JP2011146110A - Optical disk device, optical pickup, and control method of aberration correction lens - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce vibration time of an aberration correction lens, driven by a stepping motor to drive the aberration correction lens constituting an optical pickup, without complicating the configuration. <P>SOLUTION: An optical disk device includes a light source 21 that emits a light beam having a predetermined wavelength; an aberration correction lens 23 disposed on an optical path with an objective lens which condenses the light beam emitted from the light source 21 on a signal recording plane of an optical disk 2, a stepping motor 32 for step-driving the aberration correction lens 23 to a predetermined position in the optical axis direction, and a controller for controlling the stepping motor 32. The controller generates a voltage for brake on the stepping motor when departing from an ideal stop angle immediately after step-driving. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an optical disc apparatus that has an aberration correction lens and performs recording and / or reproduction of an information signal on an optical disc, an optical pickup, and a method for controlling the aberration correction lens.

  Conventionally, optical discs such as CD (Compact Disc), DVD (Digital Versatile Disc), and BD (Blu-Ray Disc (registered trademark)) have been used as recording media for information signals. There is an optical disk device for performing reproduction. This optical disc apparatus is provided with an optical pickup that moves in the radial direction of the optical disc and irradiates the optical disc with a light beam.

  The optical pickup is generally provided with optical elements such as a light source and an objective lens. In recent years, with the increase in the density of optical discs, etc., aberration management has become important. For example, as a means for correcting spherical aberrations caused by thickness variations in the cover layer of an optical disc, the aberration correction optical lens is moved. The method is adopted. As a drive source for moving the aberration correction lens, a stepping motor having the advantages that the parts cost is relatively inexpensive and that the drive circuit and position control are easy to handle is often used.

  However, since the motor rotating shaft rotates stepwise in the stepping motor, the rotation vibration continues for a while around the target stop angle when the rotation is stopped. For this reason, the aberration correction lens, which is a driven lens, also vibrates with respect to the stop position, which may cause the servo to become unstable and the quality of signal recording / reproduction with respect to the optical disc to deteriorate. Accordingly, in order to stably apply the servo and to stably acquire the signal quality from the optical disc, a waiting time until the vibration of the driven lens stops is required.

  As a technique for suppressing the signal immediately after the driving of the stepping motor is stopped, the following technique can be considered in the case of two-phase excitation. In order to rotate the stepping motor, the voltage between the terminals of the two coils is switched to excite the iron core in the coil, and the angle determined by the motor design for the axis to which the magnet having the predetermined magnetization pattern is bonded is determined for each step. Rotate to. After the driving voltage pattern for generating the driving force of the step immediately before the stop is applied to the coil, the final driving voltage pattern is continuously applied so that the excitation state continues for a certain time in order to suppress the rotational vibration of the motor shaft (hereinafter, "Excitation extension").

  The angle state of the stepping motor shaft in this method is as shown in FIG. After applying the drive voltage, the vibration repeats while attenuating, but by extending the excitation, a force is always generated in the direction of the ideal stop angle on the motor shaft. Accordingly, at time point TA on the time axis in FIG. 7, force is generated in a direction to suppress vibration, but at time point TB on the time axis, force is generated in a direction to accelerate the movement toward the ideal stop angle. However, considering the purpose of shortening the excitation extension time, it is not optimized.

  Further, for example, in the drive system of the optical pickup itself as described in Patent Document 1, there is one in which an applied voltage is changed according to a deviation angle with respect to an ideal stop angle by providing a position sensor or the like. Specifically, in Patent Document 1, a sensor that detects the angle of the motor rotation shaft is mounted, and the applied voltage is changed according to the deviation angle with respect to the ideal stop angle. However, this method requires a sensor for detecting the rotation axis angle, which is disadvantageous in terms of component costs and space efficiency in mechanical design. In addition, an electric circuit configuration is required to realize control of the applied voltage according to the angle of the rotating shaft, which is a disadvantageous factor in that it leads to an increase in the number of parts of the control circuit configuration. On the other hand, the optical pickup is required to be miniaturized, and it is not realistic to provide a detection sensor in a stepping motor for driving an optical element such as an aberration correction lens constituting the optical pickup.

JP 2005-276307 A

  An object of the present invention is to provide an optical disc apparatus, an optical pickup, and an aberration correction lens control method that reduce the vibration time of a lens driven by a stepping motor that drives an aberration correction lens constituting the optical pickup without complicating the configuration. Is to provide.

