JPH08221776A - Lens driving device - Google Patents

Abstract

PURPOSE: To miniaturize a movable part having an objective lens in a focusing direction and to prevent the resonance of the movable part. CONSTITUTION: One elastic supporting member 11 positioned on the incident side of a laser beam 18 in a tracking direction with respect to the objective lens 13 and positioned on a reflection mirror 5 side in the focusing direction is made to offset to a fixed member 32 side in the tangential direction. The movable part 51 is miniaturized in the focusing direction by preventing the elastic supporting member 11 from interfering in a laser beam 18. Furthermore, another elastic supporting member 9 is made to offset to a reverse side by the same distance, thereby, the moment of two offset elastic supporting members 9 and 11 is cancelled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens driving device for driving an objective lens in a tracking direction and a focusing direction.

[0002]

2. Description of the Related Art An optical disk player optically reads and reproduces recorded information on a rotationally driven optical disk.
At this time, in order to satisfactorily read the recorded information on the optical disc,
The objective lens is driven in the tracking direction and the focus direction by the lens driving device.

A first conventional example of such a lens driving device 1 will be described below with reference to FIG. Here, the optical disc 2 is arranged horizontally, the focus direction is the vertical direction, the tracking direction is the horizontal direction, and the tangential direction is the front-back direction.

First, the reflection mirror 5 is arranged at the center of the main body base 3 which is horizontally arranged.
, The reflecting surface 6 is inclined at 45 ° and faces the upper side and the right side. A rectangular fixed member 7 that is flat in the left-right direction is mounted on the rear portion of the main body base 3, and four wires 8 to 11, which are elastic support members, project forward from the four corners of the front surface of the fixed member 7. It is set up. A lens holder 12 is attached to the tips of these wires 8 to 11, and an objective lens 13 is fixed to the center of the upper surface of the lens holder 12.

That is, the four wires 8 to 11 have the same length and are elongated in the tangential direction, and two wires are located on each side of the objective lens 13 in the tracking direction.
In the focusing direction, two objective lenses 13 are located on each side and below the objective lens 13. The objective lens 13 is movably supported by the wires 8 to 11 in the focusing direction and the tracking direction, and faces the optical disc 2 from below.

The lens holder 12 has connecting portions 14 projecting from the upper and lower portions of the side surfaces on both sides, and the wires 8 to 11 are connected to these connecting portions 14. The lens holder 12 is formed in a hollow structure, and opening holes 15 and 16 communicating with the objective lens 13 are formed in the lower surface and the right side surface. Since the reflection mirror 5 is inserted through the opening 15 in the lower surface of the lens holder 12 and positioned inside, the reflection surface 6 of the reflection mirror 5 is the objective lens 1.
3 and the opening hole 16 on the right side surface.

A beam splitter, a laser light source, a light receiving element (neither shown), etc. are arranged at a position facing the opening 16. A lens driving mechanism (not shown) for displacing the lens holder 12 in the focus direction and the tracking direction is formed by, for example, a magnet attached to the lens holder 12 and a coil fixed to the main body base. ing. By mounting the components of the lens driving mechanism and the objective lens 13 on the lens holder 12 in this way, a movable portion 17 that is displaceable in the focus direction and the tracking direction is formed.

In such a structure, the laser light 18 emitted from the laser light source is incident on the opening 16 of the lens holder 12 from the right through the beam splitter and is deflected upward by the reflecting surface 6 of the reflecting mirror 5. , Objective lens 1
3 converges on the track of the optical disc 2.

The laser beam 18 reflected by the optical disk 2 is incident on the objective lens 13 from above, is deflected to the right by the reflecting surface 6 of the reflecting mirror 5, and is emitted from the opening 16 of the lens holder 12. , This laser light 1
The recorded information on the optical disk 2 can be read by deflecting 8 by the beam splitter and reading by the light receiving element.

At this time, in order to properly focus the laser light on the track of the optical disk 2, the movable portion 17 is displaced in the focus direction and the tracking direction by the magnetic attractive force of the lens driving mechanism, and the focus adjustment and tracking adjustment of the objective lens 13 are performed. And. In order to perform such displacement of the objective lens 13 quickly and smoothly, the four wires 8 to
The movable portion 17 is supported by 11 so as to be movable in the focus direction and the tracking direction.

[0011]

In the lens driving device 1 as described above, the movable portion 17 is moved by the four wires 8 to 11 in order to displace the objective lens 13 quickly and smoothly in the focus direction and the tracking direction. It is movably supported in the focus direction and the tracking direction.

However, since the two wires 9 and 11 located on the right side of the lens holder 12 are separated in the vertical direction so as not to interfere with the laser beam 18, the lens holder 1
2 is upsized in the vertical direction.

Further, the laser light 1 is applied to the lens holder 12.
Although the opening hole 15 through which the lens 8 is inserted is formed, the productivity of the lens holder 12 is reduced by forming such an opening hole 15.

