JP2000339721A - Objective lens supporting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently absorb vibration energy relating to pitching and yawing of an objective lens and to stably irradiate a light beam spot on the information recording surface of a recording medium. SOLUTION: In an XYZ orthogonal coordinate system of this supporting device, an objective lens 5 having an optical axis in a Z axis direction is suspended from and supported by a supporting base plate 101a so as to be movable in a Y axial direction and the Z axial direction through two pairs of elastic supporting members 3 which are paired in the Y axial direction, are adjacent to the Z axial direction and are extended in the X axial direction. In this case, respective ends of the supporting base plate 101a side of the elastic supporting member 3 are connected to a connecting pattern 120 provided so as to close at least one part of one side opening part of a through hole 140 formed in the supporting base plate 101a toward the X axial direction and also a damping member 100 is filled into the through hole 140.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a compact disc (CD), a digital versatile disc (DV)
D) A driving direction for driving an objective lens used for recording and reproducing information on a recording medium such as an optical disc such as an optical disc such as a mini disc (MD) or the like in a predetermined direction. And an objective lens supporting device for movably supporting the objective lens.

[0002]

2. Description of the Related Art As a conventional objective lens driving device, for example, there is one shown in a perspective view and a partially exploded perspective view in FIGS. 8 and 9, respectively. This objective lens driving device is a so-called four-wire supporting type moving coil system. A pair of support substrates 1a provided on a support base 1b are formed in the Y-axis direction and adjacent to the X-axis direction in the X-axis direction. Of the filament extending in the direction, for example, through a process such as a drawing process
One end of each of the two pairs of elastic support members 3 made of a u-Be alloy, a Cu-P alloy, or the like is fixed at a position separated by a predetermined distance such as a vertex of a rectangle, for example. The other end of the member 3 is fixed to the lens holder 4, and the objective lens 5 held by the lens holder 4 crosses an information pit row (track) of a disc-shaped recording medium (not shown) in a direction parallel to, for example, a radial direction (Y). Axis) and a focus (Z) substantially parallel to the optical axis of the objective lens 5.
).

Here, the support substrate 1a of each elastic support member 3
As shown in FIG. 10 as a partial cross-sectional view, the side end is made of Cu or the like provided on one side surface of the support substrate 1a through a through hole 14 that is cut so that the support substrate 1a can pass through. It is fixed to the metal film 12 by a connection member 13 made of solder or the like. Also, on the other side surface of the support substrate 1a,
Through-hole 1 drilled to the extent that elastic support member 3 can pass through
5 is formed, and the damping member 10 is filled in the filling container 9.

In FIG. 8, a support base 1b is provided with a magnetic yoke 8a made of, for example, Fe, Ni, Co, an alloy containing them, or ferrite. As shown in FIG. 9, the magnetic yoke 8a is connected to two legs that are spaced apart in the tangential (X-axis) direction and stand in the focus direction, and one end of these legs in the focus direction. It has a substantially U-shape having a return path portion 8r. This magnetic yoke 8a
Two legs made of, for example, an Nd-Fe-B alloy or the like are arranged so that different magnetic poles are opposed to the inner surfaces of the two legs by the air gap G on the inner surfaces of the two legs. Are provided respectively. Further, the other ends of the two legs of the magnetic yoke 8a are substantially I
Are connected to each other via a magnetic cover 8b in the shape of a letter,
These magnetic yoke 8a, magnetic cover 8b and drive permanent magnet 2 form a magnetic circuit having a closed magnetic path passing through the gap G and the return path portion 8r and a closed magnetic path passing through the gap G and the magnetic cover 8b.

The lens holder 4 has an opening 4
a, a tracking coil 6 for driving the objective lens 5 in the tracking direction to position the optical axis of the objective lens 5 on the center line of a desired track on the recording medium; A focusing coil 7 for focusing the lens 5 on the information pit surface is provided. The focusing coil 7 is provided to be wound around a bobbin 11 made of resin or the like around an axis in the focus direction.
1, the tracking coil 6 and the bobbin 11 to which the focusing coil 7 is mounted are wound around an axis in the tangential direction, and a bobbin 11 on which the focusing coil 7 is mounted extends in the tracking direction of the focusing coil 7. And the tracking coil 6
Is fixed to the opening 4a of the lens holder 4 so as to be positioned in the gap G of the magnetic circuit, and the tracking coil 6 and the focusing coil 7 and the magnetic circuit drive means Is composed.