  In order to achieve this object, an optical disc apparatus according to the present invention includes a light source that emits a light beam having a predetermined wavelength and an objective lens that focuses the light beam emitted from the light source on a signal recording surface of the optical disc. An aberration correction lens provided in the optical path, a stepping motor that step-drives the aberration correction lens to a predetermined position in the optical axis direction, and a control unit that controls the stepping motor. Immediately after that, the brake voltage is generated in the stepping motor when leaving the ideal stop angle.

  An optical pickup according to the present invention is provided in an optical path between a light source that emits a light beam having a predetermined wavelength and an objective lens that focuses the light beam emitted from the light source on a signal recording surface of an optical disc. An aberration correction lens, a stepping motor for driving the aberration correction lens to a predetermined position in the optical axis direction, and a control unit for controlling the stepping motor. The control unit has an ideal stop angle immediately after the step driving. When leaving, the stepping motor generates a braking voltage.

  Further, the aberration correction lens control method according to the present invention includes a light source that emits a light beam having a predetermined wavelength and an objective lens that focuses the light beam emitted from the light source on a signal recording surface of an optical disc. In the aberration correction lens control method for controlling the aberration correction lens provided in the optical path and step-driven to a predetermined position in the optical axis direction by the stepping motor, the stepping motor is provided when the stepping motor leaves the ideal stop angle immediately after the step driving. Generate brake voltage.

  The present invention achieves shortening the vibration time of an aberration correction lens driven by a stepping motor without complicating the configuration. Thus, the present invention realizes that the servo is quickly and stably applied after the operation of the aberration correction lens, shortens the time required to start recording / reproducing with respect to the optical disc, and improves the product performance. .

1 is a diagram showing a schematic configuration of an optical disc apparatus to which the present invention is applied. 1 is a perspective view of an optical disc apparatus to which the present invention is applied. It is a perspective view of the optical pick-up which comprises an optical disk apparatus. It is a perspective view which shows the structure of each optical element which comprises an optical pick-up. It is a perspective view which shows the aberration correction lens which comprises an optical pick-up, and the drive mechanism which drives this aberration correction lens. It is a figure which shows the change of the rotating shaft angle with respect to time immediately after the step drive of a stepping motor with an ideal stop angle. It is a figure for demonstrating basic concepts, such as the control method of the aberration correction lens regarding this invention. It is a figure which shows area T11, T13 spaced apart from an ideal stop angle, area T12 close | similar to an ideal stop angle, and each displacement point TA, TB. It is a figure for demonstrating the excitation extension system which added the excitation control regarding this invention, and the relationship of time, an applied voltage, and a rotation angle is shown with the system without the excitation extension which is a conventional system as a comparative example, and a fixed excitation extension system. FIG. (A) is a figure which shows the change of the rotation angle accompanying the time change in each case. (B) is a figure which shows the change of the applied voltage accompanying the time change in each case.

Hereinafter, the best mode for carrying out the invention will be described in the following order.
1. 1. Configuration of optical disc apparatus 2. Configuration of optical pickup 3. Control method of aberration correction lens Optical pickup and optical disc apparatus to which the present invention is applied

[1. Configuration of optical disk device]
Hereinafter, an optical disk apparatus to which the present invention is applied will be described with reference to the drawings. As shown in FIG. 1, the optical disc apparatus 1 is a recording / reproducing apparatus that records and / or reproduces information signals with respect to the optical disc 2.

  The optical disc 2 that is recorded and / or reproduced by the optical disc apparatus 1 is, for example, a CD (Compact Disc), a CD-R (Recordable), a CD-RW (ReWritable), or the like using a semiconductor laser having an emission wavelength of about 785 nm. It is an optical disk. In an optical disc such as a CD, the thickness of the cover layer that protects the signal recording layer is about 1.1 mm. The optical disk used here is an optical disk such as a DVD (Digital Versatile Disc), DVD-R (Recordable), DVD-RW (ReWritable), DVD + RW (ReWritable) using a semiconductor laser having an emission wavelength of about 655 nm. . An optical disc such as a DVD has a cover layer thickness of about 0.6 mm. An optical disc such as a DVD may be provided with a plurality of recording layers. Furthermore, the optical disk used here is a high-density recording optical disk such as a BD (Blu-ray Disc (registered trademark)) capable of high-density recording using a semiconductor laser having a shorter emission wavelength of about 405 nm (blue-violet). is there. A high-density recording optical disk such as a BD has a cover layer thickness of about 0.1 mm. Optical disks such as BD include an optical disk having a single recording layer (cover layer thickness: 100 μm) and a so-called two-layer optical disk having two recording layers, but also has many recording layers. May be. In the case of a dual-layer optical disc, the cover layer thickness of the recording layer L0 is about 100 μm, and the cover layer thickness of the recording layer L1 is about 75 μm.