Further, since the lens holder 12 is formed with the opening 15 only on the right side, the weight balance of the movable portion 17 is not symmetrical, and there is a concern that an unnecessary moment acts upon displacement to cause resonance. is there. For example, the movable part 17
In order to make the weight balance of the lens symmetrical,
It is possible to form an opening on the left side of 2, but it is not preferable because an unnecessary opening causes stray light.

Further, since the lens driving mechanism displaces the movable portion 17 in the focus direction and the tracking direction by the magnetic attractive force, it has a structure for individually generating the magnetic attractive force in these directions. However, in this case, one leakage magnetic flux acts on the other, and resonance may occur in the movable portion 17.

Therefore, in the lens driving device 1 described above,
In order to reduce deterioration of optical characteristics due to resonance, the movable portion 17
The objective lens 13 is arranged at the center of. However, since the incident optical path of the laser light 18 is located at the center of the movable portion 17 in this case, it is necessary to separate the two wires 9 and 11 in the vertical direction so as not to interfere with the laser light 18.
The lens holder 12 is upsized in the vertical direction.

Japanese Patent Application Laid-Open No. 4-103038 discloses prevention of resonance due to magnetic flux leakage as described above. The lens drive device 19 disclosed in this publication will be described below as a second conventional example with reference to FIG.

First, the movable portion 2 of the lens driving device 19
In 0, the objective lens 13 is arranged at a position decentered from the center of the lens holder 21, and the lens driving mechanism 22 is provided at the center of the lens holder 21. In the lens driving mechanism 22, the opening hole 2 of the lens holder 21
Tracking coil 24 and focusing coil 2
5 and the pair of magnets 26 are supported by the yoke 27.

In such a structure, the yoke 27 is made larger than the magnet 26 so that stress due to magnetic flux leakage does not act on the movable portion 20 to prevent resonance.

However, although the yoke 27 is larger than the magnet 26, the lens holder 21 is larger than the yoke 27.
It is necessary that the opening hole 23 of the
Since the objective lens 13 is located outside of, the movable part 20 becomes large.

Further, although the movable portion 20 is prevented from resonating due to the stress due to the magnetic flux leakage as described above, in reality, the magnetic flux leakage cannot be completely shut off and there are part errors and the like. Resonance may occur in the movable part 20. Since the objective lens 13 is arranged at a position decentered from the center of the movable portion 20, the adverse effect of resonance is great.

In the lens driving devices 1 and 19 described above, since the wires 8 to 11 are located on both sides of the objective lens 13, as shown in FIGS.
On the other hand, the wire 8 located on the inner peripheral side of the optical disc 2 in the tracking direction and on the optical disc 2 side in the focusing direction supports the turntable 100 supporting the optical disc 2.
Interfere with. Therefore, the moving range of the objective lens 13 is limited, it is difficult to access deep inside the optical disc 2, and the optical disc 2 cannot be used effectively.

[0023]

According to the first aspect of the present invention,
With respect to the movable part with the objective lens, four or more elastic supporting members elongated in the tangential direction and having the same length are arranged on both sides in the tracking direction and at plural positions in the focusing direction, and one end is used as a fixed member. The other end of the fixed elastic support member movably supports the movable portion in the focus direction and the tracking direction, and the objective lens is opposed to the optical disc. When the laser light incident from the tracking direction is deflected in the focus direction by the reflection mirror and is incident on the objective lens and converged on the track of the optical disc,
The movable part is displaced in the focus direction and the tracking direction by the lens driving mechanism.

One elastic support member located on the incident side of the laser beam in the tracking direction with respect to the objective lens and on the reflection mirror side in the focusing direction is offset by a fixed distance in the tangential direction to the fixed member side. As a result, this elastic support member is arranged at a position where it does not interfere with the laser light. Moreover, by offsetting the other one elastic support member to the opposite side in the tangential direction by the same distance, the moments of the two offset elastic support members are offset.

According to the second aspect of the invention, the four elastic supporting members are arranged on the both sides in the tracking direction with respect to the movable portion, and two elastic supporting members are arranged at the two positions in the focusing direction. On the other hand, one elastic supporting member located on the laser light incident side in the tracking direction and on the reflecting mirror side in the focusing direction is offset by a fixed distance to the fixed member side in the tangential direction. The support member is arranged at a position where it does not interfere with the laser light. Moreover, by offsetting the other elastic support member located on the laser light incident side in the tracking direction with respect to the objective lens to the opposite side in the tangential direction by the same distance, the two offset elastic The moments of the support members cancel out.

According to the third aspect of the present invention, four elastic supporting members are arranged on the both sides of the movable portion in the tracking direction, and two elastic supporting members are arranged at the two positions in the focusing direction. In contrast, the two elastic support members located on the laser light incident side in the tracking direction are offset by a fixed distance in the tangential direction toward the fixed member, so that the elastic support members are positioned so as not to interfere with the laser light. Will be placed. Moreover, by offsetting the two elastic support members located on the opposite sides in the tracking direction with respect to the objective lens to the opposite sides by the same distance in the tangential direction, the moment of the two offset elastic support members is Offset.

