KR20050088783A - Alignment system and method for objective lens of the optical pickup united an actuator - Google Patents

Abstract

Disclosed are an alignment device for aligning an objective lens with an actuator integrated pickup base assembly, and an alignment method using the same.

The alignment device includes an optical pickup holding unit on which the pickup base assembly is mounted, a chuck for fixing the light collecting unit including the objective lens, and an adjusting actuator for adjusting the objective lens in the focusing and / or tracking direction. An objective lens adjusting portion arranged to move to a position to be mounted on the assembly, a spindle motor rotating portion for installing the spindle motor so that the reference disk and the objective lens mounted on the spindle motor face each other as necessary by rotating the spindle motor; And a base structure in which an optical pickup holding unit, an objective lens adjusting unit, and a spindle motor rotating unit are installed.

Description

Alignment system and method for objective lens of the optical pickup united an actuator

The present invention relates to an optical pickup alignment apparatus and method, and more particularly, to an apparatus and method for aligning an objective lens in an optical pickup in which a pickup base and an actuator for supporting an optical system are integrated.

In an optical recording and / or reproducing apparatus for recording arbitrary information on an optical information storage medium or reproducing information recorded on the optical information storage medium by using a condensing spot focusing laser light by an objective lens, the recording capacity is focused. It is determined by the size of the spot. The size S of the condensing spot is determined as shown in Equation 1 by the laser light wavelength? And the numerical aperture NA of the objective lens.

S ∝ λ / NA

Therefore, in order to reduce the size of the light spot formed on the optical information storage medium to increase the density of the optical information storage medium, the optical recording and / or reproducing apparatus has been studied in the direction of adopting a short wavelength light source such as a blue laser and an objective lens having a numerical aperture of 0.6 or more. It is becoming.

Since CDs have been developed to record and / or reproduce information using light of 780 nm wavelength and objective lenses having a numerical aperture of 0.45 or 0.5, many studies have been made to increase information storage capacity by increasing recording density. The result is a DVD in which information is recorded and / or reproduced using light having a wavelength of 650 nm and an objective lens having a numerical aperture of 0.6 or 0.65.

At present, research on a high-density optical information storage medium capable of having a recording capacity of 20 GB or more using light having a blue wavelength, for example, a wavelength of 405 nm has been continuously conducted.

High-density optical information storage media are currently being actively standardized and some standards are nearing completion, using light of blue wavelength, for example, 405 nm wavelength. At this time, the numerical aperture of the objective lens for the high density optical information storage medium is 0.65 or 0.85 as will be described later.

The CD has a thickness of 1.2 mm, but the reason for reducing the thickness to 0.6 mm in the case of DVD is to secure the tolerance due to the tilt of the optical information storage medium because the numerical aperture has increased from 0.45 for the CD to 0.6 for the DVD.

Also, in the case of a high density optical information storage medium having a higher capacity than a DVD, if the numerical aperture of the objective lens for the high density optical information storage medium is increased to, for example, 0.85, the thickness of the high density optical information storage medium should be reduced to about 0.1 mm. do.

In this way, the numerical aperture of the objective lens is increased and the thickness of the optical information storage medium is reduced to be a Blu-ray Disc (hereinafter referred to as BD). In the BD standard, the wavelength of the light source is 405 nm, the numerical aperture of the objective lens is 0.85, and the thickness of the optical information storage medium is approximately 0.1 mm.

High-density optical information storage media currently under development include AOD (Advanced Optical Disc) in addition to BD. This AOD has the same substrate thickness as the DVD, uses the numerical aperture of the same objective lens as the DVD, and only the wavelength of the light source is a blue wavelength, for example, 405 nm, as in the BD standard.

In accordance with the demand for high density and high capacity of the optical information storage medium, in addition to increasing the numerical aperture of the objective lens to reduce the size of the optical spot, there is a demand for thinning and miniaturizing the entire optical system constituting the optical pickup.

In particular, as the demand for the use of optical recording and / or playback equipment in portable terminals such as PDAs, mobile phones, digital cameras, portable disk players, camcorders, and the like, there is an increasing demand for thinner optical pickups. In order to apply to the field of portable terminals, optical pickup has to be thin and small, and to record and / or reproduce information at a high density in order to store and reproduce large amounts of information such as music and video.

However, in the existing bulk optical pickups such as those applied to optical recording and / or reproducing apparatuses for CDs and / or DVDs on the market, the entire optical system is reduced by reducing the size of the optical components constituting the optical pickups. Miniaturization and thinning are already technically reaching their limits.

Therefore, in recent years, research on ultra-small optical pickups that can meet the demand for miniaturization and thinning, can be applied to portable terminals, and can be integrated using semiconductor processing technology is being actively conducted.