  First, the overall configuration of the optical disc apparatus 1 will be described with reference to the overall system diagram of FIG. As shown in FIG. 1, an optical disc apparatus 1 to which the present invention is applied includes an optical pickup 3 that records and reproduces information from an optical disc 2 and a spindle motor 4 that serves as a drive means for rotating the optical disc 2. The optical pickup 3 records data on each track on the optical disk and reproduces data recorded on the optical disk. The optical disc apparatus 1 also includes a feed mechanism 5 that moves the optical pickup 3 in the radial direction of the optical disc 2.

  Specifically, as shown in FIG. 2, the optical disc apparatus 1 has a unit base 6, and has a disc rotation drive mechanism 7 as drive means for driving the unit base 6 to attach and rotate the optical disc 2. The disk rotation drive mechanism 7 is driven by the spindle motor 4 to rotate the optical disk 2.

  Further, the optical disk apparatus 1 is provided with a system controller 8 that controls the spindle motor 4, the feed mechanism 5, and various components. Further, the optical disc apparatus 1 is provided with an A / D converter 9 that converts a signal detected by the optical pickup 3. The system controller 8 controls various components based on signals detected by the optical pickup 3 and converted by the A / D converter 9. The optical pickup 3 is provided with a stepping motor 32 that constitutes a lens driving mechanism for driving the aberration correction lens 23 as will be described later. The optical disc apparatus 1 has a driver IC 10 for driving the stepping motor 32. Is provided. The driver IC 10 is controlled by the system controller 8 and drives the stepping motor 32. Here, the function as a control unit for controlling the stepping motor 32 is provided to the system controller 8 on the optical disc apparatus 1 side, but it may be configured to have a function as a control unit on the optical pickup 3 side. .

  As shown in FIG. 2, the feeding mechanism 5 of the optical pickup 3 is a pair of guide mechanisms that are provided in parallel to each other along the radial direction of the optical disc 2 mounted as a guide mechanism that holds the optical pickup 3 so as to be movable in the radial direction. Guide shafts 11 and 12 are provided. As shown in FIGS. 2 and 3, the pair of guide shafts 11 and 12 are provided on one side and the other side of the tangential direction Tz, which is a direction orthogonal to the radial direction (tracking direction T) of the pickup base 13. The guide parts 14 and 15 are supported. Thus, the guide shafts 11 and 12 support both ends of the optical pickup 3 so as to be linearly movable in the radial direction of the optical disc 2.

  The optical disc apparatus 1 configured as described above rotates the optical disc 2 by the spindle motor 4. Then, the optical disc apparatus 1 drives and controls the feed mechanism 5 in accordance with a control signal from the servo control unit, and moves the optical pickup 3 to a position corresponding to a desired recording track of the optical disc 2, thereby Record and play back information.

  Here, the recording / reproducing optical pickup 3 used in the optical disc apparatus 1 will be described in detail.

[2. Configuration of optical pickup)
Next, the optical pickup 3 to which the present invention is applied, which is used in the optical disk device 1 described above, will be described. The optical pickup 3 described here is an optical pickup having a lens that corrects spherical aberration and the like due to thickness variation of the cover layer by driving in the optical axis direction as a lens for aberration correction, and a stepping motor that drives the lens. It is.

  As shown in FIG. 4, the optical pickup 3 includes a light source 21 such as a laser diode that emits a light beam of a predetermined wavelength, and an objective lens 22 that condenses the light beam emitted from the light source 21 on the signal recording surface of the optical disc. With.

  The light source 21 emits a light beam having a wavelength of about 405 nm corresponding to a high-density optical disc such as a BD. The objective lens 22 has an NA of about 0.85. Here, the light source 21 and the objective lens 22 are configured so as to correspond to an optical disc such as a BD. However, the light source 21 and the objective lens 22 may be adapted to a DVD or a CD, and may correspond to 2 standards or 3 standards. You may comprise so that it may have compatibility. The objective lens 22 is configured to be driven in the tracking direction T, the focus direction F, and the like.