In this way, the focusing coil 7
When a current flows through the focusing coil 7 in the tracking direction and the magnetic flux in the tangential direction of the driving permanent magnet 2 interacts with the focusing coil 7, an electromagnetic force in the focusing direction is generated in the focusing coil 7, and the lens holder is turned on. The objective lens 5 is displaced in a direction substantially parallel to the optical axis, that is, in a focus direction substantially perpendicular to the recording surface of a recording medium (not shown).

Similarly, when the tracking coil 6 is energized, an interaction between a current flowing through the tracking coil 6 in the focusing direction and a magnetic flux in the tangential direction by the driving permanent magnet 2 causes the tracking coil 6 to pass through the tracking coil 6 in the tracking direction. The electromagnetic force is generated to displace the lens holder 4 and thus the objective lens 5 in parallel with the tracking direction across the track of the recording medium (not shown).

Since the above-mentioned objective lens driving device has a suspension support structure by the elastic support member 3, it is, for example, a shaft sliding type objective lens driving device which is another typical support structure. When the movable part including the lens holder and the like is displaced, there is no friction with the shaft part,
Smooth and high-resolution driving becomes possible. However, the movable part suspended and supported by the four elastic support members 3
Since it is configured as a vibration system corresponding to a sliding beam whose bending shape is S-shaped and generates lateral vibration and a tip-added mass fixed to its tip, due to external vibration or impact,
As linear vibration in the tracking direction, focus direction or tracking / focus combined direction, and as torsional vibration around the axis oriented in the tangential direction,
For example, the structure is easy to resonate in a band of several tens Hz.

For this reason, normally, a vibration damping means comprising a filling container 9 arranged in contact with the side surface of the supporting substrate 1a on the movable portion side and a vibration damping member 10 filled therein is provided.
The vibration energy described above is absorbed. That is, as shown in detail in FIG. 10, a vibration damping member 1 having a large loss
0 is injected and filled so as to surround the elastic support member 3 fixed to the metal film 12 and extending in the tangential direction, so that the vibration energy due to the flexural resonance of the elastic support member 3 is sheared by the vibration damping member 10. By absorbing and converting it into heat, the vigorous resonance motion of the movable part is suppressed.

[0010]

However, the vibration of the movable part is not limited to the lateral vibration of the elastic support member 3 as described above.
11A, the movable portion rotates and vibrates (pitches) around the Y axis, and the elastic support members 3 adjacent to each other in the focus direction alternately expand and contract, or as shown in FIG. Is likely to rotate (yaw) around the Z axis, and resonance occurs in which the elastic support members 3 adjacent in the tracking direction alternately expand and contract. In particular, since the tracking coil 6 and the focusing coil 7 in which a plurality of turns are involved have a considerable bundle thickness, each driving point must be present at a different position in the tangential direction, and the tangent of the movable portion is required. It is extremely difficult to match all the positions of the center of gravity in the tangential direction with the tangential positions of the driving points of the tracking coil 6 and the focusing coil 7 in the tangential direction. For this reason, for example, if an attempt is made to drive in the tracking direction or the focus direction with an acceleration that includes a frequency band component corresponding to the above-described pitching or yawing resonance frequency, the rotational moment is applied around the Y axis or Z axis to the movable portion. And the operation becomes unstable.

However, in the above-described vibration damping means, since the vibration damping member 10 is unlikely to generate effective shear deformation, the elastic support member 3 associated with such pitching and yawing is used.
Vibration energy cannot be sufficiently absorbed for the expansion and contraction of For this reason, the size and density of the light beam spot irradiated on the information recording surface of the recording medium fluctuates due to the vibration of the focal position of the recording and / or reproducing light beam due to these vibrations, and the like. Recording cannot be performed, or the return light from the recording medium becomes unstable, so that the drive control ability is reduced, the jitter of the reproduced signal is generated, the S / N is reduced, and the performance of the optical head is impaired.

An object of the present invention has been made in view of such a conventional problem, and it is possible to efficiently absorb vibration energy relating to pitching and yawing of an objective lens, and to apply a light beam to an information recording surface of a recording medium. An object of the present invention is to provide an objective lens supporting device capable of stably irradiating a spot.

[0013]

In order to achieve the above-mentioned object, the present invention according to claim 1 is to provide an objective lens having an optical axis in the Z-axis direction in an XYZ orthogonal coordinate system, and a pair of objective lenses in the Y-axis direction. An objective lens supporting device that is suspended and supported on a support substrate movably in a Y-axis direction and a Z-axis direction via two pairs of elastic supporting members extending in the X-axis direction adjacent to the axial direction. Each end of the support substrate is connected to a connection pattern provided so as to cover at least a part of an opening on one side of a through hole formed in the support substrate in the X-axis direction. The interior is filled with a vibration damping member.

