads the light reflected by the optical disc, converts it into an electrical signal, and outputs it.

  The optical pickup apparatus evaluation apparatus is an apparatus that evaluates the optical pickup apparatus so that an output signal that the optical pickup apparatus reads from the optical disk and outputs can be obtained with the most appropriate value. In order to obtain an appropriate value of the output signal of the optical pickup device, the optical pickup device evaluation device measures the output signal of the optical pickup device while displacing the optical pickup device itself or a lens built in the optical pickup device. Patent Documents 1 and 2 disclose such an evaluation apparatus and evaluation method for an optical pickup device.

  The optical pickup performance measuring apparatus described in Patent Document 1 calculates a jitter value at a skew position when an optical disk is read by an optical pickup, with respect to a method for measuring optical characteristics of the optical pickup, particularly a method for measuring skew accuracy. The relationship between the skew position and the jitter value is indicated by a quadratic curve, and the optimum skew position of the optical pickup is set at a point where the jitter value of the quadratic curve is minimized. Similarly, in the disk recording and / or reproducing apparatus and the tilt control method thereof described in Patent Document 2, the jitter value is minimized, that is, the best using a second-order approximation for the method of controlling the objective lens to an appropriate tilt angle. The point which becomes becomes.

  The evaluation method of the optical pickup device is indicated by a quadratic curve using, for example, an RF signal that is a signal read from an optical disc, in addition to a method for obtaining a point at which the jitter value indicated by the quadratic curve is minimum. There is also a method for obtaining the point at which the RF signal to be maximized.

JP 2002-208175 A JP 2006-185563 A

  When obtaining an extreme value at which the jitter value and the RF signal are best by quadratic curve approximation, at least three measurement points for the skew value of the optical pickup device itself and the tilt angle of the lens are required. However, as the skew value and the inclination angle increase, it is necessary to widen the measurement range, which increases the number of measurement points and the amount of movement of the measurement stage. As a result, the measurement time is prolonged, and the possibility that the measurement efficiency is lowered is increased.

  The present invention has been made in view of the above points, and in evaluating an optical pickup device so that an output signal that the optical pickup device reads and outputs from an optical disk can be obtained with the most appropriate value, the optical pickup device itself Provided are an optical pickup device evaluation device and an evaluation method thereof that can shorten the measurement time of an output signal as much as possible even when the skew value or the inclination angle of a lens incorporated in the optical pickup device is relatively large, and improve the measurement efficiency. The purpose is to do.

  In order to solve the above-described problems, the present invention provides an optical pickup device evaluation apparatus, wherein the optical pickup device itself or a movable part that tilts a lens built in the optical pickup device, and the optical pickup device reads and outputs from an optical disk. A measurement unit that measures an output signal to be transmitted, and a control unit that controls the operation of the movable unit and the measurement unit, and the control unit controls the movable unit to control the optical pickup device or the lens in a predetermined manner. The measurement unit measures the output signal at three points while inclining within the measurement range, and the extreme value of the output signal is calculated by using a quadratic curve approximation calculated using the output signals at the three points. It is obtained as an appropriate inclination angle of the lens, and on the condition that the extreme value is not obtained, the positive side or the negative side of the movable part While increasing the measurement range by a predetermined increment to either one, the measurement unit repeats the output signal one point at a time, and each time one additional measurement is performed, the additional output signal is output to the three points. The extreme value of the output signal was obtained by quadratic curve approximation calculated in addition to the signal.

  According to this configuration, the extreme value of the output signal, that is, an appropriate inclination angle of the optical pickup device or the lens can be obtained by the measurement of the initial three points at the shortest. Further, even when the extreme value of the output signal cannot be obtained by the three-point measurement, the presence or absence of the extreme value can be determined each time while repeating the additional measurement one by one.

  The “predetermined measurement range” is an arbitrary measurement range of a preset output signal. For example, the angle at which the optical pickup device itself or the lens is tilted using the movable part is 48 minutes, 36 minutes, 0.8 degrees, for example. An angle such as 0.6 degrees may be used. In the embodiment described later, the “predetermined measurement range” is set to “48 minutes (± 24 minutes)”, but is not limited to such a range. Similarly, the “predetermined increment” is an increment of an arbitrary measurement range set in advance, and may be an angle such as 24 minutes, 12 minutes, 0.4 degrees, 0.2 degrees, or the like. In the embodiment described later, “predetermined increment” is set to “(−) 24 minutes”, but it is not limited to such increment.

