JP3865288B2 - Optical head actuator - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical head actuator for recording and reproducing information on a recording medium such as an optical disk such as a compact disk (CD) and a digital versatile disk (DVD) and a magneto-optical disk such as a mini disk (MD). It is.
[0002]
[Prior art]
As an optical head actuator that enables tilt drive, for example, there is a 4-wire support type as shown in FIG. In this case, a so-called moving magnet system is employed, and driving focus coils 71 to 74 and tracking coils 61 and 62 fixed to the fixed member 1 side, and four elastic supports having one end connected to the fixed member 1 side. Focus driving, tracking driving, and tilt driving can be performed by driving permanent magnets 21 to 24 formed on the lens holder 4 suspended and supported on the other end side of the members 31 to 34.
[0003]
That is, permanent magnets 21, 22, 23, 24 for driving formed on the side of the lens holder 4 that is suspended and supported by elastic support members 31 to 34 of a line extending in the X direction in the XYZ rectangular coordinate system, and fixed Each of the coil line segments 71a, 72a, 73a, 74a extending in the Y direction of the focus coils 71, 72, 73, 74 formed on the member 1 side and each of the tracking coils 61, 62 extending in the Z direction. The coil line segments 61a and 62a face each other in the X direction via a gap, and the coil line segments 71a, 72a, 73a, 74a, 61a, and 62a are generated in the X direction by the permanent magnets 21, 22, 23, and 24. It is arranged to be exposed inside. Here, the pair of the focus coils 71 and 73, the pair of the focus coils 72 and 74, and the pair of the tracking coils 61 and 62 are connected in series for each pair, and a desired amount of current is supplied from an independent current source. Supplied.
[0004]
The lens holder 4 holds the objective lens 5 with the optical axis directed in the Z direction, and includes the driving permanent magnets 21, 22, 23, 24 and the energized tracking coil line segments 61a, 62a, 63a, 64a. The objective lens 5 can be moved in the Y direction together with the lens holder 4 by the Lorentz force generated therebetween, and the drive permanent magnets 21, 22, 23, 24 and the energized focus coil line segments 71a, 72a, 73a, Similarly, the objective lens 5 can be moved in the Z direction by the Lorentz force generated between it and 74a.
[0005]
Further, by providing a current difference between the adjacent focus coil line segments 71a-72a and between the focus coil line segments 73a-74a, the objective lens 5 is moved to the X direction using the rotational torque around the X axis generated by the difference in Lorentz force generated. It can be tilted around an axis.
[0006]
In other words, in a rotating disk (not shown) whose recording / reproducing surface is substantially orthogonal to the Z axis and disposed opposite to the objective lens 5, the recording / reproducing surface irradiated with the light beam by deformation such as warpage is parallel to the X axis. The objective lens 5 is also tilted around an axis parallel to the X axis and driven so that the optical axis and the recording / reproducing surface are perpendicular to each other, thereby suppressing the occurrence of aberration of the light beam and detecting it. It is possible to prevent the signal S / N from being lowered.
[0007]
[Problems to be solved by the invention]
However, since the above-described optical head actuator is a moving magnet system in which the driving permanent magnets 21 to 24 are arranged on the lens holder 4 side, the magnetic circuit becomes a remarkably open magnetic path, so that each driving coil is provided. A sufficiently large magnetic flux density cannot be supplied, driving efficiency is low, and the focus coil and tilt driving coil are combined to make the coil configuration complicated.
[0008]
On the other hand, the drive permanent magnets 21 to 24 are disposed on the fixed member 1 side, and a magnetic yoke is formed in the magnetic path portion of the drive permanent magnets 21 to 24 to increase the magnetic efficiency. Then, it is necessary to supply independent currents to the pair of focus coils 71 and 73, the pair of focus coils 72 and 74, and the pair of tracking coils 61 and 62 disposed on the lens holder 4 side. The number of elastic support members that also serve as current supply lines is increased to six to connect the fixing member 1 and the lens holder 4, and the suspension structure becomes complicated.
