JPS62226434A - Optical system driving device - Google Patents

Abstract

PURPOSE:To attain an excellent action without resonance at the time of driving an optical system by providing two supporting means capable of moving a holding member in different directions and linking two bearing holding members comprising the link mechanism of the 1st supporting means through an elastic member. CONSTITUTION:When a current is caused to flow in a coil 88, the interaction between magnetic fields generated by permanent magnets 54a and 54b vertically oscillates a part consisting of pivot spindles 74a, 74b, 74c and 74d, pivot bearings 78a and 78b, an objective lens holding body 76, an objective lens 80, and coils 86 and 88 through wires 72a, 72b, 72c and 72d due to a turn around the spindles 70a and 70b, thereby executing auto focusing. In accordance with a current flowing in the coil 88 the objective lens holding body 76 moves upward, and each wire tilts from a horizontal level. The upper end of the objective lens holding body 76 is positioned a distance L2 from a recording medium 90, and a neutral position holding elastic body 92 is deformed due to the move of the objective lens holding body 76. Thus a parallel link mechanism can prevent the optical axis of the objective lens 80 from falling, thereby executing the auto focusing.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical system driving device, and particularly to a device capable of driving an optical system two-dimensionally. Such an optical system drive device is suitably used, for example, to drive an objective lens of an optical head in an optical information recording/reproducing device.

[Conventional technology and its problems]

Conventionally, optical information recording and reproducing devices have been put into practical use, which record information on a recording medium and/or reproduce information recorded on the recording medium while irradiating the surface of the information recording medium with a spot of laser light. has been made into

An example of such a device is an optical disk device. An optical disk, which is a recording medium on which information is reproduced by an optical disk device, has an information track formed in a helical shape or concentric circle shape, which is made up of a row of information pits with a width of about 1 to 2 μm and a length of about 1 to 3 μm. When reproducing the information recorded as the information focus row, without rotating the optical disk, a laser beam is irradiated from the optical disk in a microscopic shape onto the information trunk of the optical disk, and the information is focused by the beam spot. Scan the columns. When a photodetector detects the reflected or transmitted light of the light irradiated onto the optical disk surface in this way, the optical difference of the light incident on the photodetector depends on whether or not there is an information focus at the beam spot position. Character changes. In this way, a reproduced signal corresponding to the information pit string can be obtained.

One of the features of optical discs is that they are capable of high-density recording, so the information pits are quite small as mentioned above.
For this reason, in optical disk devices, in order to reproduce accurate information, it is necessary for the light beam spot to always accurately follow the information track (tracking) and for the light beam spot to always be focused on the information track (focusing). be.

For this reason, optical disk devices generally perform auto-tracking control to correct optical beam spot position deviations caused by eccentricity of the optical disk, and autofocusing control to correct out-of-focus deviations caused by warping of the optical disk.

As a method for realizing such auto-tracking control and auto-focusing control, the objective lens, which is the optical beam focusing means of the optical head, is movable in the direction of the optical axis of the lens and in the direction orthogonal thereto using a spring-like structure. A method is generally used in which the objective lens is driven so as to eliminate the positional deviation and defocusing of the light beam spot based on detection signals of the positional deviation and defocusing of the light beam spot.

FIG. 8 is a perspective view showing a conventional objective lens driving device for an optical head having means for such auto-tracking control and auto-focusing control.

In FIG. 8, 2 is a base, and a yoke 6 to which a permanent magnet 4 is attached is fixed on the base. One end of a pair of leaf springs 8ay8b, each located in a vertical plane, is fixed to the yoke, and the opposing vertical end surface of a square relay plate 10 is fixed to the other end of the leaf spring. One end of a pair of temporary springs 12a and 12b each located in a horizontal plane is also fixed to the opposing horizontal end surfaces of the relay plate 10, and an objective lens holder 14 is fixed to the other end of the temporary spring. ing. 16 is an objective lens held by the holder. On the other hand, a yoke 20 to which a permanent magnet 18 is attached is fixed to the base 2.

A coil 22 wound horizontally is attached to the objective lens holder 14 on the side of the permanent magnet 4, and the coil 22 is arranged so as to surround a part of the yoke 6.

A coil 24 wound vertically is attached to the permanent magnet 18 side of the objective lens holder I4.
The coil is arranged to surround a part of the yoke 20.