Such a miniature optical pickup tends to be integrally formed with an actuator for driving an objective lens and a pickup base for supporting an optical system, while miniaturizing its size.

In general, an ultra-small optical pickup has an optical configuration including a light collecting member including an objective lens, an optical bench provided with a light source and a photo detector, and an optical path forming member coupled thereto, and an actuator is integrally coupled to the optical bench. .

In such a small optical pickup, the optical bench corresponds to a pickup base when compared with a conventional bulk optical pickup. Then, the remaining optical configuration and the actuator except the light collecting member constitute the pickup base assembly.

The objective lens is coupled with the pick-up base assembly, for example, an optical bench, so that its lens center coincides with the optical axis of the light exiting from the light source and must be spaced apart from the optical information storage medium by, for example, an operating distance. Here, when the optical path forming member is positioned on the optical bench and the light collecting member including the objective lens is positioned thereon, the objective lens may be combined with the optical path forming member.

In the case of a micro optical pickup, the objective lens is fixed to the pickup base assembly by adhesion. At this time, in order to fix the objective lens to the pickup base assembly so that the center of the lens is coincident with the optical axis of the light and the distance from the optical information storage medium is the working distance, the objective lens may be adjusted while satisfying the desired conditions while adjusting the objective lens. A device for fixing is required.

However, in the case of existing bulk optical pickups such as those applied to optical recording and / or reproducing apparatus for CDs and / or DVDs currently on the market, the movable part including the objective lens is installed with the remaining optical parts except the objective lens. It is made to be movable with respect to the pickup base. Thus, for example, while bringing the movable part of the actuator on which the objective lens is mounted up-down in the focusing direction, the focus signal is maximized, or the objective lens is placed on the lens holder of the movable part while the tilt and / or skew are adjusted. It is possible to fix it. That is, in the case of the conventional bulk optical pickup, it is possible to determine the proper installation position and angle of the objective lens using the actuator of the optical pickup itself.

However, in the case of an ultra-small optical pickup, since the optical system and the actuator are integrated and only the objective lens can be moved separately, it is impossible to determine the proper installation position and angle of the objective lens using the optical pickup's own actuator as in the conventional bulk optical pickup. Do.

The present invention has been made in view of the above, and an object thereof is to provide an apparatus and method for aligning an objective lens in an optical pickup in which an optical system and an actuator are integrated.

In order to achieve the above object, the present invention provides an alignment device for aligning an objective lens with an actuator integrated pickup base assembly, comprising: an optical pickup holding unit to which the pickup base assembly is mounted; A chuck for fixing the light collecting part including the objective lens and an adjustment actuator for adjusting the objective lens in a focusing and / or tracking direction, the lens being arranged to move the objective lens to a position to be mounted to the pickup base assembly; An objective lens adjusting unit; A spindle motor rotating unit which is installed with a spindle motor, and which rotates the spindle motor so that the reference disk mounted on the spindle motor and the objective lens face each other as necessary; And a base structure in which the optical pickup holding unit, the objective lens adjusting unit, and the spindle motor rotating unit are installed.

The jig unit may further include adjusting a pickup base assembly mounted to the optical pickup holding unit and fixing the pickup base assembly and / or the objective lens in a state where the alignment of the objective lens is completed.

At least one of the optical pickup holding unit, the objective lens adjusting unit, the spindle motor rotating unit, and the jig unit may include a stage assembly capable of adjusting at least one of adjustment, tilt, and skew adjustment in the x, y, and z directions.

The adjusting actuator of the objective adjusting unit may include an adjusting focus actuator configured to perform s-curve searching while moving the objective lens in a focusing direction, and an adjusting tracking actuator configured to adjust the objective lens in a radial direction. .

The present invention is characterized by an actuator-integrated optical pickup in which the objective lens is aligned with the pickup base assembly by the alignment device as described above.

Here, the actuator integrated optical pickup is preferably a microstructure in which a light source and a photodetector are provided on an optical bench.

The objective lens may have a structure having a dummy holder extended to one side thereof in a molding process, or may have a structure coupled to a spacer such that an extension of the dummy holder or the spacer is held in the chuck of the objective lens adjusting unit. After the alignment is completed and the objective lens is bonded to the pickup base assembly, the extension portion of the dummy holder or the spacer may be forcedly cut.

A crack may be formed between the dummy holder and the objective lens or between the spacer and the extended portion to facilitate cutting.