According to the first aspect of the present invention, the connection pattern provided in the opening on one side of the through-hole is bent and deformed with the pitching and yawing of the objective lens, so that the elastic support member becomes large in the X-axis direction. It becomes easy to be displaced. Thus, the shearing force generated between the connection pattern or the elastic support member and the through-hole wall causes a shear deformation of the damping member filled in the through-hole, thereby absorbing vibration energy applied to pitching and yawing. It becomes possible.

According to a second aspect of the present invention, in the objective lens supporting device according to the first aspect, a filling container for a vibration damping member is formed on the supporting substrate in contact with the other opening of the through hole, and the filling is performed. The vibration damping member is filled in the container and the through hole.

According to the second aspect of the present invention, in addition to the vibration energy of bending deformation of the connection pattern due to pitching and yawing of the objective lens and displacement of the elastic support member in the X-axis direction, the Y-axis direction, the Z-axis direction, or It is also possible to absorb the vibration energy of the elastic deformation of the elastic support member in each direction due to linear displacement in the combined direction of the Y-axis and Z-axis and torsion around the axis in the X-axis direction.

According to a third aspect of the present invention, in the objective lens supporting device according to the second aspect, a plurality of damping members having different effective damping bands are provided in the extending direction of the elastic supporting member. It is characterized by being filled continuously.

According to the third aspect of the present invention, the vibration band relating to the pitching and yawing of the objective lens, the linear displacement in the Y-axis direction, the Z-axis direction, the combined direction of the Y-axis and the Z-axis, and the X-axis direction. For each of the bands related to the vibration that causes torsion around the axis, it is possible to appropriately fill multiple vibration damping members with exceptionally large loss elastic modulus, so that energy can be more effectively applied to each vibration. It becomes possible to absorb.

In this way, it is possible to suppress changes in the size and density of the light beam spot irradiated on the information recording surface of the recording medium, and to provide a stable objective lens support device.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 show an objective lens driving device according to a first embodiment of the present invention. FIG. 1 is a perspective view, and FIG. 2 is a sectional view of a main part. Here, the same members as those in the conventional example are denoted by the same reference numerals, and their arrangements and directions are unified based on the same coordinate system as in the conventional example.

This objective lens driving device is a four-wire supporting type moving coil system similar to that shown in the conventional example, and includes a support substrate 101 provided on a support base 1b.
a is formed of a linear Cu—Be alloy, Cu—P alloy, or the like that has a pair in the Y-axis direction and extends in the X-axis direction adjacent to the Z-axis direction, for example, through a process such as drawing. One end of each of the pair of elastic support members 3 is fixed at a position separated by a predetermined distance, such as a vertex of a rectangle, and the other end of each of the two pairs of elastic support members 3 is fixed to the lens holder 4. Then, the objective lens 5 held by the lens holder 4 traverses an information pit row (track) of a disk-shaped recording medium (not shown), for example, tracking (Y) parallel to the radial direction.
(Axial direction) and a focus (Z axis) direction substantially parallel to the optical axis of the objective lens 5.

Here, the supporting substrate 10 of each elastic supporting member 3
The end on the 1a side is, as shown in detail in FIG.
01a, through a through hole 140 penetrating in the tangential direction, to a connection pattern 120 made of, for example, Cu or an alloy thereof provided on one side surface of the support substrate 101a so as to close the opening of the through hole 140. For example, it is fixed by a connection member 13 made of solder, adhesive, or the like. Further, the inside of the through hole 140 is filled with the filling member 100 so as to surround the elastic support member 3, so that the vibration damping member 100 is sheared by the deformation of the connection pattern 120 or the displacement of the elastic support member 3. .

On the support base 1b, for example, Fe, Ni,
Two legs made of Co, or an alloy containing them, or ferrite, which stand apart in the tangential (X-axis) direction and stand in the focus direction, and interconnect one end of these legs in the focus direction. U-shaped magnetic yoke 8 having a return path portion 8r
a is provided. The magnetic yoke 8a is disposed such that both legs intrude into the opening 4a of the lens holder 4, and different magnetic poles are opposed to the inner surfaces of the legs via a gap G.
For example, two drive permanent magnets 2 each made of an Nd—Fe—B alloy or the like are provided. Further, the other ends of the two legs of the magnetic yoke 8a are connected to a magnetic cover 8 having a substantially I-shape.
b, the magnetic yoke 8a, the magnetic cover 8b and the driving permanent magnet 2 form a closed magnetic path passing through the gap G and the return path portion 8r and a closed magnetic path passing through the gap G and the magnetic cover 8b. Forming a magnetic circuit.