  The optical pickup 3 includes an aberration correction lens 23 that is provided in the optical path between the light source 21 and the objective lens 22 and that can move in the optical axis direction. This is because, as described above, in a high-density optical disc, it is necessary to reduce the diameter of the focused spot on the optical disc, and therefore the NA of the objective lens is increased. That is, in such a high-density optical disk, spherical aberration (hereinafter also referred to as “SA”) generated in the light beam due to the thickness variation of the cover layer of the optical disk affects the data read / write characteristics.

  Specifically, the aberration correction lens 23 includes a pair of concave and convex lenses, that is, includes a fixed lens 23a that is a convex lens and a movable lens 23b that is a concave lens. The aberration correction lens 23 corrects, for example, spherical aberration due to a thickness error of the cover layer by driving the movable lens 23b in the optical axis direction. The aberration correction lens 23 may be composed of only a movable lens.

  The purpose of driving the aberration correction lens 23 is to cancel and correct the spherical aberration caused by the difference in the distance from the optical disk surface to the data surface in the high-density optical disk. In this case, there are two possible causes: one caused by the position of each layer in the multilayer optical disc, and the other caused by variations in the optical disc cover layer thickness and interlayer spacer thickness within one data plane. The aberration correction lens 23 corrects spherical aberration occurring in both of them. The aberration correction lens 23 is driven by a stepping motor 32 and the like which will be described later. The control method of the aberration correction lens] will be described in detail.

  The optical pickup 3 has a half-wave plate (also referred to as “HWP”) 24 and a polarization beam splitter (also referred to as “PBS”) 25 on an optical path between the light source 21 and the aberration correction lens 23. With. Further, the optical pickup 3 includes a rising mirror 26 and a quarter wavelength plate 27 on the optical path between the aberration correction lens 23 and the objective lens 22.

  Further, the optical pickup 3 includes a light amount monitor 28 that receives forward light separated by the polarization beam splitter 25. Further, the optical pickup 3 includes a hologram optical element (also referred to as “HOE”) 29 provided on the optical path of the return light reflected by the optical disc, and a photodetector 30 such as an OEIC that receives the return light. .

  The polarization direction of the light beam emitted from the laser diode as the light source 21 is adjusted by the half-wave plate 24 and is split into two directions by the polarization beam splitter 25. One of the split two light beams is reflected by the reflecting surface of the polarization beam splitter 25 and enters the light amount monitor 28 for adjusting the laser light amount.

  The other one of the split two light beams passes through the reflecting surface of the polarization beam splitter 25, enters the aberration correction lens 23, and is converted into substantially parallel light. The movable lens 23b, which is one of the aberration correction lenses 23, is configured to be linearly movable in the optical axis direction as described above. By combining the lens position and the objective lens 22, a cover of the optical disk is provided. It is possible to cancel out the SA amount caused by the variation in the layer thickness.

  The light beam that has passed through the aberration correction lens 23 is reflected and raised by the rising mirror 26, and is condensed on the signal recording surface of the optical disc 2 by the objective lens 22 through the quarter-wave plate 27.

  The light beam condensed on the signal recording surface of the optical disk 2 is reflected and re-converted into substantially parallel light via the objective lens 22 while including data information, and is converted into linearly polarized light by the quarter wavelength plate 27. Become. Further, this light beam is incident on the polarization beam splitter 25 via the rising mirror 26 and the aberration correction lens 23.

  The light beam incident on the polarization beam splitter 25 is totally reflected by the polarization beam splitter 25, and is split into light including focus (Fcs) error information and tracking (Trk) error information via the hologram optical element 29. , Is incident on the photodetector 30 which is an OEIC.

  The light beam reflected by the optical disc 2 has a position having various information depending on the region in the light beam. The hologram optical element 29 has a function of condensing the light beam in each region at an independent position by combination with a condensing lens. On the light receiving surface of the photodetector 30, a plurality of light receiving patterns are prepared so that the light beam dispersed by the hologram optical element 29 can be received independently, and the voltage is converted from the amount of light received on each light receiving surface. Based on the information, Fcs / Trk error, recording data, and the like are processed.

  Here, a lens position adjusting mechanism (hereinafter also referred to as “SA correction lens driving unit”) 31 for driving the aberration correction lens 23 will be described with reference to FIG.