According to the fourth aspect of the invention, the four elastic supporting members are arranged on the both sides of the movable portion in the tracking direction, two elastic supporting members are arranged, and two elastic supporting members are arranged at two positions in the focusing direction. On the other hand, the two elastic support members located on the reflection mirror side in the focus direction are offset by a certain distance to the fixed member side in the tangential direction, so that the elastic support members are arranged at positions that do not interfere with the laser light. It Moreover, by offsetting the two elastic supporting members located on the opposite side in the focusing direction to the opposite side in the tangential direction with respect to the objective lens by the same distance, the moment of the two elastic supporting members thus offset is Offset.

According to a fifth aspect of the present invention, one elastic supporting member located on the inner peripheral side of the optical disk in the tracking direction with respect to the objective lens and on the optical disk side in the focusing direction is fixed in the tangential direction. The elastic support member is arranged at a position where it does not interfere with the turntable by offsetting it to the side by a certain distance. Moreover, by offsetting the other one elastic support member to the opposite side in the tangential direction by the same distance, the moments of the two offset elastic support members are offset.

According to the sixth aspect of the invention, the lens driving mechanism is disposed on both sides of the movable portion in the tangential direction, so that the lens driving mechanism does not interfere with the laser light.

According to the seventh aspect of the present invention, the displacement detecting sensor for detecting the displacement of the objective lens in the tracking direction is mounted in the vicinity of the concave portion of the lens holder. Offset by weight.

[0031]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention is shown in FIG.
The following description is based on FIG. Regarding the lens driving device 28 shown in the present embodiment, the same parts as those of the lens driving device 1 described as the first conventional example are denoted by the same names and reference numerals, and detailed description thereof will be omitted. Also,
Also in this embodiment, the optical disc 2 is arranged horizontally, the focus direction is the vertical direction, the tracking direction is the horizontal direction, and the tangential direction is the front-back direction.

First, as shown in FIGS. 1 and 2, yokes 30 are formed on the front and rear edges of the main body base 29 made of a magnetic metal sheet.
Are erected, and magnets 31 are attached to the inner surfaces of these yokes 30. A fixing member 32 is attached to a rear portion of the main body base 29, and four wires 8 to 11 which are elastic supporting members are protruded from four corners of the front surface of the fixing member 32 to the front. However, the fixing member 32
The right upper part 33 projects forward, the right lower part 34 projects rearward, and the wires 9 and 11 are attached to these parts.

The tips of the wires 8 to 11 are attached to the connecting portions 14, 36 and 37 of the lens holder 35,
The left connecting portion 14 is located beside the objective lens 13. However, the connecting portion 36 on the upper right side is located in front of the objective lens 13, and the connecting portion 37 on the lower right side is located behind the objective lens 13.

That is, the four wires 8 to 11 have the same length and are elongated in the tangential direction, two wires are located on each side of the objective lens 13 in the tracking direction, and one side and one side of the objective lens 13 in the focusing direction. Two of them are located on the incident side (right side) of the laser beam 18 in the tracking direction with respect to the objective lens 13 and on the side of the reflection mirror 5 (lower side) in the focusing direction with respect to the objective lens 13. The wire 11 is offset to the fixed member 32 side (rear side) by a constant distance 1 in the tangential direction and is positioned on the incident side (right side) of the laser beam 18 in the tracking direction with respect to the objective lens 13 (upper side). ) One wire 9
It is offset by the same distance 1 on the opposite side (front side) in the tangential direction.

The lens holder 35 is formed in a hollow structure whose lower surface is open, and a recess 38 facing the reflecting surface 6 of the reflecting mirror 5 is formed at the lower edge of the right side surface. The laser light 18 is incident on the concave portion 38 of the lens holder 35, but the connecting portion 37 opposes the incident optical path of the laser light 18 from behind without interference, and the wire 9 does not interfere from above. opposite.

Further, as shown in FIG. 3, the magnet 31 is provided with magnetizing portions 39 and 40 for tracking and focusing. The magnetizing portion 39 for tracking is magnetized by dividing the polarity into right and left, and the magnetizing portion 40 for focusing is magnetized by dividing the polarity in up and down. As shown in FIGS. 1 to 3, the magnet 31 is formed on the front and rear surfaces of the lens holder 35.
Tracking and focusing coils 41 and 42 are mounted at positions facing the magnetized portions 39 and 40, respectively. A lens drive mechanism 43 that displaces the lens holder 35 in the focus direction and the tracking direction by the coils 41 and 42 and the magnet 31.
Are formed.

Further, as shown in FIGS. 4 and 5, the objective lens 1 is provided near the concave portion 38 of the lens holder 35.
A displacement detection sensor 44 for detecting the displacement in the tracking direction 3 is attached.