[0009]
When the lens holder 4 is moved in the Y direction, the lengths of the portions of the coil line segments 71a to 74a of the focus coils 71 to 74 that face the driving permanent magnets 21 to 24 change, respectively. The magnitudes of the Lorentz forces opposite to each other cause a difference between the driving permanent magnets 21 and 22 and between the driving permanent magnets 23 and 24. Since it becomes a driving force, the driving force and the crosstalk as the focus coils 71, 72, 73, 74 are likely to be generated, which affects the focus servo operation.
[0010]
An object of the present invention was made by paying attention to such conventional problems, and it is intended to provide an optical head actuator that has a simple suspension structure and coil configuration, has high drive efficiency of focus and tracking, and can be tilt driven. It is what.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, an optical head actuator according to the present invention extends substantially in the X direction in an XYZ orthogonal coordinate system in which the X direction is a tangential direction, the Y direction is a radial direction, and the Z direction is an optical axis direction. A fixed member that fixes one end of a plurality of elastic support members that suspend and support the lens holder; a movable substrate that is separated from the lens holder and the fixed member and is suspended and supported by at least two elastic support members; A tracking coil for driving the lens holder in the Y direction, a focus coil for driving the lens holder in the Z direction, a permanent magnet for tilt driving for driving the lens holder in the tilt direction, and the tracking coil And a tilt driving coil formed separately from the focus coil, and the fixing member and the coil The tilt driving permanent magnets in one of the dynamic substrate are disposed respectively the tilting driving coils on the other, by the tilt driving permanent magnet pole face is oriented in the X direction magnetic field in the X direction are formed, the The tilt driving coil is disposed opposite to the magnetic pole surface of the tilt driving permanent magnet in the X direction, and the coil line segment of the tilt driving coil faces the X direction that springs from the tilt driving permanent magnet. It is characterized by being exposed to a magnetic field .
[0012]
In a preferred embodiment of the optical head actuator of the present invention, prior to SL at least one of the permanent magnet for the tilt drive the tilting driving coils, among the plurality of elastic support members extending in the schematic X-direction It is arranged near one of the two, and the other is arranged so as to be opposed to the side arranged near the one.
[0013]
In a preferred embodiment of the optical head actuator of the present invention, prior Symbol field in the X direction is formed by the tilt driving permanent magnets, either in the same direction in the Y direction or Z direction the tilting driving coils in pairs And are formed so as to extend adjacent to each other.
[0014]
In a preferred embodiment of the optical head actuator according to the present invention, magnetic fields in the X direction facing each other are formed by the permanent magnets for tilt driving adjacent to each other in pairs in the Y direction or the Z direction, The coils are formed so as to extend in the adjacent direction of the pair of permanent magnets for tilt driving.
[0015]
In a preferred embodiment of the optical head actuator of the present invention includes a fixed member of the elastic supporting member, a supporting portion of the movable substrate of the elastic support member, at least one of between the fixed member and the movable substrate A buffer member is provided at one location.
[0016]
In a preferred embodiment of the optical head actuator of the present invention is to pre-Symbol cushioning member is characterized in that it is formed by gel-like polymer material.
[0017]
In a preferred embodiment of the optical head actuator of the present invention, prior Symbol buffer member is fixed to said fixing member is formed on Kyosuki portion of said coil segment of said tilt driving permanent magnet the tilting driving coil it is characterized in that a conductor that is.
[0018]
In a preferred embodiment of the optical head actuator of the present invention is characterized in that the rear side of the front Symbol tilting driving coils are magnetic yoke provided.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 (a) and 2 (b) are a perspective view and an exploded perspective view showing a first embodiment of the present invention. This optical head actuator is of a four-wire support type moving coil system. A permanent magnet for driving 2 is fixed on the fixed member 1 side, and four elastic support members 31 extending in the X direction from the fixed member 1 side. The lens holder 4 is suspended and supported on the free ends of .about.34, and is movable in the radial direction of the disc (not shown), that is, the Y direction, and the optical axis direction, that is, the Z direction.
[0020]
Further, the lens holder 4 is provided with a light beam parallel to the Z axis irradiated from the objective lens 5 at a position facing the magnetic pole surface of the objective lens 5 and the driving permanent magnet 2, for example, a predetermined track of a disk (not shown). Tracking coil 6 for driving in the Y direction for the purpose of being positioned on the center line of the information pit, and focus coil for driving in the Z direction for the purpose of focusing the light beam on the information pit surface of the disc 7 is formed and held.