  The SA correction lens driving unit 31 includes a stepping motor 32, a movable lens holder 33, a guide main shaft 34, a guide sub shaft 35, a lead screw 36, a nut 37, a housing 38, a key groove 39, and a pressurizing spring 40.

  Specifically, the movable lens 23 b of the aberration correction lens 23 is fixed to the movable lens holder 33. The movable lens holder 33 is guided by the guide main shaft 34 and the guide sub shaft 35 so as to have a degree of freedom only in the optical axis direction and to be restrained in other directions.

  A lead screw 36 is press-fitted into the output shaft of the stepping motor 32 serving as a drive source. A nut 37 is fitted to the lead screw 36. The nut 37 is provided with a protruding portion in part, and the protruding portion of the nut 37 is engaged with a key groove 39 provided in the housing 38, so that the rotation is restricted.

  As the stepping motor 32 rotates, the nut 37 can move in the optical axis direction. Further, the movable lens holder 33 is pressed in the optical axis direction by a pressurizing spring 40 that is a compression coil spring, and is pressed against the nut 37. Therefore, when the stepping motor 32 rotates, the movable lens holder 33 pressed against the nut 37 can also move in the optical axis direction.

  The stepping motor 32 is driven by two-phase excitation that is advantageous from the viewpoint of torque. Such stepping motor 32 realizes miniaturization of the motor by using torque as the first priority item for one-phase excitation capable of simplifying an electric circuit and 1-2 phase excitation capable of smooth movement.

  As described above, the SA correction lens driving unit 31 and the aberration correction lens 23 driven by the SA correction lens driving unit 31 have the following first to fifth characteristics. First, in order to perform reproduction (Read) and recording (Write) on the optical disc 2, a light beam emitted from a light source 21 such as a semiconductor laser is converted into parallel light by a fixed lens 23a and a movable lens 23b at a basic position. To do. That is, the fixed lens 23a and the movable lens 23b have a function as a collimator lens.

  Second, when there is variation in the thickness of the cover layer of the optical disc 2, spherical aberration due to this occurs and the recording / reproducing characteristics deteriorate. To improve this, a pair of concave and convex lenses This is solved by the relationship between the combination and the objective lens. In other words, the spherical aberration is canceled by the positional relationship between the aberration correction lens 23 as a pair of concave and convex lenses and the objective lens 22. Such a configuration is also referred to as a “spherical aberration correction mechanism”.

  Third, since the thickness of the cover layer of the optical disc 2 varies depending on the optical disc to be mounted, it has a function of moving the movable lens 23b, which is a concave lens of the spherical aberration correction mechanism, in the optical axis direction. The light beam from the fixed lens 23a is incident on the movable lens 23b, and the position of the movable lens 23b that is a concave lens is moved, whereby convergent light or divergent light is emitted. The light is incident on the objective lens 27, whereby a predetermined spherical aberration is obtained.

  Fourth, regarding the movement of the movable lens 23b, which is a concave lens in the spherical aberration correction mechanism, the rotational force of the stepping motor 32 is caused by the above-described configuration using the lead screw 36 and the nut 37, and the movable lens holder 33 and the movable lens 23b. It is converted to direct power.

  Fifth, the two coils in the stepping motor 32 are given a rectangular wave voltage pattern while being continuously changed, thereby generating a rotational motion. Here, the switching frequency of each voltage pattern is called a drive frequency.

  In the SA correction lens driving unit 31 and the optical disc apparatus 1 including the SA correction lens drive unit 31 as described above, a characteristic method is used that shortens the transient behavior until the movement of the movable lens 23b of the aberration correction lens 23 is completed and complete stop. It has been. That is, if the transient behavior until the complete stop continues for a long time, the light beam may sway, which may affect stable focus (Fcs) and tracking (Trk) servos. The characteristic method described below solves this problem with a simple and inexpensive configuration. Further, the position adjustment of the movable lens 23b of the aberration correction lens 23 described above requires high-speed and high-precision operation, and further miniaturization of the unit itself is important in order to meet the demand for further downsizing of the apparatus in recent years. It becomes an element.

  Specifically, by devising the drive voltage waveform applied to the stepping motor 32, the rotational vibration when the stepping motor is stopped can be reduced in a shorter time without adding components such as a sensor for detecting the rotation angle or increasing the cost. To converge. As a result, it is possible to shorten the waiting time until the aberration correction lens as the driven lens stops. In this regard, the following [3. ] Will be described in detail.