  Further, in the evaluation apparatus for an optical pickup device having the above-described configuration, the control unit causes the measurement unit to measure the output signals at the three points on the positive side and the negative side in the predetermined measurement range and the central part thereof, and If it is estimated that there is an extreme value on the positive side from the central part on the condition that the extreme value was not obtained, the measurement range is increased on the positive side while the extreme value exists on the negative side from the central part. When estimated, the measurement range was increased to the negative side.

  According to this configuration, even when the extreme value of the output signal cannot be obtained by the initial three-point measurement, the presence / absence of the extreme value can be determined only on either the positive side or the negative side of the measurement range. Thereby, it is possible to greatly reduce the search range of the extreme value of the output signal.

  According to another aspect of the present invention, there is provided an optical pickup device evaluation method comprising: outputting an output signal output from the optical pickup device by reading from the optical disc while tilting the optical pickup device itself or a lens built in the optical pickup device within a predetermined measurement range; A measurement process for measuring three points, a quadratic curve approximation process for calculating a quadratic curve approximation using the output signals of the three points, and an appropriate inclination angle of the optical pickup device or the lens from the quadratic curve An extreme value determination process for determining the presence / absence of an extreme value of the output signal and a measurement in increments of a predetermined increment on either the positive side or the negative side on condition that the extreme value is not obtained in the extreme value determination process The output signal is additionally measured point by point while increasing the range, and the quadratic curve approximation is calculated by adding the additionally measured output signal to the output signal of the three points. Add quadratic curve approximation process that, and the extreme value determination process, was to have, an additional measurement processing repeatedly every time you run one point additional measurements.

  According to this method, the extreme value of the output signal, that is, an appropriate inclination angle of the optical pickup device or the lens can be obtained by measuring the initial three points in the shortest time. Further, even when the extreme value of the output signal cannot be obtained by the three-point measurement, the presence or absence of the extreme value can be determined each time while repeating the additional measurement one by one.

  Further, in the evaluation method of the optical pickup device having the above-described configuration, in the measurement process, the output signals at the three points are measured by the measurement unit at the positive side and the negative side within the predetermined measurement range and at the center thereof, and In the additional measurement process, on the condition that the extreme value was not obtained, when it is estimated that an extreme value exists on the positive side from the central part, the measurement range is increased to the positive side, while on the negative side from the central part When it is estimated that there is an extreme value, the measurement range is increased to the negative side.

  According to this method, even when the extreme value of the output signal cannot be obtained by the initial three-point measurement, the presence / absence of the extreme value can be determined only on either the positive side or the negative side of the measurement range. Thereby, it is possible to greatly reduce the search range of the extreme value of the output signal.

  According to the configuration of the present invention, when evaluating an optical pickup device so that an output signal that the optical pickup device reads and outputs from an optical disk can be obtained with the most appropriate value, the skew value of the optical pickup device itself or the optical pickup device It is possible to provide an evaluation apparatus for an optical pickup device and an evaluation method for the same, in which the measurement time of the output signal is shortened as much as possible even when the appropriate value of the tilt angle of the lens incorporated in the lens is relatively large. it can.

It is a block diagram which shows the evaluation apparatus of the optical pick-up apparatus which concerns on the 1st Embodiment of this invention. It is a perspective view of the inclination stage part of the evaluation apparatus of the optical pick-up apparatus shown in FIG. 2 is a flowchart showing an operation related to calculation of an appropriate value of a skew value of the optical pickup device shown in FIG. It is a 1st example of the graph which shows the relationship between a skew value and RF output signal. It is a 2nd example of the graph which shows the relationship between a skew value and RF output signal. It is a 3rd example of the graph which shows the relationship between a skew value and RF output signal. FIG. 6 is a graph showing the relationship between the skew value and the RF output signal, and shows a state where the measurement range of the second example of FIG. 5 is increased. FIG. 7 is a graph showing the relationship between the skew value and the RF output signal, showing a state where the measurement range of the third example in FIG. 6 is increased. It is a block diagram which shows the evaluation apparatus of the optical pick-up apparatus which concerns on the 2nd Embodiment of this invention. FIG. 10 is a perspective view of an objective lens actuator of the optical pickup device shown in FIG. 9. It is a perspective view of the coil part of the objective lens actuator shown in FIG. It is an example of the graph which shows the relationship between the inclination-angle of an objective lens, and a jitter value.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  First, the structure of the optical pickup apparatus evaluation apparatus according to the first embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a configuration diagram showing an evaluation apparatus for an optical pickup device, and FIG. 2 is a perspective view of an inclined stage portion of the evaluation apparatus for the optical pickup device shown in FIG.