According to an aspect of the present invention, there is provided a method of aligning an objective lens with an actuator integrated pickup base assembly using the alignment device, the method comprising: mounting the pickup base assembly to an optical pickup holding unit; The condenser including the objective lens is fixed to the chuck of the objective lens adjusting unit, the objective lens adjusting unit is moved to a position where the objective lens is to be mounted on the pickup base assembly, and the spindle motor is rotated to mount the spindle motor. Causing the reference disk and the objective lens to face each other; Performs s-curve searching while moving the objective lens up and down in the focusing direction, and adjusts the position along the focusing direction of the objective lens as necessary so that the occurrence points of the s-curve are equally spaced to remove the focus DC offset. Making a step; Finding a reproduction signal maximum point (RF-MAX) while adjusting the skew and / or tilt of the objective lens; Bonding the objective lens to the pickup base assembly while maintaining the state of the objective lens.

Fixing the pickup base assembly and / or the objective lens with a jig after finding the maximum reproduction signal point;

After the alignment of the objective lens is completed, the objective lens is bonded to the pickup base assembly, forcibly cutting the extension of the dummy holder or spacer; may further include a.

Performing the s-curve search and removing the focus DC offset may be performed while the spindle motor is not rotated.

Before the step of finding the maximum point of the reproduction signal, after the correction of the focus DC offset is completed, rotating the spindle motor to generate a reference disk RUN-OUT, and attempting on-axis track (focusing) Wow; The method may further include performing radial tracking.

Hereinafter, an apparatus and method for aligning an objective lens in an actuator integrated optical pickup according to the present invention will be described in detail with reference to the accompanying drawings.

 1 is a perspective view schematically showing the overall structure of an alignment device according to an embodiment of the invention, Figure 2 is an enlarged view of the main part of FIG. 3 illustrates a shape in which the pickup base assembly 90 is held by using the fixing chuck 11 for the jig in the optical pickup holding unit 10 of FIG. 1, and FIG. 4 illustrates the objective lens of the pickup base assembly 90. The structure for mounting 101 is shown.

Referring to the drawings, the alignment device according to the present invention is for aligning the objective lens 101 to the actuator integrated pickup base assembly 90, the base structure, and the optical pickup holding unit is mounted to the pickup base assembly 90 An objective lens adjusting unit 30 having a chuck 31 for fixing the light collecting unit 100 including the objective lens 101 and an adjusting actuator 33, and a spindle motor 51. Spindle motor rotating unit 50 to allow the reference disk 53 and the objective lens 101 mounted on the spindle motor 51 to face each other as necessary, and the optical pickup holding unit 10 and the objective lens adjusting unit 30. And a base structure in which the spindle motor rotating part 50 is installed.

In addition, the alignment apparatus according to the present invention adjusts the pickup base assembly 90 mounted on the optical pickup holding unit 10, and the pickup base assembly 90 is more firmly fixed when the objective lens 101 is aligned. It may further include a jig portion 70 to be fixed.

In addition, the alignment apparatus according to the present invention controls the objective lens adjusting unit 30, and uses the detection signal of the photodetector of the pickup base assembly 90 during the alignment process operation such as s-curve search, which will be described later. A circuit unit (not shown) configured to obtain an on-axis tracking signal (focus error signal), a radial tracking signal (tracking error signal), a reproduction signal, and the like, and to control the objective lens adjustment unit 30 or the like using these signals. It can be provided. Since the structure of such a circuit part can be inferred by the person skilled in the art from the description of the alignment apparatus and alignment process which are mentioned later, the detailed description is abbreviate | omitted.

Meanwhile, the alignment device according to the present invention further includes an imaging device 3, for example, a CCD, so that the alignment device according to the present invention can be easily monitored while aligning and fixing the objective lens 101 at a proper position on the pickup base assembly 90. can do.

The base structure may include a bottom base 1 and a main base 2 positioned on the bottom base 1. The objective lens adjusting unit 30 may be installed at the bottom base 1, and the optical pickup holding unit 10 and the spindle motor rotating unit 50 may be installed at the main base 2. In addition, the photographing apparatus 3 may be installed on the bottom base 1 while being supported by the post 5.

3 and 4, the optical pickup aligned by the alignment device and method according to the present invention is an actuator integrated optical pickup, which includes a light collecting unit 100 including an objective lens 101, and the light collecting unit 100. The optical base and the actuator 91 except for 100 include an integrated pickup base assembly 90.

The optical pickup may be a miniature optical pickup. That is, the optical pickup has an optical configuration including a light collecting part 100 including an objective lens 101, an optical bench provided with a light source and a photo detector, and an optical path forming member coupled thereto, and an actuator on the optical bench. 91 is integrally combined. The optical bench then functions as a pickup base. Therefore, the rest of the configuration except the light collecting portion 100 constitutes the pickup base assembly 90.

Referring to FIG. 4, the light collecting part includes an objective lens 101 and a spacer 103. Here, reference numeral 105 denotes a holder portion 105 which is removed after the objective lens 101 is aligned.