[0021]
Here, as shown in FIG. 2A, the coil line segment 6a of the tracking coil 6 that faces the drive permanent magnet 2 in the X direction via a gap extends in the Z direction, and the coil line segment of the focus coil 7 extends. 7a extends in the Y direction.
[0022]
One end 8a of a soft magnetic yoke 8 is connected to the magnetic pole on the back side of the driving permanent magnet 2, and this yoke 8 detours in a substantially U-shape, and the tracking coil 6 and the focus coil 7 are separated by a gap. The other end 8b is disposed so as to be sandwiched therebetween. Therefore, substantially the magnetic flux of the driving permanent magnet 2 is concentratedly supplied to the tracking coil 6 and the focus coil 7, so that the objective lens 4 can be driven efficiently.
[0023]
A movable substrate 9 is connected to the middle position of each of the elastic support members 31 to 34, and as shown in FIG. Magnets 10a and 10b are formed, and the coil segment 11a of the tilt driving coil 11 is opposed to the permanent magnets 10a and 10b for tilt driving in the X direction with a gap and extends in the Y direction. It is formed on the fixing member 1 side. The coil line segment 11a is exposed to a magnetic field directed from the tilt driving permanent magnets 10a and 10b and directed in the opposite X directions. Note that only one of the tilt driving permanent magnets 10a and 10b may be formed, and the tilt driving coil 11 may be formed so as to be biased to a position facing it. The movable substrate 9 may be connected to at least two of the extended elastic support members such as the elastic support members 31 and 32, for example. Further, each of the tilt driving coil 11 and the tilt driving permanent magnets 10a and 10b is disposed at a position rotated 90 degrees around an axis parallel to the X axis, and the tilt driving permanent magnets 10a and 10b are arranged in the Z direction. The coil line segment 11a of the tilt driving coil 11 may be extended in the Z direction.
[0024]
The support portion of the elastic support members 31 to 34 of the fixed member 1 is provided with a pot 12 in which the movable substrate 9 constitutes one side surface thereof, and is filled with a buffer member made of a gel-like polymer, and is movable. The vibration which arose in the board | substrate 9 and the elastic support members 31-34 is suppressed. Furthermore, if necessary, the pot 13 can be provided at the connection portion of the movable substrate 9 with the elastic support members 31 to 34 to fill the buffer member made of the gel-like polymer, whereby the vibration can be more strongly suppressed.
[0025]
Here, when the tracking coil 6 is energized, the Lorentz force acts on the coil segment 6 a of the tracking coil 6 in the Y direction orthogonal to the direction of the current flowing through the coil segment 6 a and the magnetic flux generated by the driving permanent magnet 2. Thus, the lens holder 4 and thus the objective lens 5 are displaced in parallel to the track width direction of the disc (not shown).
[0026]
Similarly, when the focus coil 7 is energized, Lorentz force acts on the coil segment 7a of the focus coil 7 in the Z direction perpendicular to the direction of the current flowing through the coil segment 7a and the magnetic flux generated by the driving permanent magnet 2. Thus, the lens holder 4 and thus the objective lens 5 are displaced parallel to the optical axis direction.
[0027]
When the tilt driving coil 11 is energized, the coil line segment 11a of the tilt driving coil 11 has a direction perpendicular to the direction of the current flowing through the coil line segment 11a and the magnetic flux generated by the tilt driving permanent magnets 10a and 10b. That is, a Lorentz force in the Z direction, which is substantially the same size and opposite to each other, is generated in the portion facing the tilt driving permanent magnet 10a and the portion facing the tilt driving permanent magnet 10b of the coil segment 11a. , Acting as rotational torque around the X axis. Accordingly, the objective lens 5 can be tilted around the X axis together with the lens holder 4 by energizing the tilt driving coil 11 based on the tilt of the disk and the tilt information of the objective lens 5. For example, even if the lens holder 4 is displaced in the Y direction or the Z direction by the tracking coil 6 or the focus coil 7, the relative positional relationship between the coil line segment 11a of the tilt driving coil 11 and the tilt driving permanent magnets 10a and 10b. Therefore, the difference in Lorentz force generated between the portion of the coil line segment 11a facing the tilt driving permanent magnet 10a and the portion facing the tilt driving permanent magnet 10b is small and cancels each other out. As a result, it is difficult to generate a driving force in the Z direction, so that the occurrence of crosstalk with the driving force of the focus coil 7 can be suppressed.