  The optical pickup apparatus evaluation apparatus 1 is an evaluation apparatus related to the performance of the optical pickup apparatus 20 used when reading information from or writing information to the optical disk D, and is movable as shown in FIG. A tilt stage unit 10, a measuring unit 2, a control unit 3, and a memory 4.

  As shown in FIGS. 1 and 2, the tilt stage unit 10 includes a support unit 11, a tangential direction goniometer stage device 12, and a radial direction goniometer stage device 13.

  The support part 11 is disposed on the uppermost part of the inclined stage part 10. The support portion 11 includes two support shafts 11a extending in a substantially horizontal direction. The support shaft 11a has a cantilever shape with one end fixed to the frame 11b. The support portion 11 supports the optical pickup device 20 by inserting the respective support shafts 11a through two through holes 21 provided in the optical pickup device 20 so as to extend in a substantially horizontal direction.

  The optical disk D used for the evaluation of the optical pickup device 20 is transported above the optical pip-up device 20 supported by the support portion 11 as shown in FIG. 1 by a transport mechanism (not shown). The optical pickup device 20 irradiates the optical disc D with light.

  The tangential direction goniometer stage device 12 and the radial direction goniometer stage device 13 are disposed below the support portion 11.

  The tangential direction goniometer stage device 12 is disposed immediately below the support portion 11, supports the support portion 11, and is supported at the bottom by the radial direction goniometer stage device 13. The tangential direction goniometer stage device 12 includes an inclined stage 12a and a drive motor 12b. The tilt stage 12a uses the drive motor 12b to support the support unit 11 and the optical pickup device with the rotation axis extending perpendicularly to the paper surface of FIG. 1, that is, parallel to the direction in which the support shaft 11a of the support unit 11 extends. Twenty rotations (tilts) are possible. The inclination direction of the support portion 11 and the optical pickup device 20 by the tangential direction goniometer stage device 12 is indicated by an arrow “Tan” in FIG.

  On the other hand, the radial direction goniometer stage device 13 is disposed immediately below the tangential direction goniometer stage device 12, supports the tangential direction goniometer stage device 12, and its bottom is fixed to the frame of the evaluation device 1 (not shown). . The radial direction goniometer stage device 13 includes an inclined stage 13a and a drive motor 13b. The tilt stage 13a uses a drive motor 13b to support the support 11 and the optical pickup device 20 horizontally about the rotation axis extending horizontally in the left-right direction in FIG. 1, that is, in the direction perpendicular to the direction in which the support shaft 11a extends. Rotation (tilting) is possible. The inclination direction of the support part 11 and the optical pickup device 20 by the radial direction goniometer stage device 13 is indicated by an arrow “Rad” in FIG.

  The measuring unit 2 measures an output signal output from the optical pickup device 20 read from the optical disk D. This output signal is a signal used for evaluating the performance of the optical pickup device 20, and is an RF output signal that is a signal read from the optical disc D, a jitter value that is a fluctuation range of the output signal, or the like. The measurement unit 2 transmits information related to the output signal obtained from the optical disc D to the control unit 3.

  The control unit 3 is configured by a general microcomputer, and functions as a processor that controls a series of operations related to the operation of the evaluation apparatus 1 based on programs and data stored and input in the microcomputer and the memory 4. is there. That is, the control unit 3 controls the drive motor 12b and the drive motor 13b of the tilt stage unit 10 and control commands related to the operation of the measurement unit 2 to control them.