Note that the base 2 is provided with a through hole 26 below the objective lens 16, thereby ensuring an optical path for the light beam passing through the objective lens 16.

In the objective lens drive device as described above, the relay plate 10
, a portion consisting of the temporary springs 12a, 12b, the objective lens holder 14, the objective lens 16, and the coil 22°24 is horizontally swingable with respect to the yoke 6 via the plate springs 8a, 8b. This realizes horizontal movement of the objective lens 16 (ie, movement for auto-tracking control). This movement is driven by the interaction with the magnetic field of the permanent magnet 4 by passing a current through the coil 22.

Further, a portion consisting of the objective lens holder 14, the objective lens 16, and the coils 22 and 24 is a plate spring 12a.

12b in a direction perpendicular to the relay plate 10.
This allows vertical movement of the objective lens 1G (ie, movement for autofocusing control). This movement is driven by the interaction with the magnetic field of the permanent magnet 18 by passing a current through the coil 24.

However, in the conventional objective lens driving device as described above, since the movable part is supported in two stages by plate springs, the optical axis of the objective lens may be tilted due to twisting of the plate springs. There has been a problem in that resonance occurs with high-frequency drive signals, resulting in unstable operation.

[Background of the invention]

As a solution to the problems of the conventional objective lens drive device as described above, an objective lens drive device as shown in FIG. 9 can be considered.

In FIG. 9, reference numerals 52a and 52b are a pair of bases disposed facing each other, a permanent magnet 54a is disposed on the base 52b side of the base 52a, and the base 52a of the base 52b is
A permanent magnet 54b is arranged on the side. Also, the base 5
A pair of yokes 56 are arranged between the permanent magnets 2a and 52b so as to sandwich the permanent magnets 54a and 54b from above and below.
a.

56b is arranged, and the base 52a,
52b are connected. A through hole 57 is provided in the yoke 56a.
A through hole 56b is also provided below the through hole 57a.

A pivot bearing holder 58 is fixed to the upper part of the base 52a. A pair of pivot bearings (only the upper bearing 60a is shown) are attached to the pot bearing holder, and a pivot shaft (not shown) is disposed between them. The pivot axis is arranged vertically and a bearing holder 66 is coupled to the pivot axis. Two bearings 68a and 68b are fixed to the bearing holder 66, and the bearings are arranged parallel to each other and horizontally. Shafts 70a and 70b are rotatably coupled to the bearings, respectively. An equivalent wire 72a having appropriate rigidity is provided at both ends of the shaft.

One ends of 72b, 72c, and 72d (not shown) are fixed. A pivot shaft 74a is attached to the other end of the wire 72a.
One end of the wires 72b and 72c is fixed, and similarly the wires 72b and 72c
, 72. Pivot shafts 74b and 74 are provided at the other end of d, respectively.
c, one end of 74d (not shown) is fixed. The pivot shafts 74a and 74C are arranged coaxially,
An objective lens holder 7 is placed between these opposing pivot ends.
A pivot bearing 78a fixed to 6 is clamped.

Similarly, the pivot axes 74b and 14d are arranged coaxially, and an in-vivo bearing is fixed to the objective lens holder 76 between these opposing pivot ends. 8b is being held. 80 is an objective lens held by the objective lens holder 76.

A column 84 to which permanent magnets 82a and 82b are attached is fixed to the upper part of the base 52b. A flat coil 86 wound horizontally is attached to the surface of the objective lens holder 76 facing the permanent magnets 82a, 82b. Further, a coil 88 is attached to the lower part of the objective lens holder 76 and is disposed through the through hole 57a of the yoke 56a.

In the objective lens drive device as described above, the coil 86
By passing a current through the permanent magnet 82a.

Due to the interaction with the magnetic field generated by 82b, the portion of the arm 64 extending from the bearing holder 66 to the objective lens holder 76 horizontally rotates around a pivot shaft fixed to one end of the arm 64. Auto tracking is thereby performed.

In addition, by passing current through the coil 88, the permanent magnet 54
The interaction with the magnetic field caused by a, 54b causes the biological axis 74 to
a, 74b, 74c, 74d, pivot bearing 78a, 7
8b, the portion consisting of the objective lens holder 76, the objective lens 80, and the coils 86 and 88 is the wire 72a, 72b,
Via 72c, 72d, their axes 70a, 70b
Rotation around the lens causes it to swing vertically, thereby performing autofocusing.