As shown in FIG. 4, the objective lens 101 may have a structure combined with the spacer 103.

5 is a diagram illustrating an example of the spacer 103. As shown in FIG. 5, the extending portion of the spacer 103 may be the holder portion 105.

Alternatively, as shown in FIG. 6, the objective lens 101 may have a structure having a dummy holder 105 ′ extended to one side thereof in a molding process, in which case the dummy holder 105 ′ may be formed. Corresponds to the holder portion 105. In FIG. 6, reference numeral 103 ′ is a spacer, and reference numeral 104 is a bonding point at which UV bonding of the objective lens 101 is performed on the spacer 103 ′ using a UV adhesive. In the case of FIG. 6, in the state where the spacer 103 ′ is fixed to the pickup base assembly 90, the objective lens 101 is bonded to the spacer 103 ′ after the alignment process of the objective lens 101 is performed. can do.

The holder portion 105, that is, the extension portion or the dummy holder of the spacer 103 is held in the chuck 31 of the objective lens adjuster 30.

After the alignment of the objective lens 101 is completed and the objective lens 101 is bonded to the pickup base assembly 90, the holder portion 105, that is, the extension portion or the dummy holder of the spacer 103 is forcibly cut.

Therefore, as shown in FIGS. 5 and 6, a crack 107 is preferably formed between the dummy holder 105 ′ and the objective lens 101 or between the spacer 103 and its extended portion. Do.

7 shows an example of an optical configuration of an ultra-small optical pickup.

Referring to FIG. 7, the microscopic optical pickup includes an optical bench 92, a light source 93 and a photo detector 96 provided on the optical bench 92, an optical path forming member 98, and an objective lens 101. It is configured to include a light collecting unit 100 including.

The pick-up base assembly 90 forms the optical configuration other than the light collecting part 100 and the actuator 91 shown in FIGS. 3 and 4.

The optical bench 92 includes a mounting groove 92 formed therein and a first reflection surface 94 provided on an inclined wall surface of one side of the mounting groove 92. The optical bench 92 is provided with a light source 93 and a photodetector 96, and a monitor photodetector 97.

The light source 93 is installed in the mounting groove 92a of the optical bench 92. The optical path forming member 98 includes an optical path separating surface 98a for converting an advancing path of incident light and a pair of reflecting surfaces 98b and 98c.

The light emitted from the light source 93 is reflected on the first reflecting surface 94 of the optical bench 92, reflected on the optical path separating surface 98a, and then reflected on the reflecting surface 98b to produce an objective lens. Proceed to 101). This light is focused by the objective lens 101 and irradiated to an optical information storage medium (not shown), for example, the reference disk 53. The light reflected from the reference disk 53 passes through the objective lens 101 and is incident on the reflecting surface 98b. After reflecting from the reflecting surface 98b, the light is transmitted through the optical path separation surface 98a to reflect the surface 98c. Incident). This light is reflected by the reflecting surface 98c and received by the photodetector 96 provided in the optical bench 92.

A spacer 95 may be positioned between the optical bench 92 and the light path forming member 98. The inclined surface of the spacer 95 is provided with a reflecting surface 95a for reflecting the light irradiated from the light source to be directed to the monitor photodetector.

Between the optical path forming member 98 and the objective lens 101, a hologram for diffracting the light reflected from the reference disk 53 and guiding its traveling path so that the light travels toward the photodetector 96. The device 99 may be further provided.

In addition, a quarter wave plate (not shown) may be further provided between the optical path forming member 98 and the objective lens 101 to change the polarization of incident light. As such, when the quarter wave plate is provided, the optical path separation surface 98a is preferably a polarization beam separation surface that selectively transmits or reflects the light according to the polarization of the incident light. In this case, the polarization beam splitting surface reflects light of a predetermined polarization irradiated from the light source 93 toward the reference disk 53, is reflected from the reference disk 53, and passes through the quarter-wave plate. The light whose polarization direction is changed is transmitted to be directed to the photodetector 96.

Here, the optical configuration of the optical pickup that can be aligned according to the present invention is not limited to FIG. 7, and may have various optical configurations, except that an actuator is integrally formed in the pickup base assembly.

The pickup base assembly 90 is mounted to the optical pickup holding portion 10. 3 and 4 show a shape in which the pick-up base assembly 90 in which the actuator 91 is integrated is bitten by the chuck 11 of the optical pickup holding unit 10.

As shown in FIGS. 3 and 4, the optical pickup holding portion 10 includes a chuck 11 for mounting and fixing the pickup base assembly 90. The optical pickup holding unit 10 may further include a stage assembly 20. In FIG. 4, reference numeral 95 denotes an area where the objective lens is mounted on the pickup base assembly 90, that is, the holder seating surface.