  Subsequently, an operation related to calculation of an appropriate value of the “skew value” representing the inclination of the optical pip-up device 20 itself, which is one of the evaluation methods using the evaluation device 1 of the optical pickup device 20, is shown in the flow shown in FIG. A description will be given with reference to FIGS. FIG. 3 is a flowchart showing an operation related to calculation of an appropriate value of the skew value of the optical pickup device 20, FIG. 4 is a first example of a graph showing the relationship between the skew value and the RF output signal, and FIG. 5 is a skew value and the RF output signal. 6 is a graph showing the relationship between the skew value and the RF output signal. FIG. 7 is a graph showing the relationship between the skew value and the RF output signal. 8 shows a state in which the measurement range of the second example is increased. FIG. 8 is a graph showing a relationship between the skew value and the RF output signal, and shows a state in which the measurement range of the third example in FIG. 6 is increased. It is shown.

  In this evaluation method of the optical pickup device 20, an appropriate skew value of the optical pickup device 20 is calculated using an RF output signal read from the optical disc D. Therefore, in FIGS. 4 to 8, the horizontal axis represents the skew value (min) of the optical pickup device 20 itself, and the vertical axis represents the RF signal output, and the relationship between the RF output signal and the skew value is approximated by a quadratic curve. And drawing. A square mark indicates the measurement data of the signal by the measuring unit 2, and a circle mark indicates the extreme value of the quadratic curve.

  In addition, although an appropriate skew value calculation of the optical pickup device 20 is executed in each of the tangential direction and the radial direction, the evaluation method is the same in both directions, and therefore the direction will not be particularly limited.

  When the operation of the evaluation apparatus 1 of the optical pickup device 20 is started (start of FIG. 3), the control unit 3 controls the tilt stage unit 10 to keep the optical pickup device 20 within a predetermined measurement range (± W minutes [min]). The RF output signal is measured at three points by the measurement unit 2 while tilting at (step # 101 in FIG. 3). The predetermined measurement range (± W minutes [min]) is set to a measurement range of, for example, ± 24 minutes [min], and is stored in advance in the internal memory or the memory 4 of the control unit 3. The predetermined measurement range can be changed as appropriate. When the measurement range is set to ± 24 minutes, the RF output signal is measured at three points of +24 minutes, −24 minutes, and the center of these.

  When the measurement is finished, the control unit 3 calculates a quadratic curve approximation using the measurement data of the three RF output signals, and calculates the extreme value of the quadratic curve (step # 102). Then, the controller 3 determines whether or not the extreme value of the quadratic curve is within a range of ± (W / 2), that is, within a range of ± 12 minutes (step # 103). In order to improve the measurement accuracy, the presence or absence of an extreme value is determined within a half of the measurement range (± W minutes).

  Here, as a result of the measurement, for example, as shown in the first example of FIG. 4, it is assumed that three RF output signals and an upwardly convex quadratic curve are obtained. In the case of this result, the extreme value is about −4 minutes, and therefore, it exists within a range of ± 12 minutes. When the extreme value exists within a range of ± 12 minutes (Yes in Step # 103), the control unit 3 sets the skew value of the extreme value as the appropriate value (Step # 119), and calculates the appropriate value of the skew value. The operation flow related to is terminated (END in FIG. 3).

  On the other hand, as a result of measurement, for example, as shown in the second example of FIG. 5 or the third example of FIG. 6, when the three points of RF output signals and the quadratic curve are obtained, the extreme value is within the range of ± 12 minutes. It does not exist (No in step # 103). Next, the control unit 3 determines whether or not the extreme value is greater than 0 (step # 104). For example, in the case of the second example shown in FIG. 5, since the extreme value exists between −12 minutes and −24 minutes, the control unit 3 determines that the extreme value is smaller than 0 (No in step # 104). Further, for example, in the case of the third example in FIG. 6, since the extreme value is estimated to be further on the negative side than −24 minutes from the shape of the quadratic curve, the control unit 3 determines that the extreme value is smaller than 0 ( Step # 104 No).

  If it is determined that the extreme value is smaller than 0, the control unit 3 sets the measurement variable n = −2 (step # 105), sets the measurement range to n times W (24 minutes), that is, sets the predetermined increment to −24 minutes− Increase to 48 minutes (step # 106). The formula for obtaining (W × n) for obtaining −24 minutes as the predetermined increment is arbitrarily set in advance and stored in the internal memory or the memory 4 of the control unit 3.

  Then, the control unit 3 determines whether or not the measurement range increased in step # 106 has reached the measurement limit of the evaluation apparatus 1 itself or an arbitrary measurement limit set in advance (step # 107). When it is the measurement limit (Yes in Step # 107), the control unit 3 ends the operation flow related to the calculation of the appropriate value of the skew value without obtaining the appropriate skew value (end of FIG. 3).