More specifically, this displacement detection sensor 44
Is a U-shaped light blocking member 45 and one LED (Light Emi
and two light-receiving portions 47 and 48 are arranged side by side in the left-right direction. The light blocking member 45 is attached to the right edge of the upper and lower surfaces of the lens holder 35, and the recess 38
It projects from the front side to the right side. The LED 46 and the two-divided photodiode 49 are fixed to the upper surface of the main body base 29 by a U-shaped holder 50 elongated in the front-rear direction, and face each other via the light shielding member 45. The light blocking member 45 faces the incident optical path of the laser light 18 from the front without interference.

As described above, the objective lens 13 and the coils 41, 4 of the lens driving mechanism 43 are attached to the lens holder 35.
By mounting the light shielding member 45 of the displacement detecting sensor 44 or the displacement detecting sensor 44, a movable portion 51 that can be displaced in the focus direction and the tracking direction is formed.

In the lens driving mechanism 43, the magnetizing portions 39 and 40 and the coils 41 and 42 are positioned so as to be rotationally symmetrical with respect to the optical axis of the objective lens 13. The force does not generate a moment for rotating the movable portion 51 about the optical axis.

In such a structure, the laser light 18 emitted from the laser light source is incident on the concave portion 38 of the lens holder 35 from the right side via the beam splitter and is deflected upward by the reflecting surface 6 of the reflecting mirror 5. Objective lens 13
Is converged on the track of the optical disc 2.

The laser light 18 reflected by the optical disk 2 is incident on the objective lens 13 from above, is deflected to the right by the reflecting surface 6 of the reflecting mirror 5, and is emitted from the concave portion 38 of the lens holder 35. This laser light 18
The information recorded on the optical disk 2 can be read by deflecting the light beam by the beam splitter and reading it by the light receiving element.

At this time, the lens drive mechanism 43 drives the movable portion 51 in the tracking direction and the focus direction in order to properly focus the laser light on the track of the optical disk 2.

More specifically, the tracking error of the objective lens 13 is detected by a tracking sensor (not shown), and the magnetic attraction between the coil 41 of the lens driving mechanism 43 and the magnetized portion 39 of the magnet 31 is detected according to the detection result. By performing the adjustment, the movable portion 51 is displaced in the tracking direction to perform the tracking adjustment of the objective lens 13,
The objective lens 13 is made to follow the track of the optical disc 2.

At the same time, a focusing error of the objective lens 13 is detected by a focus sensor (not shown), and the magnetic attraction between the coil 42 of the lens driving mechanism 43 and the magnetized portion 40 of the magnet 31 is adjusted according to the detection result. By doing so, the movable portion 51 is displaced in the focus direction, the focus of the objective lens 13 is adjusted, and the focus of the objective lens 13 is positioned on the track of the optical disc 2.

When the track of the optical disk 2 is eccentric or the track of the optical disk 2 is spiral, when the objective lens 13 is made to follow the track only by the displacement of the movable section 51, the movable section 51 with respect to the main body base 29. Is largely displaced, the optical axis of the objective lens 13 is displaced from its original position, and the optical characteristics of the light receiving element and the light emitting element are deteriorated.

Therefore, in the above case, the entire lens driving device 28 is moved in the tracking direction by the tracking mechanism (not shown). Then, in order to perform the tracking movement of the lens driving device 28 in this way,
The displacement detection sensor 44 is movable part 5 with respect to the main body base 29.
The relative displacement of 1 is detected.

More specifically, as shown in FIG. 5, the light emitted from one LED 46 is incident on the two light receiving portions 47 and 48 of the two-divided photodiode 49 via the light shielding member 45. In the state where the relative displacement with respect to the main body base 29 is not generated, the incident light of the light receiving portions 47 and 48 is uniformly blocked by the light blocking member 45. In order to make the objective lens 13 follow the track of the optical disc 2, the movable portion 51
Is displaced in the tracking direction, the light shielding amount of the light receiving portion 47 or 48 in the displacement direction increases, and the light receiving portion 4 in the opposite direction is
Since the light receiving amount of 8 or 47 increases, these light receiving units 4
By comparing the outputs of 7 and 48, the relative displacement of the movable portion 51 with respect to the main body base 29 is detected.

Therefore, based on the detection result, the tracking mechanism moves the entire lens driving device 28 in the tracking direction, whereby the relative displacement of the movable portion 51 with respect to the main body base 29 is eliminated, and the objective lens 13 is eliminated. The optical axis of is also maintained at a good position.

In the lens driving device 28 described above, in order to perform the above-described displacement of the objective lens 13 quickly and smoothly, the movable portion 5 is connected by the four wires 8-11.
1 is movably supported in the focus direction and the tracking direction, but the wire 9 on the upper right side is offset forward, and the wire 11 on the lower right side is offset rearward. Therefore, the lower wire 11 does not interfere with the incident optical path of the laser light 18, and the lens holder 3
5 is downsized in the vertical direction. This lens holder 3
In FIG. 5, a concave portion 38 is formed in order to insert the incident optical path of the laser light 18, but this has a simple shape and is easy to manufacture as compared with the case of penetrating an opening hole.