Referring back to FIGS. 1 and 2, the objective lens adjustment unit 30 may focus on and / or focus the chuck 31 and the objective lens 101 to fix the light collecting unit 100 including the objective lens 101. Or an adjustment actuator 33 for adjusting in the tracking direction. In addition, the objective lens adjuster 30 may further include a stage assembly 40.

The adjustment actuator 33 may perform s-curve searching while moving the objective lens 101 in the focusing direction, and may include an adjustment focus actuator 35 provided to enable axial tracking, that is, focusing. In addition, the adjustment actuator 33 may further include an adjustment tracking actuator 37 provided to adjust the objective lens 101 in the radial direction, that is, radial tracking.

As the adjustment focus actuator 35 and the tracking actuator 37 for adjustment, it is preferable to include a piezo actuator PZT.

The reason why it is preferable to have a piezo actuator as the adjustment focus actuator 35 and the tracking actuator 37 for adjustment is as follows.

The adjustment actuator 33 performs swinging, axial tracking, and radial tracking while the objective lens 101 is fixed. Therefore, the fixing of the objective lens 101 should be made robust to the adjustment actuator 33. Since the attachment of many objective lenses 101 or objective lens holder portions 105 is repeated since it is the actuator 33 for adjustment, there should be no change in the performance of the actuator even in successive repeated attachments. After the objective lens 101 has been adjusted, for example, the holder portion 105 should be separated from the objective lens 101, and the impact at the time of separation should not cause performance degradation and breakage of the actuator.

With the focus actuator 35 for adjustment and the tracking actuator 37 for adjustment, when a piezo actuator is provided, these requirements can be fully satisfied.

The spindle motor rotating part 50 is provided to rotate the spindle motor 51 so that the reference disk 53 and the objective lens 101 mounted on the spindle motor 51 can face each other as necessary. The spindle motor rotation unit 50 may further include a stage assembly 60.

The jig unit 70 has a holder 71 for holding the pickup base assembly 90 or the objective lens 101. In addition, the jig unit 70 may further include a stage assembly 80.

The stage pickups 20, 40, 60, 80 of the optical pickup holding unit 10, the objective lens adjusting unit 30, the spindle motor rotating unit 50, and the jig unit 70 are x, y, and z. At least one of adjustment in the axial direction, tilt and skew adjustment may be provided.

1 and 2 show an example in which the stage assemblies 20, 40, 60, and 80 are arranged to adjust, tilt, and skew in the x, y, and z axis directions, respectively.

That is, as shown in FIG. 1, the stage assembly 40 of the objective lens adjusting unit 30 may include the x-stage 41, the y-stage 43, the z-stage 44, the rotation stage 45, The radial tilt stage 47 and the tangential tilt stage 49 may be configured.

In addition, each stage assembly 20, 60, 80 of the optical pickup holding unit 10, the spindle motor rotating unit 50, and the jig unit 70 may include a stage assembly 40 of the objective lens adjusting unit 30. ) May have substantially the same configuration.

Here, the rotation stage 45, the radial tilt stage 47 and the tangential tilt stage 49 contribute to the tilt and skew adjustment.

 The process of aligning the objective lens 101 to the pickup base assembly 90 by the alignment device having the mechanism structure as described above is as follows.

First, as shown in FIG. 8, in the state where the chuck 31 of the objective lens adjusting unit 30 and the holder 71 of the jig unit 70 are spaced apart from the optical pickup holding unit 10, the optical pickup holding. The pickup base assembly 90 is mounted to the negative fixing chuck 11. In FIG. 8, reference numerals 97 and 99 denote PCB and FPCB, respectively.

Then, as shown in FIG. 9, the jig part 70 is operated to enter the holder 71 close to the pickup base assembly 90, and the light collecting part is placed on the chuck 31 of the objective lens adjusting part 30. Secure (100). When the jig part 70 is not provided here, the operation of operating the jig part 70 to enter the holder 71 close to the pickup base assembly 90 is omitted.

Next, as shown in FIG. 10, the objective lens adjusting unit 30 is operated so that the objective lens 101 mounted on the chuck 31 moves toward the pickup base assembly 90, and thus, on the pickup base assembly 90. The objective lens 101 is moved to the position where the objective lens 101 is to be mounted.

FIG. 11 shows the light collecting unit 100 including the objective lens 101 mounted on the objective lens adjusting unit 30 with the pickup base assembly 90 mounted on the optical pickup holding unit 10. It enters to be positioned on the top, and shows the moment to mount the spindle motor rotating part 50 with the reference disk 53 toward the optical pickup.