[0028]
FIG. 3 is a perspective view showing a second embodiment of the present invention. This optical head actuator is also of a four-wire support type moving coil system. The permanent magnet for driving 2 is fixed to the fixed member 1 side, and four elastic support members 31 extending in the X direction from the fixed member 1 side. The lens holder 4 is suspended and supported at each intermediate portion of .about.34, and has a structure movable in the radial direction of the disc (not shown), that is, the Y direction, and the optical axis direction, that is, the Z direction.
[0029]
Further, the lens holder 4 is provided with a light beam parallel to the Z axis irradiated from the objective lens 5 at a position facing the magnetic pole surfaces of the objective lens 5 and the driving permanent magnets 25 and 26, for example, on a disk (not shown). A tracking coil 6 for driving in the Y direction for the purpose of being positioned on the center line of a predetermined track information pit, and for driving in the Z direction for the purpose of focusing the light beam on the information pit surface of the disc The focus coil 7 is formed and held.
[0030]
One end 81a, 82a of a soft magnetic yoke 81, 82 is connected to the magnetic pole on the back side of each of the driving permanent magnets 25, 26, and both the yokes 81, 82 have a substantially U-shaped detour and are tracked. The other ends 81b and 82b are disposed so as to sandwich the coil 6 and the focus coil 7 through a gap.
[0031]
Each of the elastic support members 31 to 34 is further extended in the X direction from the suspension support portion of the lens holder 4, and the movable substrate 9 is connected to the tip thereof. A tilt driving permanent magnet 101 is formed on the movable substrate 9, and the tilt driving coils 111 and 112 are opposed to the tilt driving permanent magnet 101 in the X direction and adjacent to the Y direction through a gap. Are arranged around the magnetic yoke 15 around the axis parallel to the Z axis so that the respective coil wire segments 111a and 112a extend in the Y direction, and are formed on the fixing member 1 side. The coil segments 111a and 112a of the respective tilt driving coils 111 and 112 are exposed to an X-direction magnetic field springed out from the tilt driving permanent magnet 101, and the tilt driving permanent magnet 101 is a magnetic yoke. Since the lens holder 4 is driven by the tracking coil 6 or the focus coil 7 and moved, the lens holder 4 is held at a substantially fixed position.
[0032]
Further, a conductor 14 made of copper, aluminum or the like is formed in a gap portion between the tilt driving permanent magnet 101 and the coil line segments 111a and 112a and fixed to the fixing member 1 side. For this reason, when vibration is generated in the elastic support members 31 to 34, the lens holder 4 formed in the intermediate portion thereof, the movable substrate 9 or the like, the change in the magnetic field by the permanent magnet 101 for tilt driving in the conductor 14 is caused. An eddy current flows so as to cancel out the vibration, and the displacement of the tilt driving permanent magnet 101 due to the vibration, and hence the vibration of the lens holder 4 and the objective lens 5 can be suppressed.
[0033]
Here, when the tracking coil 6 is energized, a Lorentz force in the Y direction acts on the coil line segment 6a of the tracking coil 6, and the lens holder 4 and thus the objective lens 5 are made parallel to the track width direction of the disc (not shown). Displace. Similarly, when the focus coil 7 is energized, a Lorentz force in the Z direction acts on the coil line segment 7a of the focus coil 7, and the objective lens 5 is displaced parallel to the optical axis direction.
[0034]
When the coil segments 111a and 112a of the tilt driving coils 111 and 112 are energized so that the current directions are opposite to each other, the coil segments 111a and 112a have a substantially equal size. A Lorentz force in the Z direction facing in the opposite direction is generated and acts as a rotational torque around the X axis. Therefore, the objective lens 5 can be tilted around the X axis together with the lens holder 4 by energizing the tilt driving coils 111 and 112 based on the tilt information of the disk and the tilt information of the objective lens 5. For example, even when the lens holder 4 is displaced in the Y direction or the Z direction by the tracking coil 6 or the focus coil 7, the coil line segments 111a, 112a of the tilt driving coils 111, 112 and the tilt driving permanent magnet 101 are relative to each other. Since the positional relationship does not change greatly, the difference in the magnitude of the Lorentz force in the Z direction opposite to each other generated in the tilt driving permanent magnet 101 is small and it is difficult for the driving force in the Z direction to cancel each other. The occurrence of crosstalk with the driving force of the focus coil 7 can be suppressed.