The wire 9 on the upper right side is the wire 11
Since they are offset in the opposite direction by the same distance, the moments due to the bending of the wires 9 and 11 are offset, and unnecessary stress does not act on the movable portion 51 to cause resonance.

More specifically, when the movable portion 51 is displaced for tracking adjustment or focus adjustment, the wires 8 to 11 are bent, so that a reaction force acts on the movable portion 51.
Since the reaction force due to the bending of the wires 8 and 10 that are not offset acts on the center of gravity of the movable portion 51, no moment is generated in the movable portion 51. Offset wire 9,
Since the reaction force due to the bending of 11 acts on the position displaced from the center of gravity of the movable portion 51, moments act on the movable portion 51, but these moments have the same strength and opposite directions, so they are offset.

It is possible that a minute resonance may occur in the movable part 51 due to a component error or the like.
Since the objective lens 13 is disposed at the center of the optical axis, even if rotational resonance occurs in the movable portion 51 with the focus direction as the axial direction, the optical characteristics are not adversely affected.

Further, the coil 41 of the lens driving mechanism 43,
Since the magnet 42 and the magnet 31 are positioned in the front-rear direction of the lens holder 35, the movable portion 51 is miniaturized in the left-right direction without interfering with the incident optical path of the laser light 18.

Therefore, the objective lens 13 is attached to the optical disk 2
When moving from the outer periphery to the center of the optical disc 2, the chuck of the optical disc 2 and the spindle motor do not interfere with the movable portion 51, so that the objective lens 13 can be moved to the vicinity of the center of the optical disc 2. The recording surface can be effectively used.

Further, since the movable portion 51, which is downsized in the vertical and horizontal directions as described above, is lightweight, the responsiveness of the focus adjustment and the tracking adjustment is good, and the load on the lens drive mechanism 43 is reduced. ing.

Since the lens holder 35 has the concave portion 38 formed only on the right side for inserting the laser beam 18, the weight balance thereof is not symmetrical. However, the displacement detection sensor 4 is provided on the right side of the lens holder 35.
Since the light shielding member 45 of No. 4 is attached, the weight balance of the movable portion 51 is symmetrical. Therefore, when the movable portion 51 is displaced, no moment is generated due to the weight balance not being bilaterally symmetric, and the resonance of the movable portion 51 is well prevented.

Next, a second embodiment of the present invention will be described with reference to FIG.
And it demonstrates below based on FIG. Note that, regarding the lens driving device 52 shown here, the same parts as those of the lens driving device 28 described as the first embodiment are denoted by the same names and reference numerals, and detailed description thereof will be omitted.

In the lens driving device 52 of this embodiment,
The left portion 54 of the fixing member 53 projects forward from the right portion 55, and connecting portions 57 and 58 are formed on the right rear portion and the left front portion of the lens holder 56. Therefore, the four wires 8 to 11 are the two wires 9 and 11 located on the incident side (right side) of the laser light 18 in the tracking direction with respect to the objective lens 13, and the fixing member 53 in the tangential direction.
Offset to the side (rear side) by a fixed distance l ',
Two wires 8 and 10 located on the opposite side (left side) in the tracking direction with respect to the objective lens 13 are offset on the opposite side (front side) in the tangential direction by the same distance l ′.

Further, the laser light 18 is incident on the concave portion 38 of the lens holder 56, and the connecting portion 57 is opposed to the incident optical path of the laser light 18 from the rear without interference.

By mounting the objective lens 13, the coils 41 and 42 of the lens driving mechanism 43, and the light shielding member 45 of the displacement detection sensor 44 on the lens holder 56, a movable portion that is displaceable in the focus direction and the tracking direction. 59 are formed.

In such a structure, the lens driving device 52 described above functions similarly to the lens driving device 28 described above. That is, since the left wires 8 and 10 and the right wires 9 and 11 are offset in the opposite direction by the same distance, the moments due to the bending of these wires 8 to 11 are offset, and unnecessary in the movable portion 59. Resonance does not occur due to various stresses.

Moreover, in this lens driving device 52, both the right two wires 9 and 11 are offset rearward, so that not only the lower wire 11 but also the upper wire 9 is incident on the optical path of the laser beam 18. Without interfering with
The lens holder 56 can be made extremely thin.

In the lens driving device 52, the wires 8 to 11 are shown to be arranged in parallel with the tangential direction, but the present invention is not limited to the above method and is shown in FIG. As described above, the lens driving device 61 in which the fixing member 60 is formed wider than the lens holder 56 and the wires 8 to 11 are trapezoidally arranged can be realized. In such a lens driving device 61, since the spring constant of rotation with the tangential direction as the axial center direction is large, resonance of the movable portion 59 in such a direction can be prevented.
Further, arranging the wires 8 to 11 in the trapezoidal shape in this manner allows the lens driving device 2 described above as the first embodiment.
8 and a lens driving device 62 described later as a third embodiment.