Since such an objective lens driving device does not use a springy member for movement, it is possible to solve the above-mentioned problems of the conventional device as shown in FIG. 8 above. However, in the objective lens drive device as shown in FIG. 9, a parallel link mechanism is used as a means for vertically movably supporting the objective lens 80.
When the objective lens holder 7 is not in operation, as shown in FIG.
6 is lowered by its own weight until it touches the yoke 56a, and the distance L3 between the upper end of the objective lens holder and the recording medium 90 becomes considerably large (that is, the objective lens 80 is far away from the neutral position in the focusing movement direction). For this reason,
It is difficult to focus quickly when starting autofocusing control.

Therefore, the present invention solves both the problems of the conventional drive device as shown in FIG. 8 above and the problem of the drive device as shown in FIG. 9 above, and achieves good operation. Another object of the present invention is to provide a quick optical system driving device.

[Summary of the invention]

According to the present invention, the above objects include an optical system, a means for holding the optical system, and a first support means including a link mechanism for movably supporting the optical system holding means in a first direction. and a second support means connected to the first support means and supporting the optical system holding means movably in a second direction different from the first direction, the first support means This is achieved by an optical system driving device characterized in that two bearing holding members constituting a link mechanism are connected via an elastic member.

〔Example〕

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view showing an embodiment of the optical system driving device of the present invention, and FIG. 2 is a partially sectional side view thereof. This embodiment is applied to driving an objective lens of an optical information recording/reproducing device.

In these figures, 52a and 52b are a pair of bases arranged opposite to each other, a permanent magnet 54a is arranged on the side of the base 52b of the base 52a, and a permanent magnet 54a is arranged on the side of the base 52b of the base 52b.
A permanent magnet 54b is arranged on the 2a side. Further, the permanent magnets 54a and 54 are placed between the bases 52a and 52b.
A pair of yokes 56a are arranged so as to sandwich b from above and below.

56b is arranged, and the base 52a,
52b are connected. A through hole 57 is provided in the yoke 56a.
A through hole 57b is provided in the yoke 56b below the through hole 57a. Also,
The yoke 56b has a cylindrical portion 57c extending upwardly around the through hole 57b.

A pivot bearing holder 58 is fixed to the upper part of the base 52a. FIG. 3 shows a longitudinal sectional view of the vicinity of the pivot bearing holder 58. A pair of pivot bearings 60a, 60b are attached to the pivot bearing holder, and a pivot shaft 62 is disposed between them. The pivot shaft is arranged vertically, and a bearing holder 6 is attached to the pivot shaft.
6 are combined.

As shown in FIGS. 1 and 2, two bearings 68a and 68b are fixed to the bearing holder 66, and the bearings are arranged parallel to each other and horizontally. Shafts 70a and 70b are rotatably coupled to the bearings, respectively. Equivalent wires 72a having appropriate rigidity are provided at both ends of the shaft.

One ends of 72b, 72c, and 72d (not shown) are fixed. A pivot shaft 74a is attached to the other end of the wire 72a.
One end of the wires 72b and 72c is fixed, and similarly the wires 72b and 72c
, 72d have pivot shafts 74b, 74c, respectively.
, 74d (not shown) are fixed at one end. The pivots H*74a and 74c are arranged coaxially, and the objective lens holder 7 is placed between these opposing pivot ends.
A pivot bearing 78a fixed to 6 is clamped.

Similarly, the pivot I/shafts 7' 4b and 74d are arranged coaxially, and a pivot bearing 78b fixed to the objective lens holder 76 is sandwiched between these opposing pivot ends. FIG. 4 is a cross-sectional view showing the coupling relationship between the pivot shaft and the pivot bearing.

In FIGS. 1 and 2, wire 72a.