Referring to FIG. 11, with the objective lens 101 positioned at an approximate mounting position on the pickup base assembly 90, the spindle motor 51 is rotated so that the reference disk 53 and the objective lens 101 are rotated. Try to face each other.

In this case, the rotation operation of the spindle motor 51 may be performed in a state in which the pickup base assembly 90 is mounted on the optical pickup holding unit 10 and the holder 71 and the light collecting unit 100 do not enter. have.

A reference disk through mounting the pick-up base assembly 90 to the chuck 11 of the optical pickup holding unit 10, adjusting the jig unit 70 for entering the holder 71, rotating the spindle motor 51, or the like ( 53 and the objective lens 101, the adjustment of the objective lens adjustment unit 30 to enter the objective lens 101 is made in conjunction with the adjustment of the stage assembly (20) (40) (60) (80). . At this time, the adjustment can be made while monitoring with the photographing apparatus (3).

As described above, in the state where the reference disk 53 and the objective lens 101 are positioned to face each other, the objective lens is adjusted with the adjusting actuator 33.

In this case, the gap GAP1 between the holder of the initial objective lens 101, that is, the spacer 103 and the holder seating surface 95 may be about a mechanically separable level, for example, about 50 to 100 μm or less. In addition, the gap GAP2 between the upper surface of the objective lens 101 and the reference disk 53 may be set at an operating distance level, for example, about 82 μm.

As described above, with the objective lens 101 positioned at the approximate mounting position on the pick-up base assembly 90, in order to find a position that can accurately maintain the gap GAP2, that is, maintain the working distance, the adjustment focus actuator Using 35, s-curve searching is performed while the objective lens 101 is moved up and down in the focusing direction.

12 shows the s-curve generated by the up-down swing of the objective lens 101. Here, the s-curve as shown in FIG. 12 is irradiated from the light source of the pickup base assembly 90 (eg, the light source 93 of FIG. 7) while the objective lens 101 is up and down, and the reference disk 53 is used. ) Is a signal detected by the photodetector (eg, the photodetector 96 of FIG. 7) of the pickup base assembly 90.

The s-curve is obtained by performing a low frequency swing using the adjusting focus actuator 35.

As can be seen in FIG. 12, when the gap between the objective lens 101 and the reference disk 53, that is, when the gap GAP2 is out of the working distance, a focus DC offset exists so that the s-curve generation interval is It is not equally spaced. In FIG. 12, T is an up and down amplitude of the adjusting focus actuator 35, and may be, for example, about 40 to 60 µm.

Therefore, by using the z-stage 44 of the stage assembly 40 so that the occurrence points of the s-curves are equally spaced, the overall adjustment of the actuator 33 in the z direction can eliminate the focus DC offset.

That is, when there is a focus DC offset, if necessary, the position along the focusing direction of the objective lens 101 is adjusted using the z-stage 44 so that the z-stage when the occurrence points of the s-curves are equally spaced. Stop the movement of (44). This eliminates the DC offset. The gap GAP2 between the objective lens 101 and the reference disk 53 in the state where this DC offset is removed becomes the working distance.

At this time, since the swing, that is, the up and down frequencies on the circuit can be adjusted in the circuit, it is not necessary to rotate the spindle motor 51, whereby the run-out component of the disk is not included.

As described above, when the DC offset is removed while s-curve searching, the s-curve generation points are equally spaced, thereby finding the maximum value of the s-curve, that is, the working distance. This is because the piezo actuator has a moving area of several tens of micrometers, which is only available for AC servo and insufficient for DC servo. This value is the run-out level of the reference disk. Will try.

Here, the closer the gap GAP2 is to the operating distance, the more the DC offset removal process can be minimized.

When the DC offset correction (GAP1, GAP2 maintenance) is completed and the working distance is found, the spindle motor 51 is rotated to rotate the reference disk 53.

By the spindle motor 51 rotation, run-out of the reference disk 53 occurs. At this time, the run-out of the reference disk 53 may occur in a small amount, for example, about 15 to 20 μm. By this run-out of the reference disk 53, an s-curve is generated. The s-curve by this run-out is generated with no DC offset at the current position.

As described above, when the DC offset is removed and the working distance is found, the spindle motor 51 is operated to perform axial tracking, that is, focusing using the s-curve while rotating the reference disk 53. At this time, since the DC offset is removed, only the AC control (AC servo) is performed. At this time, the focusing is followed, for example, at 45 nm.

Next, the radial tracking can be performed by the adjusting tracking actuator 37. Through radial tracking, the light focused by the objective lens 101 can be irradiated to the track center of the reference disk 53. That is, it can be made into the on-tracking state.