Next, a third embodiment of the present invention will be described with reference to FIG.
And it demonstrates below based on FIG. With regard to the lens driving device 62 shown here, the same parts as those of the lens driving device 28 described as the first embodiment are denoted by the same names and reference numerals, and detailed description thereof will be omitted.

In the lens driving device 62 of this embodiment,
The upper portion 64 of the fixing member 63 projects forward from the lower portion 65, and connecting portions 67 and 68 are formed on the right side and left side of the lens holder 66 at the upper front side and the lower rear side. Therefore, the four wires 8 to 11 are the two wires 10 and 11 located on the reflection mirror 5 side (lower side) in the focusing direction with respect to the objective lens 13 and the fixing member 63 side (the tangential direction). The two wires 8 and 9 which are offset to the rear side) by a fixed distance l ″ and are located on the opposite side (upper side) in the focusing direction with respect to the objective lens 13 are on the opposite side (front side) in the tangential direction. Offset by the same distance.

By mounting the objective lens 13, the coils 41 and 42 of the lens driving mechanism 43, and the light shielding member 45 of the displacement detection sensor 44 on the lens holder 66, the lens holder 66 can be displaced in the focus direction and the tracking direction. The movable portion 69 is formed.

In such a structure, the above-mentioned lens driving device 62 functions similarly to the above-mentioned lens driving device 28 and the like. That is, since the wire 11 on the lower right side is offset rearward, this wire 11 is
Lens holder 66 without interfering with the incident light path of
Has been made thinner. Further, since the upper wires 8 and 9 and the lower wires 10 and 11 are offset in the opposite directions by the same distance, the moment due to the bending of these wires 8 to 11 is offset, and the movable portion 69 Resonance does not occur due to unnecessary stress.

In the lens driving device 62, since the upper wires 8 and 9 are offset forward as described above, as shown in FIG. 10, the length L in the front-rear direction of the portion protruding upward is increased. ″ Is shortened. Therefore, the lens driving device 62 is suitable for the disc cassette 70. That is, the disc cassette 70 is, as shown in FIG.
Since the opening 72 is formed in the lens holder 1, the lens driving device 62 sets the objective lens 13 to the opening 7 of the cassette case 71.
The optical disc 2 is arranged to face the optical disc 2.

Therefore, if the front-rear length L ″ of the portion protruding above the lens driving device 62 is short, this portion can be arranged in the opening 72 of the disc cassette 70.
The objective lens 13 can be easily opposed to the optical disc 2. Therefore, the lens driving device 62 described above can be applied to the magneto-optical disk 2 of 3.5 to 2.5 inches, which is remarkably miniaturized.

Next, a fourth embodiment of the present invention will be described with reference to FIG.
1 and FIG. 12 will be described below. With respect to the lens driving device 73 shown here, the same parts as those of the lens driving device 28 described as the first embodiment are denoted by the same names and reference numerals, and detailed description thereof will be omitted.

In the lens driving device 73 of this embodiment,
The left upper part 75 of the fixing member 74 projects rearward, and the left lower part (not shown) projects forward.
A connecting portion 77 and the like are formed on the left rear side of the upper part and on the front side of the lower part. Therefore, the two wires 8 and 10 located on the inner peripheral side (left side) of the optical disc 2 in the tracking direction with respect to the objective lens 13 are arranged in the focus direction.
One wire 8 located on the side (upper side) is offset by a certain distance to the side of the fixing member 74 (rear side) in the tangential direction, and on the opposite side (lower side) in the focusing direction.
The one wire 10 located at is offset to the opposite side (front side) by the same distance in the tangential direction.

The two wires 9 and 11 located on the outer peripheral side (right side) of the optical disk 2 in the tracking direction with respect to the objective lens 13 are arranged in the same manner as the lens driving device 28 described above. Then, the objective lens 13 and the coils 41, 4 of the lens driving mechanism 43 are attached to the lens holder 76.
2 and the light shielding member 45 of the displacement detection sensor 44 are attached to form a movable portion 78 that can be displaced in the focus direction and the tracking direction.

In such a structure, the above-mentioned lens driving device 73 functions similarly to the above-mentioned lens driving device 28 and the like. That is, since the wire 11 on the lower right side is offset rearward, this wire 11 is
Lens holder 76 without interfering with the incident optical path of
Has been made thinner.

Further, since the wire 8 on the upper left side is offset, the wire 8 is prevented from interfering with the turntable 100 as shown in FIG. Therefore, the movable portion 78 can be moved deep inside the optical disc 2, and the inner peripheral portion of the optical disc 2 can be effectively used.