? 2b, 72c, and 72d all extend in the horizontal direction, wires 72a and 72c are arranged at the same height, wire 72b and wire 72d are arranged at the same height, and the wires 72a and 72c are arranged at the same height. Is 72b a wire? Wire 72d is located below wire 72c. Therefore, the pivot axes 74a, 74b, 74c, 74d
are arranged parallel to the axes 70a and 70b and coaxially or parallel to each other, and the pivot axis 74b
4a, and the pivot shaft 74d is located below the pivot shaft 7.
It is located below 4c. The pivot bearings 78a and 78b are arranged horizontally and parallel to each other, and the pivot bearing 78b is located below the pivot bearing 78a. 80
is an objective lens held by an objective lens holder 76.

In FIGS. 1 and 2, a column 84 to which permanent magnets 82a and 82b are attached is fixed to the upper part of the base 52b. The permanent magnet 82a of the objective lens holder 76
, 82b is provided with a flat coil 86 wound horizontally. Further, in the lower part of the objective lens holder 76, a through hole 57 of the yoke 56a is provided.
A coil 88 is attached to the outside of the cylindrical portion 57c of the yoke 56b so as to extend coaxially through the yoke 56b.

Note that the through hole 57a provided in the yoke 56a and the yoke 5
An optical path for the light beam passing through the objective lens 80 is secured by the through hole 57b and the cylindrical portion 57c provided in the objective lens 80. Further, in FIG. 2, 90 is an information recording medium.

FIGS. 5(a) and 5(b) are partial plan views showing one step of assembling the apparatus of this embodiment. First, as shown in FIG. 5(a), four wires 72a, 72b, and 72c are connected.

72d is horizontally bent outward by applying an external force to move the pivot shafts 74a, 74b, 74c, and 74d outward, and the objective lens holder 76 is placed at a predetermined position. Next, the wire 72a.

By releasing the external force applied to 72b, 72c, and 72d, the pivot shaft 74 is moved as shown in FIG. 5(b).
a, 74b, 74c, and 74d respectively as pivot bearings 7
It is connected to both ends of 8a and 78b.

As can be seen from the above description, the wires 72a and 72b.

? 2c and 72d have such characteristics that they are elastically deformed by an appropriate external force during assembly, and can be regarded as substantially rigid bodies when the objective lens is driven.

As can be seen from the above description, the device of this embodiment includes a bearing holder 66, bearings 68a, 68b, and shafts 70a, 70.
b, and wires 72a, 72b.

72c, 72d and pivot bearings 74a, 74b.

74c, 74d, pivot bearings 78a, 78b, and objective lens holder 76 constitute a parallel link mechanism.

Furthermore, in the apparatus of this embodiment, as shown in FIG. 2, the bearing holder 66 and the objective lens holder 76 are connected by a neutral position holding elastic body 92 made of rubber.

In the device of this embodiment as described above, the permanent magnet 82a is generated by passing a current through the coil 86.

82b, the bearing holder 66, bearings 68a, 68b, shafts 70a, 70b, wires 72a, 7
2b, 72c, 72d, pivot shafts 74a, 74b, 7
4c, 74d, pivot bearings 78a, 78b, objective lens holder 76, objective lens 80, and coils 86, 88
, and the neutral position holding elastic body 92 rotate in the horizontal direction around the pivot shaft 62, thereby performing auto-tracking. FIGS. 6(a) and 6(b) are plan views for explaining the operation during auto-tracking. FIG. 6(a) shows a state in which the objective lens 80 is in a neutral position with respect to the tracking movement direction, and FIG. 6(b)
) is the objective lens 80 depending on the current flowing through the coil 86.
This is a state in which the movable parts including the movable parts have been rotated by an angle θ around the pivot shaft 62 from the state shown in FIG. 6(a). The angle θ can be changed by changing the magnitude of the current flowing through the coil 86, and thus the objective lens 80 can be moved in the horizontal direction.

In addition, in the device of this embodiment, when a current is passed through the coil 88, the pivot shafts 74a, 74b are fixed by interaction with the magnetic field generated by the permanent magnets 54a, 54b.

74c, 74d, pivot bearings 78a, 78b, objective lens holder 76, objective lens 80, and coil 86.8
The part consisting of 8 is the wire 72a.

Via 72b, 72c, 72d, their axes 70a,
Rotation around 70b causes the lens to swing vertically, thereby performing autofocusing. FIG. 7 is a partially sectional side view for explaining the autofocusing operation, showing the same portion as FIG. 2. FIG. FIG. 2 shows a state in which no current is flowing through the coil 88, and the wire 72
a.