  If the measurement range increased in step # 106 is not the measurement limit (No in step # 107), then the control unit 3 sets the increased measurement range to n times W, that is, −48 minutes, to the tilt stage unit 10. And the optical pickup device 20 is tilted to cause the measurement unit 2 to measure the RF output signal (step # 108).

  When the measurement is completed, the control unit 3 calculates a quadratic curve approximation using the measurement data of the four RF output signals, and calculates the extreme value of the quadratic curve (step # 109). Here, for example, in the case of the second example of FIG. 5, when the measurement range is increased to −48 minutes and quadratic curve approximation and extreme value calculation are executed, the result is as shown in FIG. And the control part 3 determines whether the extreme value of a quadratic curve exists in the range from (W / 2) minutes to 0 minute, ie, in the range of -24 minutes-0 minutes (step # 110). . As in step # 103, the presence / absence of an extreme value is determined within a half of the measurement range (W) in order to increase the measurement accuracy.

  For example, in the case of the result as shown in FIG. 7, the extreme value is about −17 minutes, and therefore exists within the range of −24 minutes to 0 minutes. When the extreme value exists within the range of −24 minutes to 0 minutes (Yes in Step # 110), the control unit 3 sets the skew value of the extreme value as the appropriate value (Step # 119), and sets the skew value. The operation flow relating to the calculation of the appropriate value is terminated (END in FIG. 3).

  On the other hand, in the case of the third example of FIG. 6, when the measurement range is increased to −48 minutes and quadratic curve approximation and extreme value calculation are executed, the result is as shown in FIG. As a result, the extreme value does not exist within the range of -24 minutes to 0 minutes (No in Step # 110), so that the control unit 3 sets the measurement variable n to n-1 in preparation for further increasing the measurement range. (Step # 111).

  Subsequently, the control unit 3 repeats the flow from step # 106 to step # 111 until an appropriate skew value of the optical pickup device 20 itself is obtained or the measurement range becomes a limit without obtaining an appropriate skew value. .

  If it is determined in step # 104 that the extreme value is greater than 0 (Yes in step # 104), the flow from step # 112 to step # 118 is performed in the same manner as the flow from step # 105 to step # 111. Detailed description will be omitted. In this case, the control unit 3 causes the measurement unit 2 to repeatedly measure the RF output signal one point at a time while increasing the measurement range by a predetermined increment on the positive side of the tilt stage unit 10, and adds each time additional measurement is performed. The extreme value of the RF output signal is obtained by quadratic curve approximation calculated by adding the measured RF output signal to the initial three RF output signals.

  According to the above embodiment, the extreme value of the RF output signal, that is, an appropriate skew value can be obtained by the measurement of the initial three points at the shortest. Further, even if the extreme value of the RF output signal cannot be obtained by the measurement at these three points, the presence or absence of the extreme value can be determined each time while repeating the additional measurement one by one. Moreover, since the presence or absence of the extreme value of the RF output signal can be determined only on either the positive side or the negative side of the measurement range, the search range for the extreme value of the RF output signal can be greatly reduced. Therefore, the evaluation apparatus 1 and the evaluation method for the optical pickup apparatus 20 in which the measurement time of the RF output signal is shortened as much as possible even when the proper skew value of the optical pickup apparatus 20 itself is relatively large and the measurement efficiency is improved. Can be provided.

  Next, the structure of the optical pickup apparatus evaluation apparatus according to the second embodiment of the present invention will be described with reference to FIGS. 9 is a configuration diagram showing an evaluation apparatus for the optical pickup device, FIG. 10 is a perspective view of an objective lens actuator of the optical pickup device shown in FIG. 9, and FIG. 11 is a perspective view of a coil portion of the objective lens actuator shown in FIG. .

  Here, the evaluation apparatus for an optical pickup device according to the second embodiment evaluates an appropriate inclination angle of an objective lens built in the optical pickup device. 9, the optical pickup device 30 includes a light source 31, a diffraction element 32, a polarizing beam splitter 33, a quarter wavelength plate 34, a collimating lens 35, a rising mirror 36, an objective lens 37, a cylindrical lens 38, And a light detector 39.