The lens holder 4 has an opening 4
a, a tracking coil 6 for driving the objective lens 5 in the tracking direction to position the optical axis of the objective lens 5 on the center line of a desired track on the recording medium; A focusing coil 7 for focusing the lens 5 on the information pit surface is provided. The focusing coil 7 is provided around a bobbin 11 made of resin or the like wound around an axis in the focus direction.
The tracking coil 6 is wound around the bobbin 11 around the axis in the tangential direction and provided outside the focusing coil 7. The tracking coil 6 and the bobbin 11 on which the focusing coil 7 is mounted extend in the tracking direction of the focusing coil 7. And the conducting wire portion extending in the focus direction of the tracking coil 6 is fitted and fixed in the opening 4a of the lens holder 4 so as to be positioned in the gap G of the magnetic circuit. The driving means is constituted by the focusing coil 7 and the magnetic circuit.

In this manner, the focusing coil 7
When a current flows through the focusing coil 7 in the tracking direction and the magnetic flux in the tangential direction of the driving permanent magnet 2 interacts with the focusing coil 7, an electromagnetic force in the focusing direction is generated in the focusing coil 7, and the lens holder is turned on. 4 and, consequently, the objective lens 5 is displaced in a direction substantially parallel to its optical axis, that is, in a focus direction substantially perpendicular to the recording surface of a recording medium (not shown).

Similarly, when the tracking coil 6 is energized, an interaction between a current flowing through the tracking coil 6 in the focusing direction and a magnetic flux in the tangential direction by the driving permanent magnet 2 causes the tracking coil 6 to pass through the tracking coil 6 in the tracking direction. An electromagnetic force is generated to displace the lens holder 4 and, consequently, the objective lens 5 in a direction parallel to a tracking direction across a track of a recording medium (not shown).

According to this embodiment, the tracking coil 6 and the focusing coil 7 are supplied with an alternating current including a component of a band corresponding to the resonance frequency of the pitching or yawing, so that the lens holder 4, the objective lens 5, When an acceleration is applied to the movable part including the tracking coil 6 and the focusing coil 7, the movable part is rotated around the Y axis and Z.
Rotationally oscillates around the axis, and at the same time, the connection pattern 120 starts to bend and deform in the tangential direction, and the elastic support member 3 tends to largely displace in the tangential direction. However, since the damping member 100 is filled in the through hole 140 of the support substrate 101a so as to surround the elastic support member 3, the connection pattern 1 that has been bent or displaced.
The displacement between the elastic support member 20 and the through hole 140 and the elastic support member 3 causes shear deformation of the vibration damping member 100, thereby absorbing the energy of the vibration applied to pitching and yawing.

Therefore, the growth of vibration at the resonance frequency of pitching or yawing is suppressed, and it is possible to prevent undesired fluctuation of the light beam irradiated on the recording medium due to the vibration of the objective lens 5.

FIG. 3 is a sectional view showing a main part of a second embodiment of the present invention. This embodiment is different from the first embodiment in that a through hole 140 is formed on the side of the support substrate 101a opposite to the side on which the connection pattern 120 is provided.
The filling container 9 is formed in contact with the opening of the filling container 9.
The inside and the inside of the through hole 140 are filled with the damping member 100, respectively. With this configuration, the vibration damping member 10
A value of 0 can absorb not only the bending of the connection pattern 120 and the displacement of the elastic support member 3 but also the energy of vibration caused by the bending deformation of the elastic support member 3 as in the conventional example.

As shown in FIGS. 4A and 4B as a modification, for example, a through hole 1 adjacent in the focus direction is provided.
The through-holes 141 may be integrated by connecting the 40s to each other. Furthermore, the connection pattern 120 is partially cut off as shown in, for example, FIGS. 5A and 5B without closing the entire opening of the through hole 141 integrated in the focus direction on the connection pattern 120 side. For example, it may be formed in an overhang shape. 4 (b) and 5 (b)
In each of the, in order to visually recognize the through hole 140,
Each of the filling containers 9 is indicated by a broken line.

Alternatively, instead of forming the connection pattern 120 as a single unit, as shown in FIG.
The connection pattern 120 may be formed at a predetermined position 01a via a flexible polymer film 121 made of polyimide or the like.