When focusing and radial tracking are completed as described above, the skew and tilt of the objective lens are adjusted using the rotation stage 45, the radial tilt stage 47 and the tangential tilt stage 49 of the stage assembly 40. Use the pattern (Eye-Pattern) to find the maximum reproduction point (RF-MAX). Here, the maximum point of the reproduction signal is that the amplitude of the eye pattern of the reproduction signal is maximum.

In this manner, in the state where the maximum reproduction signal point is found, the optical part for adjusting the beam, that is, the pickup base assembly 90 and the objective lens 101, is fixed using the holder 71 of the jig unit 70.

When the process of finding the maximum reproduction signal point is completed as described above, the power supply of the adjustment actuator 33, that is, the adjustment focus actuator 35 and the adjustment tracking actuator 37, is turned off in this state to stop the focusing and tracking operations.

In this case, since all of the DC offsets have been corrected in the above, the movement of the DC component according to the power supply to the adjusting actuator 33, that is, the DC values such as the offset in the axial direction, the radial tilt, and the tangent tilt value are not removed. When the adjustment actuator 33 is powered off, the control is removed.

If the servo performance of the adjustment actuator 33 becomes, for example, 45 nm in the axial direction, for example, 9 nm in the radial direction, only the amount of movement in the focusing and tracking direction (i.e. 45 nm, 9 nm, respectively) even if the servo is stopped It does not affect the optical system adjustment.

In addition, since the tilt, skew, etc. of the objective lens 101 are adjusted by the stage 45, 47, 49, it is irrelevant to the power supply ON-OFF of the adjustment actuator 33. FIG.

As described above, the DC offset is removed and UV bonding is performed while maintaining the current distance between the objective lens 101 and the pickup base assembly 90 while the maximum reproduction signal point is found.

When the fixing is completed by bonding, the alignment process of the objective lens 101 is completed by forcibly cutting the holder portion 105 extending from the objective lens 101, that is, the extension portion or the dummy holder of the spacer. At this time, if a crack is formed between the holder portion 105 and the objective lens 101, the cutting can be easily made. The cutting is performed carefully so that the vibration due to cutting or the amount of impact thereof does not change the position of the objective lens 101.

As described above, the present invention can be used for aligning an objective lens in an actuator integrated optical pickup, in particular, in an optical pickup using an optical bench, and by adjusting a separate external actuator in advance before assembling the optimal position Find it. The optimal position is searched for the s-curve by attempting movement in the focus and track direction to optimize focusing and tracking performance, and by using the generated eye-pattern, the maximum reproduction signal is maximized by maximizing the eye-pattern. Adjust the position of the optical system to reach the point and fix it.

In the present invention, in the series of miniaturization of the optical recording and / or reproducing apparatus, the optical pickup is slimmed and / or miniaturized, and the optical pickup parts equipped with the optical system are miniaturized, and the MEMS (MEMS) is mounted on the actuator driving the objective lens. When mounted through a process such as), it can be used for alignment of the objective lens.

According to the alignment device and method according to the present invention as described above, in the optical pickup in which the actuator is integrated in the pickup base assembly, the objective lens is arranged at a position where the distance from the medium is kept at an operating distance and the reproduction signal is maximized. It is possible.

1 is a perspective view schematically showing the overall structure of an alignment device according to an embodiment of the present invention.

FIG. 2 is an enlarged view of the main part of FIG. 1. FIG.

3 illustrates a shape in which the pickup base assembly is held by using the fixing chuck for the jig of the optical pickup holding part of FIG. 1.

4 shows a structure for mounting an objective lens to a pickup base assembly.

5 is a diagram illustrating an example of a spacer.

6 shows an example in which the objective lens has a dummy holder.

7 shows an example of an optical configuration of an ultra-small optical pickup.

8 shows a state in which the pickup base assembly is mounted on the fixing chuck of the optical pickup holding unit.

9 shows a state in which the jig part is operated to enter the holder in close proximity to the pickup base assembly, and the light collecting part is fixed to the chuck of the objective lens adjusting part.

10 shows a state in which the objective lens is moved to a position to mount the objective lens on the pickup base assembly.

FIG. 11 is a view illustrating an optical pickup holding a pick-up base assembly including an objective lens mounted on an objective lens adjusting unit to be positioned on a pickup base assembly in a state where a pickup base assembly is mounted on an optical pick-up holding unit, and a spindle motor rotating unit equipped with a reference disc; Shows the moment you want to mount.

12 shows the s-curve generated by the up-down swing of the objective lens.

<Description of the symbols for the main parts of the drawings>

1 ... bottom base 2 ... main base

10 ... optical pickup holding unit 11,31 ...