[3. Aberration correction lens control method)
Next, a method for controlling the aberration correction lens in the optical disk device 1 and the optical pickup 3 described above will be described. Prior to the description of the control method, a procedure for driving the aberration correction lens 23 will be described.

  First, when an optical disc is inserted into the optical disc apparatus 1, since the cover layer thickness and interlayer thickness of the optical disc are unknown, an operation for specifying the correction amount of spherical aberration is performed. The optimal aberration correction amount is specified by condensing the light beam on the optical disc and measuring the read characteristic from the return light. As a measurement condition, the stepping motor 23 is driven through the driver IC 10, and the lens position of the movable lens 23b of the aberration correction lens 23 is moved a plurality of times to repeatedly measure. As a result, the system controller 8 specifies the lens position at which a more optimal Read characteristic is obtained, that is, the system controller 8 specifies the spherical aberration correction amount. Then, the system controller 8 drives the stepping motor 32 again through the driver IC 10 and adjusts the lens position, and then starts the actual data recording / reproducing operation.

  Next, a method for controlling the aberration correction lens 23 will be described in detail.

  When the application of the drive voltage pattern immediately before the stop of the stepping motor is stopped under the condition of the drive frequency, as shown in FIG. 6, the motor rotation shaft causes a damped oscillation around the ideal stop angle, and a certain time is required until the motor stops. Necessary. For example, when the driving frequency is 1 kHz, the driving voltage is applied for 1 ms, and then the application is stopped.

  At this time, the frequency of the damped vibration to be generated is a specific frequency determined by the design of each part of the motor. Therefore, by applying a specific voltage pattern, the damped vibration can be quickly converged.

  In FIG. 7, after the drive voltage of the final step is applied, a force acts in the direction of pulling the rotation axis to the ideal stop angle (direction of suppressing the rotation speed) by applying the excitation extension voltage for the time indicated by T11. Therefore, the amplitude is suppressed, which is effective in shortening the convergence time until stopping.

  However, in the section indicated by T12, by applying the excitation extension voltage, a force for accelerating the movement of the rotating shaft in the direction toward the ideal stop angle works, so that the excitation extension voltage is continuously applied until time TB. Thus, the angular velocity of the rotating shaft at the ideal stop angle does not become zero, and the vibration continues and extends the convergence time until the stop.

  Therefore, the optimum value of the excitation extension time in the section of T12 will be considered. When the application of the extended excitation until T11 is stopped at time TA, the angular velocity of the rotating shaft is 0 (stopped) at time TA, and the detent torque generated by the stepping motor itself without being energized. Although rotating in the direction of the ideal stop position, the motor rotation shaft stops near the angle at time TA.

  From the above, by stopping the excitation extension voltage at time TC between time TA and time TB, the motor rotation shaft can be stopped near the ideal stop angle. Depending on the magnitude of the detent torque, the time TC may be earlier than the time TA. Time TA is the point at maximum displacement and zero speed, and time TB is the point at maximum displacement and zero speed.

  Further, since the frequency of the damped vibration is determined by the component configuration and design of the stepping motor, the time TC can be specified. However, there is a possibility that the optimum timing for stopping the excitation extension is shifted due to variations in the frictional force of the sliding portion of the rotating shaft. In order to cope with this case, after the excitation extension is once stopped, the residual from the ideal stop position can be suppressed in a short time by performing the extension extension again for a short time.

  As described above, in the aberration correction lens control method and the optical disc apparatus 1 to which the present invention is applied, the braking voltage is applied to the stepping motor 32 when the system controller 8 as the control unit leaves the ideal stop angle immediately after step driving. It is characterized in that it is generated. This point will be described with reference to FIG. FIG. 8A is a diagram illustrating a change in the rotation angle indicated by the vertical axis in accordance with a change in time t indicated by the horizontal axis. FIG. 8B is a diagram illustrating a change in applied voltage indicated by the vertical axis in accordance with a change in time t indicated by the horizontal axis. In FIGS. 8A and 8B, L1 and LE1 indicated by broken lines indicate that the rotation angle changes as indicated by L1 when an applied voltage as indicated by LE1 is applied. There is a method of waiting for the vibration to be naturally suppressed in the conventional method without so-called excitation extension. In FIGS. 8A and 8B, L2 and LE2 indicated by broken lines are as indicated by L2 when an applied voltage employing a so-called constant excitation extension method as indicated by LE2 is applied. This indicates that there is a change in the rotation angle. Further, in FIGS. 8A and 8B, L3 and LE3 indicated by broken lines are L3 when an applied voltage adopting an excitation extension method with further excitation control as shown by LE3 is applied. This indicates that there is a change in the rotation angle as shown.