Since the wires 8 and 11 and the wires 9 and 10 are offset in the opposite directions by the same distance,
The moments due to the bending of the wires 8 to 11 are offset, and unnecessary stress does not act on the movable portion 78 to cause resonance.

[0077]

According to the first aspect of the present invention, one elastic support member located on the laser light incident side in the tracking direction with respect to the objective lens and on the reflection mirror side in the focusing direction is arranged in the tangential direction. By offsetting to the fixed member side by a certain distance, this elastic support member can be arranged at a position where it does not interfere with the laser light.
The movable part can be downsized in the focus direction, and the other elastic support member is offset to the opposite side in the tangential direction by the same distance. Since the moments can be canceled out, it is possible to prevent the occurrence of resonance in the movable portion and adverse effects on the optical characteristics of the objective lens.

According to a second aspect of the present invention, one elastic supporting member located on the incident side of the laser beam in the tracking direction with respect to the objective lens and on the reflecting mirror side in the focusing direction is fixed in the tangential direction. By offsetting this side by a certain distance, this elastic support member can be placed in a position where it does not interfere with the laser light, so that the whole can be shortened in the focus direction, and further, in the tracking direction with respect to the objective lens. By offsetting the other elastic support member located on the laser light incident side to the opposite side in the tangential direction by the same distance, the moments of the two offset elastic support members can be offset. Therefore, it is possible to prevent the occurrence of resonance in the movable portion and adverse effects on the optical characteristics of the objective lens.

According to the third aspect of the present invention, the two elastic supporting members located on the incident side of the laser beam in the tracking direction with respect to the objective lens are offset from the fixed member in the tangential direction by the fixed distance. Since this elastic supporting member can be arranged at a position where it does not interfere with the laser light, the whole can be shortened in the focus direction, and further, two elastic members located on the opposite side to the objective lens in the tracking direction can be shortened. By offsetting the support member on the opposite side in the tangential direction by the same distance,
By arranging this elastic support member at a position where it does not interfere with the laser light and offsetting the two elastic support members located on the opposite side in the tracking direction with respect to the objective lens to the opposite side in the tangential direction by the same distance, Since the offset moments of the two elastic support members can be canceled out, it is possible to prevent the occurrence of resonance in the movable portion and adverse effects on the optical characteristics of the objective lens.

According to the fourth aspect of the present invention, the two elastic supporting members located on the reflecting mirror side in the focusing direction with respect to the objective lens are offset by a certain distance to the fixing member side in the tangential direction. Since the elastic supporting member can be arranged at a position where it does not interfere with the laser beam, the whole can be shortened in the focus direction, and further, the two elastic supporting members positioned on the opposite side to the objective lens in the focusing direction. Is offset to the opposite side in the tangential direction by the same distance, so that this elastic support member is placed at a position where it does not interfere with the laser light, and two elastic supports located on the opposite side in the focusing direction with respect to the objective lens. By offsetting the members on the opposite side in the tangential direction by the same distance, the two elastic support member offset Since it is possible to cancel the mentions, it is possible to prevent the occurrence of resonance in the movable portion and adversely affect the optical characteristics of the objective lens, and it is possible to shorten the portion protruding toward the optical disc in the tangential direction. Therefore, it is possible to easily deal with, for example, a disc cassette in which an optical disc is housed in a cassette case having an opening.

According to a fifth aspect of the present invention, one elastic supporting member located on the inner peripheral side of the optical disc in the tracking direction with respect to the objective lens and on the optical disc side in the focusing direction is fixed member side in the tangential direction. Since the elastic support member can be arranged at a position where it does not interfere with the turntable by offsetting it by a certain distance, the objective lens can be moved deep inside the optical disc, and the inner peripheral portion of the optical disc can be moved. It can be effectively used, and offsets the moment of the two offset elastic support members by offsetting the other elastic support member to the opposite side in the tangential direction by the same distance. Therefore, it is possible to prevent the occurrence of resonance in the movable portion and adverse effects on the optical characteristics of the objective lens.

According to the sixth aspect of the present invention, by disposing the lens driving mechanism on both sides of the movable portion in the tangential direction, it is possible to prevent the lens driving mechanism from interfering with the laser beam, and further, to move the movable portion in the tracking direction. Therefore, the objective lens can be easily moved to the vicinity of the center of the optical disc, and the recording surface of the optical disc can be effectively used.

According to a seventh aspect of the present invention, a lens holder is supported by an elastic supporting member, an objective lens is mounted on the lens holder, and a concave portion into which laser light is made incident is formed in the lens holder, and the objective lens is arranged in a tracking direction of the objective lens. By mounting a displacement detection sensor that detects displacement in the vicinity of the recess of the lens holder, the weight reduction of the displacement sensor can be offset by the weight of the recess of the lens holder. Resonance of parts can be prevented.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing a lens driving device according to a first embodiment of the present invention.