20,40,60,80 .... Stage assembly 30 ... Objective adjuster

33.Adjustable actuator 35 ... Adjustable focus actuator

37 ... Adjustable tracking actuator 50 ... Spindle motor swivel

51 ... spindle motor 53 ... reference disc

70 ... Jig part 71 ... Holder

90 ... pickup base assembly 91 ... actuator

100 ... condenser 101 ... Objective lens

103 ... spacer 105 ... holder part

107 ... cracks

Claims (16)

An alignment device for aligning an objective lens with an actuator integrated pickup base assembly, An optical pickup holding unit to which the pickup base assembly is mounted; A chuck for fixing the light collecting part including the objective lens and an adjustment actuator for adjusting the objective lens in a focusing and / or tracking direction, the lens being arranged to move the objective lens to a position to be mounted to the pickup base assembly; An objective lens adjusting unit; A spindle motor rotating unit which is installed with a spindle motor, and which rotates the spindle motor so that the reference disk mounted on the spindle motor and the objective lens face each other as necessary; And a base structure in which the optical pickup holding unit, the objective lens adjusting unit, and the spindle motor rotating unit are installed. The apparatus of claim 1, further comprising: a jig unit for adjusting the pickup base assembly mounted to the optical pickup holding unit and fixing the objective lens and / or the pickup base assembly in a state where the alignment of the objective lens is completed. Alignment device, characterized in that. The alignment apparatus according to claim 2, wherein the jig unit includes a stage assembly capable of adjusting at least one of adjustment, tilt, and skew adjustment in the x, y, and z directions. The apparatus of claim 1, wherein at least one of the optical pickup holding unit, the objective lens adjusting unit, and the spindle motor rotating unit includes a stage assembly capable of adjusting at least one of adjustment, tilt, and skew adjustment in the x, y, and z directions. Alignment device, characterized in that. According to claim 1, wherein the actuator for adjustment of the objective lens adjustment unit, And an adjusting focus actuator configured to perform s-curve searching while moving the objective lens in a focusing direction. The method of claim 5, wherein the actuator for adjustment, And an adjusting tracking actuator adapted to adjust the objective lens in a radial direction. 7. An actuator integrated optical pickup, characterized in that the objective lens is aligned with the pickup base assembly by the alignment device of any one of claims 1-6. 8. The actuator integrated optical pickup according to claim 7, wherein the optical bench has a micro structure provided with a light source and a photodetector. The method of claim 7, wherein the objective lens has a structure having a dummy holder extended to one side in the molding process, or has a structure coupled to the spacer, the extension portion of the dummy holder or the spacer to the chuck of the objective lens adjustment unit Will be held, And the extension of the dummy holder or the spacer is forcibly cut after the alignment of the objective lens is completed and the objective lens is bonded to the pickup base assembly. 10. The actuator integrated optical pickup of claim 9, wherein a crack is formed between the dummy holder and the objective lens or between the spacer and the extended portion to facilitate cutting. A method of aligning an objective lens with an actuator integrated pickup base assembly using the alignment device according to any one of claims 1 to 6, Mounting the pickup base assembly to the optical pickup holding portion; The condenser including the objective lens is fixed to the chuck of the objective lens adjusting unit, the objective lens adjusting unit is moved to a position where the objective lens is to be mounted on the pickup base assembly, and the spindle motor is rotated to mount the spindle motor. Causing the reference disk and the objective lens to face each other; Performs s-curve searching while moving the objective lens up and down in the focusing direction, and adjusts the position along the focusing direction of the objective lens as necessary so that the occurrence points of the s-curve are equally spaced to remove the focus DC offset. Making a step; Finding a reproduction signal maximum point (RF-MAX) while adjusting the skew and / or tilt of the objective lens; Bonding the objective lens to the pickup base assembly while maintaining the state of the objective lens. 12. The alignment method according to claim 11, further comprising a step of securing a pickup base assembly and / or an objective lens with a jig after finding the maximum reproduction signal point. 12. The method of claim 11, wherein the objective lens has a structure having a dummy holder extended to one side in the molding process, or has a structure coupled to the spacer, the extension portion of the dummy holder or the spacer to the chuck of the objective lens adjustment unit Will be held, And after the alignment of the objective lens is completed and the objective lens is bonded to the pickup base assembly, forcibly cutting the extension of the dummy holder or the spacer. 15. The method of claim 13, wherein a crack is formed between the dummy holder and the objective lens or between the spacer and the extension portion to facilitate cutting. And the crack portion is forcibly cut. 12. The method of claim 11, wherein performing the s-curve search and removing the focus DC offset is performed while the spindle motor is not rotated. 12. The method of claim 11, before the step of finding the maximum reproduction signal point, After the modification of the focus DC offset is completed, rotating a spindle motor to generate a reference disk run-out and attempting an on-axis track (focusing); And performing radial tracking.