FIG. 7 is a sectional view showing a main part of a third embodiment of the present invention. This embodiment is different from the second embodiment in that the inside of the filling container 9 and the support substrate 101a
Is filled with a damping member 110 and a damping member 111 having an effective damping band different from the damping member 110 in the extending direction of the elastic support member 3. Here, as the damping member 110, a member having a large loss elastic modulus particularly in a band including the resonance frequency of pitching and yawing of the movable portion is selected. A band having a large loss elastic modulus in a band including a resonance frequency such as vibration in the tracking direction is selected.

Therefore, according to the third embodiment, the displacement of the elastic support member 3 in the tangential direction due to the pitching and yawing of the movable portion, and also the displacement of the movable portion in the focus direction and tracking direction. Energy can be effectively absorbed for each of the elastic deformations of the elastic support members 3 due to vibrations and the like.

[0034]

As described above, according to the present invention, each pair of the elastic support members on the support substrate side of two pairs of elastic support members extending in the X-axis direction adjacent to each other in the Y-axis direction and adjacent in the Z-axis direction. Is connected to a connection pattern provided so as to close one opening of a through hole formed in the support substrate in the X-axis direction, and the inside of the through hole is filled with a vibration damping member. Due to pitching or yawing of the objective lens suspended and supported in the Y-axis direction and the Z-axis direction by the support member, the connection pattern is bent and deformed in place of the expansion and contraction of the elastic support member, and the elastic support member moves in the X-axis direction. Large displacement easily occurs. Accordingly, a shear deformation is caused in the vibration damping member due to a displacement generated between the connection pattern and the elastic support member and the through-hole wall, so that energy of vibration applied to pitching and yawing can be absorbed.

Further, a filling container is formed in the supporting substrate in contact with the opening on the other side of the through hole of the supporting substrate, and the damping member is filled in the filling container and the through hole. Due to the shearing deformation, in addition to the bending energy of the connection pattern due to the pitching and yawing of the objective lens and the vibration energy of the displacement of the elastic support member in the X-axis direction, the Y-axis direction, the Z-axis direction, or the Y-axis / Z-axis The vibration energy of the bending deformation of the elastic supporting member due to the linear displacement in the combining direction and the twist around the axis in the X-axis direction can also be absorbed.

Further, by filling a plurality of vibration-damping members having different effective vibration-damping bands in the extending direction of the elastic support member as vibration-damping members, a vibration band causing pitching and yawing of the objective lens can be obtained. , A plurality of systems each having a particularly large loss elastic modulus in each of the vibration bands that cause linear displacement in the Y-axis direction, the Z-axis direction or the combined direction of the Y-axis and the Z-axis, and torsion around the axis in the X-axis direction. Since the vibration member can be selected and filled, energy can be more effectively absorbed for each vibration.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a first embodiment of the present invention.

FIG. 2 is a sectional view of a main part of FIG.

FIG. 3 is a sectional view of a main part showing a second embodiment of the present invention.

FIGS. 4A and 4B are a main part sectional view and a main part perspective view showing a modification of the second embodiment.

FIG. 5 is a cross-sectional view of a main part and a perspective view of a main part showing another modification of the second embodiment.

FIG. 6 is a cross-sectional view of a principal part showing still another modified example of the second embodiment.

FIG. 7 is a sectional view of a principal part showing a third embodiment of the present invention.

FIG. 8 is a perspective view showing a conventional example.

9 is a partially exploded perspective view of FIG.

FIG. 10 is a partial sectional view of FIG.

FIG. 11 is a diagram for explaining the operation of the conventional example.

[Explanation of symbols]

 Reference Signs List 3 elastic support member 4 lens holder 5 objective lens 9 filling container 100, 110, 111 damping member 101a support substrate 120 connection pattern 140 through hole

Claims (3)

[Claims] In an XYZ orthogonal coordinate system, two pairs of elastic support members extending in the X-axis direction adjacent to each other in the Z-axis direction are paired with the objective lens having the optical axis in the Z-axis direction. An objective lens supporting device that is suspended and supported on a supporting substrate so as to be movable in the Y-axis direction and the Z-axis direction through the support member, wherein each end of the elastic supporting member on the supporting substrate side is directed to the supporting substrate in the X-axis direction. An objective lens supporting device connected to a connection pattern provided so as to cover at least a part of one side opening of the through hole formed as described above, and a damping member is filled in the through hole. 2. A filling container of a vibration damping member is formed on the support substrate in contact with an opening on the other side of the through hole, and the damping member is filled in the filling container and the through hole. The objective lens support device according to claim 1, wherein 3. The objective lens according to claim 2, wherein a plurality of vibration-damping members having different effective vibration-damping bands are connected in the extending direction of the elastic support member as the vibration-damping member. Support device.