[0035]
FIG. 4 is a perspective view showing a third embodiment of the present invention. This optical head actuator is of a four-wire support type moving magnet type, and is a lens that holds the objective lens 5 in the middle of each of the four elastic support members 31 to 34 extending in the X direction from the fixed member 1 side. The holder 4 is suspended and supported so as to be movable in the Y direction and the Z direction, respectively.
[0036]
In order to position the light beam parallel to the Z axis irradiated from the objective lens 5 on the fixing member 1 side in the Y direction for the purpose of positioning the light beam on the center line of a predetermined track information pit (not shown), A tracking coil 60 wound around an axis parallel to the Y axis and an axis parallel to the Z axis for driving in the Z direction for the purpose of focusing the light beam on the information pit surface of the disc A wound focus coil 70 is formed, and the driving permanent magnet 20 is opposed to the tracking coil 60 and the focus coil 70 on the lens holder 4 side.
[0037]
The elastic support members 31 to 34 are further extended in the X direction from the suspension support portion of the lens holder 4, and the movable substrate 9 is connected to the tip thereof. A tilt driving permanent magnet 101 is formed on the movable substrate 9, and the tilt driving coils 111 and 112 are opposed to the tilt driving permanent magnet 101 in the X direction and adjacent to the Y direction through a gap. Are arranged around the magnetic yoke 15 around the axis parallel to the Z axis so that the respective coil wire segments 111a and 112a extend in the Y direction, and are formed on the fixing member 1 side. The coil segments 111a and 112a of the respective tilt driving coils 111 and 112 are exposed to an X-direction magnetic field springed out from the tilt driving permanent magnet 101, and the tilt driving permanent magnet 101 is a magnetic yoke. Since the lens holder 4 is driven by the tracking coil 6 or the focus coil 7 and moved, the lens holder 4 is held at a substantially fixed position.
[0038]
In addition, a gap member between the tilt driving permanent magnet 101 and the tilt driving coils 111a and 111b is filled with a buffer member made of a gel polymer, and is generated in the movable substrate 9 and the elastic support members 31 to 34. Vibration can be suppressed.
[0039]
Here, when the tracking coil 60 is energized, the Lorentz force in the Y direction acts on the driving permanent magnet 20, and the objective lens 5 is displaced in parallel to the track width direction of the disk (not shown). When energized, a Lorentz force in the Z direction acts on the driving permanent magnet 20 to displace the objective lens 5 parallel to the optical axis direction.
[0040]
When the coil segments 111a and 112a of the tilt driving coils 111 and 112 are energized so that the current directions are opposite to each other, the coil segments 111a and 112a have a substantially equal size. A Lorentz force in the Z direction facing in the opposite direction is generated and acts as a rotational torque around the X axis. Therefore, the objective lens 5 can be tilted around the X axis together with the lens holder 4 by energizing the tilt driving coils 111 and 112 based on the tilt information of the disk and the tilt information of the objective lens 5. For example, even if the lens holder 4 is displaced in the Y direction or the Z direction by the tracking coil 6 or the focus coil 7, the coil line segments 111a, 112a of the tilt driving coils 111, 112 and the tilt driving permanent magnet 101 are relative to each other. Since the positional relationship does not change greatly, the difference in the magnitude of the Lorentz force in the Z direction opposite to each other generated in the tilt driving permanent magnet 101 is small and it is difficult for the driving force in the Z direction to cancel each other. The occurrence of crosstalk with the driving force of the focus coil 7 can be suppressed.
[0041]
According to this invention, without complicating the suspension structure to allow tilting drive, the tracking coil and the focus coils on the lens holder side, the fixed member side driving permanent magnet with a soft magnetic yoke since it is possible to employ a moving coil system which is arranged, you can configure a good magnetic circuit efficiency can be maintained high drive efficiency can be supplied to the magnetic flux of sufficient magnitude to each coil for driving .