  Specifically, for example, TX shown in FIG. 8 indicates one cycle determined by the reciprocal of the frequency of the damped vibration, but at least the first quarter cycle immediately after step driving is in the section of TX1 for braking. It is characterized in that a predetermined applied voltage is applied as a voltage. The frequency of the damped vibration is specified by the weight of the lens to be driven such as the movable lens 23b and the shape of the SA correction lens driving unit 31. In other words, the brake voltage is not applied in the section of TX2 that is the next quarter cycle. Thus, as described above with reference to FIG. 7, the driving force in the braking direction is generated in the T11 section that is going to be away from the ideal stop angle, and the driving force is not generated in the T12 section that is approaching the ideal stop angle. Thus, the vibration time can be further shortened. T11 in FIG. 7 and TX1 in FIG. 8 are corresponding sections. T12 in FIG. 7 and TX2 in FIG. 8 are corresponding sections.

  Further, this control method is characterized in that a predetermined applied voltage is applied as a brake voltage in the TX3 section, which is the next quarter cycle, in addition to the above-described TX1 and TX2 section control. Furthermore, the present invention is characterized in that no brake voltage is applied in the next quarter period TX4. As a result, as described above with reference to FIG. 7, the driving force in the brake direction is generated in the T13 section that is going to be away from the ideal stop angle, and the driving force is generated in the next section that is approaching the ideal stop angle. By not doing so, it is possible to further shorten the vibration time.

  In other words, the first one cycle determined by the reciprocal of the frequency of the damped vibration immediately after step driving is characterized in that four quarter cycles are in the next state. A voltage as a brake voltage is applied to the first and third quarter period sections TX1 and TX3, and a brake voltage is applied to the second and fourth quarter period sections TX2 and TX4. It is characterized in that no voltage is applied as a voltage. In this control method and the like, not only in the first one period, but also in the first two periods or even a plurality of periods, the sections TX1, TX3, TX1 ′, TX3 of the first and third quarter periods. A voltage as a brake voltage may be applied to '. At this time, a voltage as a brake voltage is applied to the second and fourth quarter periods TX2, TX4, TX2 ′, TX4 ′,... You may make it not.

  Furthermore, this control method is characterized in that the voltage to be applied is constant in the section of TX1 or TX3 as described above, that is, a rectangular voltage is applied. . By applying such a pulse-shaped voltage, it is possible to further increase the braking effect against vibration and shorten the vibration time. The same applies when a brake voltage is applied in a plurality of cycles.

  As described above, the aberration correction lens control method to which the present invention is applied has a vibration suppressing effect by the above-described configuration. In other words, the above-described configuration realizes an increase in the vibration suppression effect by driving focusing on the sections TX1, TX2, TX3, TX4... Determined by the reciprocal of the frequency of the damped vibration. This configuration is suitable for driving a stepping motor of an optical component that is required to be manufactured.

[4. Optical pickup and optical disc apparatus to which the present invention is applied]
In the optical pickup 3 and the optical disc apparatus 1 to which the present invention is applied, the movable lens 23b that is a concave lens of the aberration correction lens 23 is moved in the following first and second cases. The first case is a case where initial calibration is performed to confirm the state of the optical disc 2 when the optical disc 2 is inserted into the optical disc apparatus 1. The second case is a case where movement is performed from a layer to which focus servo is applied in a multilayer optical disk to another layer.

  As described above, the optical pickup 3 and the optical disc apparatus 1 to which the present invention is applied are characterized in that the stepping motor 32 generates a braking voltage when the system controller 8 leaves the ideal stop angle immediately after step driving. . Such an optical disc apparatus 1 or the like can shorten the time required to move to the next operation after the movable lens 23b, which is a concave lens, is moved. Particularly in the first case, the movable lens 23b, which is a concave lens, may be moved a plurality of times, and the actual time required for writing and reading after insertion of the optical disc 2 is shortened, thereby reducing the waiting time of the user. It is possible to improve the commercial value.