72b (also 72C, 72d) is horizontal, and the upper end of the objective lens holder 76 is located at a distance L1 from the recording medium 90. That is, in this embodiment, the neutral position holding elastic body 9 is installed so that the objective lens 80 is at a neutral position with respect to the forcing movement direction when no current flows through the coil 88.
2, the objective lens holder 76 is connected to the bearing holder 66.

Therefore, it goes without saying that the distance L1 is smaller than the distance L3 in FIG. 10 above. FIG. 7 shows a state in which the objective lens holder 76 has moved upward in response to the current flowing through the coil 88, each wire is tilted from the horizontal, and the upper end of the objective lens holder 76 is at a distance L2 from the recording medium 90. in position. Further, the neutral position holding elastic body 92 is deformed as the objective lens holder 76 moves.

In this way, autofocusing can be quickly performed by the parallel link mechanism without causing the optical axis of the objective lens 80 to tilt.

Since the auto-tracking drive and auto-focusing drive described above are not performed via a spring member, resonance does not occur even with high-frequency drive.

In the apparatus of this embodiment, the objective lens 80 is located closer to the bearing holder 66 than the pivot bearings 78a, 78b, so the apparatus can be made more compact than in the opposite case. Furthermore, in the device of this embodiment, since the set of pivot bearings 60a, 60b and pivot shaft 62 are directly coupled to the bearing holder 66, the distance from the end of the base 52a to the end of the base 52b is The device length 12 of can be relatively short.

In addition, in the apparatus of this embodiment, - objective lens holder 7
6 is supported via pivot bearings 78a and 78b, the objective lens holder 7 is supported during autofocusing.
6 does not wobble horizontally.

In the above embodiment, a parallel link mechanism is used as the link mechanism associated with the first support means, but in the present invention, a link mechanism other than the parallel link mechanism can also be used as the link mechanism.

Further, although the above embodiment is applied to driving an objective lens of an optical information recording/reproducing apparatus, the present invention can be applied to driving other appropriate optical systems. The optical system to be driven is not limited to a lens or a lens system, but may be a mirror, a prism, or a composite optical system including these.

〔Effect of the invention〕

According to the present invention as described above, resonance does not occur when the optical system is driven, and the operation is performed smoothly and quickly.

[Brief explanation of drawings]

1, 8, and 9 are perspective views of the optical system driving device. FIG. 2, FIG. 7, and FIG. 10 are partially sectional side views of the optical system driving device. FIG. 3 is a longitudinal sectional view of the pivot bearing holder. FIG. 4 is a cross-sectional view of the objective lens holder. FIGS. 5(a) and 5(b) are diagrams showing one step of assembling the optical system drive device. FIGS. 6(a) and 6(b) are plan views of the optical system driving device. 52a, 52b: base, 54a, 54b, 82a. 82b; Permanent magnet, 56a, 56b: Yoke, 58: Pivot bearing holder, 60a, 60b. 78a, 78b: Pivot bearing, 62.74a. 74b, 74c, 74d: Pivot shaft, 66: Bearing holder, 68a, 68b: Bearing, 70a, 70b: Shaft, ? 2
a, 72b, 72c, 72d: wire, 76: objective lens holder, 80: objective lens, 86.88: coil, 9
2: Neutral position holding elastic body. Agent Patent Attorney Jo Taira Yamashita Figure 1 Figure 2 Figure 3 Figure 4 Figure 2Q Figure 6 (G) Figure 6 (b) Figure 7 jn? Figure 10 57b 57c

Claims (3)

[Claims] (1) an optical system, a means for holding the optical system, a first support means including a link mechanism that supports the optical system holding means movably in a first direction; and a second support means that is connected and supports the optical system holding means so as to be movable in a second direction different from the first direction, and two bearings that constitute a link mechanism of the first support means. An optical system driving device characterized in that holding members are connected via an elastic member. (2) The optical system drive device according to claim 1, wherein the link mechanism is a parallel link mechanism. (3) The optical system drive device of claim 1, wherein the second support means includes a pivot bearing. (4) The optical system according to claim 3, wherein the pivot bearing of the second support means is directly coupled to one of the bearing holding members constituting the link mechanism of the first support means. Drive device.