Further, since the tilt driving coil is formed separately from the focus coil, a simple coil configuration can be achieved.
Further, even when the lens holder is moved in the Y direction or the Z direction, the magnitudes of the mutually opposite Lorentz forces generated in the tilt driving coil or the tilt driving permanent magnet can be maintained at the same level and can be canceled out. Therefore, it is difficult for crosstalk with the driving force by the focus coil to occur, and the focus servo operation is hardly affected.
In each of the above-described embodiments, the example in which the tilt driving permanent magnet is formed on the rotating substrate side has been described. However, the tilt driving coil is formed on the movable substrate side and the tilt member is tilted on the fixed member side. Even if the driving permanent magnet is formed, the same effect can be obtained.
[0042]
【The invention's effect】
Since the optical head actuator according to the present invention is configured as described above, a strong magnetic flux is generated in the X direction between the tilt driving permanent magnet and the tilt driving coil by energizing the tilt driving coil. The objective lens can be tilted around the X axis with high driving efficiency together with the lens holder via the movable substrate and the elastic support member.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a first embodiment of the present invention.
FIG. 2 is an exploded perspective view showing the first embodiment of the present invention.
FIG. 3 is a perspective view showing a second embodiment of the present invention.
FIG. 4 is a perspective view showing a third embodiment of the present invention.
FIG. 5 is a perspective view showing a conventional optical head actuator.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Fixed member 2,20,21,22,23,24,25,26 ... Permanent magnet 31 for driving, 32, 33, 34 ... Elastic support member 4 ... Lens holder 5 ... Objective lens 6, 60, 61, 62 ... Tracking coil 7, 70, 71, 72 ... Focus coil 8 ... Yoke 9 ... Movable substrate 10a, 10b, 101 ... Permanent for tilt drive Magnet 11, 111, 112 ... Tilt drive coil 14 ... Conductor

Claims (7)

In an XYZ Cartesian coordinate system where the X direction is the tangential direction, the Y direction is the radial direction, and the Z direction is the optical axis direction, one end of a plurality of elastic support members that extend substantially in the X direction and support the lens holder is fixed. A fixing member that is separated from the lens holder and the fixing member, and is supported by suspension on at least two elastic support members, a tracking coil for driving the lens holder in the Y direction, A focus coil for driving the lens holder in the Z direction, a permanent magnet for tilt driving for driving the lens holder in the tilt direction, and a tilt driving coil formed separately from the tracking coil and the focus coil And comprising
The tilt driving permanent magnet is disposed on one of the fixed member and the movable substrate, and the tilt driving coil is disposed on the other, respectively .
A magnetic field in the X direction is formed by the tilt driving permanent magnet whose magnetic pole surface faces in the X direction, and the tilt driving coil is disposed to face the magnetic pole surface of the tilt driving permanent magnet in the X direction ,
An optical head actuator , wherein a coil line segment of the tilt driving coil is exposed to an X-direction magnetic field springed out from the tilt driving permanent magnet . A magnetic field in the X direction is formed by the tilt driving permanent magnet, and the tilt driving coils form a pair so as to extend in the same direction in either the Y direction or the Z direction and be adjacent to each other. The optical head actuator according to claim 1 . A magnetic field in the X direction opposite to each other is formed by the adjacent tilt driving permanent magnets in pairs in the Y direction or the Z direction, and the tilt driving permanent magnets adjacent to each other in which the tilt driving coils form a pair. The optical head actuator according to claim 1, wherein the optical head actuator is formed to extend in a direction. A fixing member of the elastic support member, and wherein the elasticity and the supporting portion of the movable substrate support member, at least any one place between the fixing member and the movable substrate is provided with a cushioning member The optical head actuator according to claim 1 , 2 or 3 . The optical head actuator according to claim 4 , wherein the buffer member is formed of a gel polymer material. The cushioning member according to claim 4, characterized in that said a conductor fixed to the fixing member is formed on Kyosuki portion of said coil segment of the permanent magnet for the tilt drive said tilt driving coil The optical head actuator described in 1. 4. The optical head actuator according to claim 1 , wherein a magnetic yoke is provided on the back side of the tilt driving coil.

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