  In addition, the optical pickup 3 and the optical disc apparatus 1 do not require additional parts or complicated electric circuit configurations to realize this function, which is advantageous in terms of parts and product cost, and is efficient in terms of mechanical space efficiency. Can also contribute to downsizing of set products. In other words, the optical pickup 3 and the optical disc apparatus 1 can realize vibration suppression by controlling based on the sections TX1, TX2, TX3, and TX4, for example, without providing a position sensor or the like, that is, downsizing. This is an advantageous configuration.

  As described above, the optical disc device 1 and the optical pickup 3 to which the present invention is applied can reduce the vibration time of the aberration correction lens driven by the stepping motor without complicating the configuration. Thus, the present invention realizes that the servo is stably applied and improves the quality of recording / reproducing with respect to the optical disc.

  Further, the optical pickup 3 and the optical disc apparatus 1 are described in [3. As described in the above, it is characterized in that a voltage is applied to the predetermined sections TX1, TX3, TX1 ', etc., and no voltage is applied to the predetermined sections TX2, TX4, TX2', etc. Thereby, the effects as described above can be obtained, and the vibration time can be shortened.

  Further, the optical pickup 3 and the optical disc apparatus 1 are characterized in that the voltage to be applied is constant in the section of TX1 and the section of TX3 as described above, that is, a rectangular voltage is applied. Have As a result, it is possible to increase the braking effect against vibration and shorten the vibration time.

  DESCRIPTION OF SYMBOLS 1 Optical disk apparatus, 2 Optical disk, 3 Optical pick-up, 4 Spindle motor, 5 Feeding mechanism, 6 Unit base, 7 Disk rotation drive mechanism, 8 System controller, 9 A / D converter, 10 Driver IC, 11, 12 Guide shaft, 13 Pickup base, 14, 15 Guided part, 21 Light source, 22 Objective lens, 23 Aberration correction lens, 24 1/2 wavelength plate, 25 Polarizing beam splitter, 26 Rising mirror, 27 1/4 wavelength plate, 28 Light intensity monitor , 29 hologram optical element, 30 photodetector, 31 SA correction lens drive unit, 32 stepping motor, 33 movable lens holder, 34 guide main shaft, 35 guide countershaft, 36 lead screw, 37 nut, 38 housing 39 key groove, 40 pressurizing spring

Claims (7)

An aberration correction lens provided in an optical path between a light source that emits a light beam of a predetermined wavelength and an objective lens that focuses the light beam emitted from the light source on a signal recording surface of an optical disc;
A stepping motor that drives the aberration correction lens to a predetermined position in the optical axis direction;
A control unit for controlling the stepping motor,
The control unit is an optical disc apparatus that causes the stepping motor to generate a braking voltage when leaving the ideal stop angle immediately after step driving.   The control unit applies a brake voltage to at least the first quarter cycle section of one cycle determined by the reciprocal of the frequency of the damped vibration immediately after step driving, and applies the brake voltage to the next quarter cycle section. The optical disk apparatus according to claim 1, wherein no voltage is applied.   In the first one cycle determined by the reciprocal of the frequency of the damped vibration immediately after the step drive, the control unit performs braking for the first and third quarter periods of the four quarter periods. 2. The optical disc apparatus according to claim 1, wherein a voltage is applied, and no brake voltage is applied during the second and fourth quarter periods.   In the first plurality of cycles determined by the reciprocal of the frequency of the damped vibration immediately after the step drive, the control unit performs braking for the first and third quarter cycles of the four quarter cycles. 2. The optical disc apparatus according to claim 1, wherein a voltage is applied, and no brake voltage is applied during the second and fourth quarter periods.   5. The optical disc apparatus according to claim 2, wherein the control unit applies a rectangular voltage that is constant in the section as the brake voltage. 6. An aberration correction lens provided in an optical path between a light source that emits a light beam of a predetermined wavelength and an objective lens that focuses the light beam emitted from the light source on a signal recording surface of an optical disc;
A stepping motor that drives the aberration correction lens to a predetermined position in the optical axis direction;
A control unit for controlling the stepping motor,
An optical pickup that causes the stepping motor to generate a braking voltage when the control unit leaves the ideal stop angle immediately after step driving. Provided in the optical path between a light source that emits a light beam of a predetermined wavelength and an objective lens that condenses the light beam emitted from the light source on the signal recording surface of the optical disk, and is predetermined in the optical axis direction by a stepping motor. In the control method of the aberration correction lens for controlling the aberration correction lens step-driven to the position of
A method for controlling an aberration correction lens, wherein a voltage for braking is generated in the stepping motor when leaving the ideal stop angle immediately after step driving.

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