  The light source 31 is composed of a semiconductor laser, and emits a 405 nm band laser beam when the optical pickup device 30 is compatible with a Blu-ray disc. The diffraction element 32 is arranged immediately downstream of the light source 31 with respect to the traveling direction of the laser light, and is used to divide the laser light emitted from the light source 31 into main light and two sub-lights according to the necessity for control of the apparatus. .

  The polarizing beam splitter 33 is disposed downstream of the diffraction element 32 and functions as an optical isolator in cooperation with a quarter wavelength plate 34 disposed on the optical disc D side. That is, the polarization beam splitter 33 reflects the laser beam directly emitted from the light source 31 and guides it to the optical disc D side, and transmits the return light reflected by the optical disc D and guides it to the photodetector 39 side.

  The collimating lens 35 is a lens that is disposed on the optical disc D side of the quarter-wave plate 34 and converts incident laser light into parallel light. The collimating lens 35 can be moved in the optical axis direction (left-right direction in FIG. 9) using the collimating lens position adjusting mechanism 40. By moving the collimating lens 35 in the direction of the optical axis, the spherical aberration can be suppressed by adjusting the convergence state or divergence state of the laser light incident on the objective lens 37.

  The raising mirror 36 is disposed on the optical disc D side of the collimating lens 35 and reflects the laser light guided to the collimating lens 35 toward the objective lens 37. Thereby, the traveling direction of the laser light emitted from the light source 31 is changed, and becomes a light traveling in a direction orthogonal to the information recording surface of the optical disc D.

  The objective lens 37 is disposed on the optical disk D side of the rising mirror 36 and close to the optical disk D, and condenses the laser beam guided by the rising mirror 36 on the information recording surface of the optical disk D. The objective lens 37 is parallel to the focus direction (vertical direction in FIG. 9), which is a direction to approach and separate from the optical disk D, using the objective lens actuator 50 which is a movable portion, and the radial direction of the optical disk D. It is possible to move in the track direction (direction perpendicular to the paper surface of FIG. 9). Further, the objective lens actuator 50 can tilt the objective lens 37 about an axis perpendicular to the focus direction and the track direction.

  As shown in FIG. 10, the objective lens actuator 50 includes a lens holder 52 on an act base 51 which is a base member. The lens holder 52 has a rectangular parallelepiped shape, and holds the objective lens 37 on the top thereof. Further, a pair of permanent magnets 53 are provided on the act base 51 so as to face each other with the lens holder 52 sandwiched from the side.

  With respect to the side surface of the lens holder 52 having a rectangular parallelepiped shape, a total of six wires 54 are provided, three on each side, on two side surfaces not sandwiched by the two permanent magnets 53. The three wires 54 on one side of the side surface of the lens holder 52 are arranged in the vertical direction, and one end of each wire 54 is fixed to the side surface of the lens holder 52. The other end of each wire 54 is fixed to a circuit board 55 provided on the act base 51. Accordingly, the lens holder 52 is supported by the wire 54 so as to be swingable.

  Further, a coil portion 56 shown in FIG. 11 is provided inside the lens holder 52. Two coil portions 56 are disposed so as to face the two permanent magnets 53 and the focus coil 56 f disposed so as to surround the optical axis passing through the objective lens 37 along the inner wall of the lens holder 52. A track coil 56t and two tilt coils 56r arranged side by side in a direction perpendicular to the direction in which the pair of permanent magnets 53 face each other are provided below the focus coil 56f. Electric power is supplied to these three coils via a wire 54.

  When a current flows through the focus coil 56f, the lens holder 52 holding the objective lens 37 moves in the focus direction (arrow f in FIG. 10) according to the direction and magnitude of the current due to electromagnetic action with the magnetic field of the permanent magnet 53. To do. Similarly, when a current flows through the track coil 56t, the lens holder 52 holding the objective lens 37 moves in the track direction (arrow t in FIG. 10) according to the direction and magnitude of the current.

  When a current flows through the tilt coil 56r, the lens holder 52 that holds the objective lens 37 rotates around an axis (arrow r in FIG. 10) orthogonal to the focus direction and the track direction according to the direction and magnitude of the current. By this rotation, the objective lens 37 is inclined.

  In FIG. 9, the return light reflected by the information recording surface of the optical disk D passes through the objective lens 37, the rising mirror 36, the collimating lens 35, the quarter wavelength plate 34, and the polarization beam splitter 34 in this order, and the cylindrical lens. 38. The cylindrical lens 38 gives astigmatism to the incident laser beam due to the necessity for controlling the apparatus.