2A and 2B show a main part of a lens driving device, FIG. 2A is a plan view, and FIG. 2B is a side view.

FIG. 3 is a perspective view showing a lens driving mechanism.

FIG. 4 is an exploded perspective view showing a displacement detection sensor.

FIG. 5 is a plan view showing a displacement detection sensor.

FIG. 6 is a perspective view showing a main part of a lens driving device according to a second embodiment.

7A and 7B show a main part of a lens driving device, FIG. 7A is a plan view, and FIG. 7B is a side view.

FIG. 8 is a plan view showing a main part of a lens driving device of a modified example.

FIG. 9 is a perspective view showing a main part of a lens driving device according to a third embodiment.

10A and 10B show a main part of a lens driving device, FIG. 10A is a plan view, and FIG. 10B is a side view.

FIG. 11 is a perspective view showing a main part of a lens driving device according to a fourth embodiment.

FIG. 12 is a plan view showing a main part of a lens driving device.

FIG. 13 is an exploded perspective view showing a lens driving device of a first conventional example.

FIG. 14 is an exploded perspective view showing a lens driving device of a second conventional example.

FIG. 15 is a front view showing the positional relationship between the lens driving device and the turntable.

FIG. 16 is a plan view showing a positional relationship between a lens driving device and a turntable.

[Explanation of symbols]

 2 Optical Disc 5 Reflection Mirror 8-11 Elastic Support Member 13 Objective Lens 18 Laser Light 28, 52, 61, 62, 73 Lens Drive Device 32, 53, 60, 63, 74 Fixing Member 35, 56, 66, 76 Lens Holder 38 Recessed portion 43 Lens drive mechanism 44 Displacement detection sensor 51, 59, 69, 78 Movable part

Claims (7)

[Claims] 1. A movable part having an objective lens, in which four or more elastic supporting members elongated in the tangential direction and having the same length are arranged on both sides in the tracking direction and at a plurality of positions in the focusing direction, The movable portion is movably supported in the focus direction and the tracking direction by the other end of the elastic support member whose one end is fixed to a fixed member, the objective lens is opposed to the optical disc, and the movable portion is in the focus direction and the tracking direction. A lens drive mechanism for displacing a laser beam is provided to deflect the laser light incident from the tracking direction in the focusing direction by a reflection mirror, and to make the laser light incident on the objective lens and converge on the track of the optical disc. On the other hand, it is located on the laser light incident side in the tracking direction and The one elastic support member located on the reflection mirror side is offset to the fixed member side in the tangential direction by a certain distance, and the other one elastic support member is oppositely arranged in the tangential direction by the same distance. A lens driving device characterized by being offset. 2. Four elastic support members are arranged on each side of the movable part in the tracking direction, two elastic support members are arranged at two positions in the focusing direction, and two elastic support members are arranged at two positions in the focusing direction. The elastic support member located on the incident side of the laser light and located on the reflection mirror side in the focus direction is offset by a fixed distance to the fixed member side in the tangential direction, and in the tracking direction with respect to the objective lens. 2. The lens driving device according to claim 1, wherein the other one of the elastic supporting members located on the laser light incident side is offset to the opposite side in the tangential direction by the same distance. 3. Four elastic support members are arranged on each side of the movable part in the tracking direction, two elastic support members are arranged at two positions in the focus direction, and two elastic support members are arranged in the tracking direction with respect to the objective lens. The two elastic supporting members located on the laser light incident side are offset to the fixed member side by a fixed distance in the tangential direction, and the two elastic members located on the opposite side in the tracking direction with respect to the objective lens. 2. The lens driving device according to claim 1, wherein the supporting members are offset to the opposite side in the tangential direction by the same distance. 4. The four elastic supporting members are arranged two on each side in the tracking direction with respect to the movable part, and two elastic supporting members are arranged at two positions in the focusing direction, respectively. The two elastic supporting members located on the reflecting mirror side are offset to the fixed member side by a fixed distance in the tangential direction, and the two elastic supporting members located on the opposite side to the objective lens in the focusing direction. 2. The lens driving device according to claim 1, wherein the lenses are offset by the same distance on the opposite side in the tangential direction. 5. An elastic supporting member located on the inner peripheral side of the optical disc in the tracking direction with respect to the objective lens and on the optical disc side in the focusing direction is offset by a fixed distance in the tangential direction to the fixed member side. The lens driving device according to claim 1, wherein the other elastic support member is offset to the opposite side in the tangential direction by the same distance. 6. The lens driving mechanism is arranged on both sides of the movable portion in the tangential direction.
The lens driving device according to 2, 3, 4 or 5. 7. A lens holder is supported by an elastic support member,
An objective lens is attached to this lens holder, a concave portion where laser light is incident is formed on the lens holder, and a displacement detection sensor for detecting displacement of the objective lens in the tracking direction is attached near the concave portion of the lens holder. The lens driving device according to claim 1, 2, 3, 4, or 5.