  The laser beam given astigmatism by the cylindrical lens 38 is focused on the light receiving region of the photodetector 39. The photodetector 39 converts the received laser beam into an electrical signal and outputs it.

  On the other hand, the evaluation device 60 of the optical pickup device 30 includes a measurement unit 61, a control unit 62, and a memory 63 as shown in FIG.

  The measuring unit 61 measures an output signal that the optical pickup device 30 reads from the optical disc D and outputs. This output signal is a signal used for evaluating the performance of the optical pickup device 30, and is an RF output signal that is a signal read from the optical disc D, a jitter value that is a fluctuation range of the output signal, or the like. The measurement unit 61 transmits an output signal obtained from the optical disc D to the control unit 62.

  The control unit 62 is configured by a general microcomputer, and functions as a processor that controls a series of operations related to the operation of the evaluation device 60 based on programs and data stored and input in the microcomputer and the memory 63. is there. That is, the control unit 62 transmits control commands related to the operations of the collimating lens position adjusting mechanism 40, the objective lens actuator 50, and the measuring unit 61 of the optical pickup device 30 to control them.

  Next, FIG. 12 is used for the operation related to the calculation of the proper value of the tilt angle of the objective lens 37 built in the optical pip-up device 30, which is one of the evaluation methods using the evaluation device 60 of the optical pickup device 30. I will explain. FIG. 12 is an example of a graph showing the relationship between the tilt angle of the objective lens and the jitter value.

  The operation related to the calculation of the appropriate value of the inclination angle of the objective lens 37 in the second embodiment is basically the same as the operation flow shown in FIG. 3 used in the first embodiment. The detailed description thereof will be omitted, and description will be made with reference to FIG. 3 using the graph of FIG.

  In the evaluation method of the optical pickup device 30, an appropriate inclination angle of the objective lens 37 is calculated using a jitter value of an output signal read from the optical disc D. For this reason, in FIG. 12, the horizontal axis represents the tilt angle (min) of the objective lens 37 and the vertical axis represents the jitter value of the output signal, and the relationship between the tilt angle and the jitter value is plotted as a quadratic curve. A square mark indicates the measurement data of the signal by the measuring unit 61, and a circle mark indicates the extreme value of the quadratic curve.

  When the operation of the evaluation device 60 of the optical pickup device 30 is started (start of FIG. 3), the control unit 62 controls the objective lens actuator 50 to bring the objective lens 37 within a predetermined measurement range (± W minutes [min]). While tilting, the measurement unit 61 measures the jitter value of the output signal at three points (step # 101 in FIG. 3). This predetermined measurement range (± W minutes [min]) is set to a measurement range of, for example, ± 24 minutes [min], and is stored in advance in the internal memory or the memory 63 of the control unit 62. The predetermined measurement range can be changed as appropriate. When the measurement range is set to ± 24 minutes, the jitter value is measured at +24 minutes, −24 minutes, and three points of 0 / minute which is the center thereof.

  When the measurement is finished, the control unit 62 calculates a quadratic curve approximation using the measurement data of the three jitter values, and calculates the extreme value of the quadratic curve (step # 102). Then, the control unit 62 determines whether or not the extreme value of the quadratic curve is within a range of ± (W / 2), that is, within a range of ± 12 minutes (step # 103). In order to improve the measurement accuracy, the presence or absence of an extreme value is determined within a half of the measurement range (± W minutes).

  Here, as a result of the measurement, for example, as shown in FIG. 12, three jitter values and a downwardly convex quadratic curve are obtained. In the case of this result, since the extreme value is about 4 minutes, it exists in the range of ± 12 minutes. When the extreme value exists within a range of ± 12 minutes (Yes in Step # 103), the control unit 62 sets the inclination angle of the extreme value as the appropriate value (Step # 119), and calculates the appropriate value of the inclination angle. The operation flow related to is terminated (END in FIG. 3).

  On the other hand, when the extreme value of the quadratic curve of the jitter value does not exist within the range of ± 12 minutes (No in step # 103), the subsequent steps are the same as those in the first embodiment, so steps # 104 to # 118 are performed. Detailed description is omitted.

  In this way, with respect to the objective lens 37 built in the optical pickup device 30 as well, the extreme value of the jitter value, that is, an appropriate inclination angle can be obtained by measuring the initial three points at the shortest. Furthermore, even if the extreme value of the jitter value cannot be obtained by the measurement at these three points, the presence or absence of the extreme value can be determined each time while repeating the additional measurement one by one. Further, since the presence / absence of the extreme value of the jitter value can be determined only on either the positive side or the negative side of the measurement range, the search range for the extreme value of the jitter value can be greatly reduced. Therefore, even when the proper inclination angle of the objective lens 37 incorporated in the optical pickup device 30 is relatively large, the jitter value measurement time is shortened as much as possible, and the evaluation device 60 of the optical pickup device 30 in which the measurement efficiency is improved. And an evaluation method thereof.

  Although the embodiments of the present invention have been described above, the scope of the present invention is not limited to these embodiments, and various modifications can be made without departing from the spirit of the invention.

  For example, in the embodiment of the present invention, the evaluation of the lens incorporated in the optical pickup device has been described with the objective lens 37 as an example in the second embodiment, but the lens to be evaluated is limited to the objective lens. However, other lenses may be used.

  The present invention can be used in an evaluation apparatus and an evaluation method for an optical pickup device.

DESCRIPTION OF SYMBOLS 1, 60 Evaluation apparatus 2, 61 Measuring part 3, 62 Control part 10 Inclination stage part (movable part)
20 Optical Pickup Device 30 Optical Pickup Device 37 Objective Lens (Lens)
50 Objective lens actuator (movable part)
D Optical disc

Claims (4)

A movable part that tilts the optical pickup device itself or a lens built in the optical pickup device;
A measurement unit that measures an output signal that the optical pickup device reads from the optical disc and outputs;
A control unit for controlling the operation of the movable unit and the measurement unit,
The control unit controls the movable unit to cause the measurement unit to measure the output signal at three points while tilting the optical pickup device or the lens within a predetermined measurement range, and uses the output signals at the three points. The extreme value of the output signal is obtained as an appropriate inclination angle of the optical pickup device or the lens by approximation of the quadratic curve calculated in the above, and the movable part is obtained on condition that the extreme value is not obtained. The output is repeatedly measured each time one additional measurement is performed by causing the measurement unit to repeatedly measure the output signal one point at a time while increasing the measurement range by a predetermined increment to either the positive side or the negative side. An evaluation apparatus for an optical pickup device, wherein an extreme value of the output signal is obtained by quadratic curve approximation calculated by adding a signal to the three output signals.   The control unit causes the measurement unit to measure the output signals of the three points at the positive side and the negative side within the predetermined measurement range and the central part thereof, and on the condition that the extreme value is not obtained, Increase the measurement range on the positive side when an extreme value is estimated to exist on the positive side from the central part, while increasing the measurement range on the negative side when an extreme value is estimated on the negative side from the central part The evaluation apparatus for an optical pickup device according to claim 1. A measurement process for measuring three points of an output signal that the optical pickup device reads and outputs from the optical disc while tilting the optical pickup device itself or a lens built in the optical pickup device within a predetermined measurement range;
A quadratic curve approximation process for calculating a quadratic curve approximation using the output signals of the three points;
As an appropriate inclination angle of the optical pickup device or the lens, an extreme value determination process for determining the presence or absence of an extreme value of the output signal from the quadratic curve;
Additional measurement of the output signal is performed one point at a time while increasing the measurement range by a predetermined increment on either the positive side or the negative side, provided that the extreme value is not obtained in the extreme value determination process. Additional measurement processing that repeats the additional quadratic curve approximation processing for calculating a quadratic curve approximation by adding the measured output signal to the output signals of the three points, and the extreme value determination processing every time one additional measurement is performed. When,
A method for evaluating an optical pickup device, comprising: In the measurement process, the three output signals are measured to the measurement unit at the positive side and the negative side within the predetermined measurement range and at the center thereof,
In the additional measurement process, on the condition that the extreme value is not obtained, when it is estimated that an extreme value exists on the positive side from the central part, the measurement range is increased to the positive side, while on the other hand, it is negative from the central part. 4. The method of evaluating an optical pickup device according to claim 3, wherein when the extreme value is estimated to exist on the side, the measurement range is increased on the negative side.

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