JPS62226435A - Optical system driving device - Google Patents

Abstract

PURPOSE:To excellently an optical system without causing resonance when it is driven by providing two supporting means which movably support an optical system holding means in different directions and directly connecting the pivot bearing of the second supporting means to one of bearing of the second supporting means to one of bearing holding members which constitute the link mechanism of the first supporting means. CONSTITUTION:When an electric current is conducted in a coil 88, the interaction of magnetic fields made by permanent magnets 54a and 54b vertically rocks a part consisting of pivot shafts 74a, 74b, 74c and 74d, pivot bearings 78a and 78b, an objective lens holding body 76, an objective lens 80, coils 86 and 88 through wires 72a, 72b, 72c and 72d by the turn around shafts 70a and 70b and autofocusing is executed. In response to the current conducting in the coil 88, the objective lens holding body 76 shifts upwards and respective wires tilt from the horizontal level. The upper end of the objective lens holding body 76 is positioned at a distance L2 from a recording medium 90. Thus, a parallel link mechanism causing the optical shaft of the objective lens 80 from falling, whereby the lens focuses automatically.

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 a width of about 1 to 2 μm and a length of 1 to 3 μm.
An information track consisting of a row of information pits is formed in a spiral shape or a concentric circle shape. When reproducing the information recorded as the information pit string, without rotating the optical disk, a laser beam is irradiated from the optical head in the form of a minute spot onto the information trunk of the optical disk, and the information bit string is scanned by the beam spot. . When a photodetector detects the reflected light 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 pit at the beam spot position. Character changes. In this way, a reproduced signal corresponding to the information pin/node sequence can be obtained.

One of the features of optical discs is that they are capable of high-density recording, and therefore the information field is quite small as mentioned above.For this reason, in optical disc devices, a light beam spot is used for accurate information reproduction. It is necessary for the light beam spot to always accurately follow the information track (track tracking) and for the light beam spot to always be focused on the information track (focusing).

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

As a method for realizing such auto-tracking control and auto-focusing control, an objective lens, which is a light beam focusing means, is movable in the optical axis direction of the lens and in a direction perpendicular thereto using a spring-like structure. Generally, a method is 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 temporary springs 8a and 8b, 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 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 14.
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. Accordingly, horizontal movement of the objective lens 16 (ie, movement for auto-trunking control) is realized. 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.

The objective lens 16 can be oscillated in the vertical direction with respect to the relay plate 10 via the relay plate 12b, thereby realizing vertical movement of the objective lens 16 (that is, 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] An objective lens drive device as shown in FIG. 9 can be considered as a solution to the problems of the conventional objective lens drive device as described above.

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 pivot bearing holder, and a pivot shaft (not shown) is disposed between them. The pivot axis is arranged vertically, and one end of a horizontally extending arm 64 is fixed to the center of the pivot axis.

A bearing holder 66 is coupled to the other end of the arm 64. The bearing holder 66 has two bearings 68a.

G8b is fixed and the bearings are arranged parallel to each other and horizontally. The bearings have shafts 70a and 7, respectively.
0b is rotatably coupled.

One ends of equivalent wires 72a, 72b, 72c, and 72d (not shown) having appropriate rigidity are fixed to both ends of the shaft. One end of a pivot shaft 74a is fixed to the other end of the wire 72a.
A pivot shaft 74 is provided at the other end of b, 72c, and 72d, respectively.
b, 74c, and 74d (not shown) are fixed at one end. The pivot shafts 74a and 74c are arranged coaxially, and a pivot bearing 78a fixed to the objective lens holder 76 is sandwiched between these opposing pivot ends. Similarly, the pivot shafts 74b and 74d are arranged coaxially, and a pivot bearing 78b fixed to the objective lens holder 76 is sandwiched between these opposing pivot ends. 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 from the arm 64 to the bearing holder 66 and the objective lens holder 76 horizontally rotates around a pivot shaft fixed to one end of the arm 64. Auto tracking is performed.

In addition, by passing current through the coil 88, the permanent magnet 54
The pivot axis 74a due to the interaction with the magnetic field caused by a and 54b.
, 74b, 74c, 74d, pivot bearings 78a, 78
b. Is the portion consisting of the objective lens holder 76, objective lens 80, and coils 86 and 88 wire? 2a, 72b,?
2c and 72d, by rotation around the axes 70a and 70b, it swings up and down, thereby performing autofocusing.

Since such an objective lens driving device does not use a spring member for movement, it is possible to solve the above-mentioned problems of the conventional device shown in FIG. 8 above.

However, in the objective lens drive device as shown in FIG. The device length II from the end of the stand 52a to the end of the base 52b is relatively long, and there is a limit to miniaturization of the device.

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 an optical system driving device that can be downsized.

[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 including a pivot bearing coupled to the first support means and movably supporting the optical system holding means in a second direction different from the first direction, This is achieved by an optical system driving device characterized in that 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. .

〔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 disposed, and the yoke supports the base 52a.
, 52b are connected. The yoke 56a has a through hole 5.
A through hole 57b is also provided in the yoke 56b below the through hole 57a. Further, the yoke 56b has a cylindrical portion 57C extending upward 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 7) 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.
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. ing. 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. The wire? A pivot shaft 74a is provided at the other end of 2a.
One end of the wires 72b and 72c is fixed, and similarly the wires 72b and 72c
, '72d have pivot shafts 74b, 74 at the other ends, respectively.
c, one end of 74d (not shown) is fixed. The pivot shafts 74a and 74C are arranged coaxially, and a pivot bearing 78a fixed to the objective lens holder 76 is sandwiched between these opposing pivot ends.

Similarly, the pivot shafts 74b 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.

72 b, 72 c, and 72 d all extend horizontally, wires 72 a and 72 C are placed at the same height, and wires 72 b and 72 d are placed at the same height. , and is the wire 72b a wire? The wire 72d is located below the wire 72C. Therefore, the pivot axes 74a, 74b,
74c and 74d are arranged parallel to the axes 7Qa and 7Qb and coaxially or parallel to each other, and the pivot shaft 7
4b is located below the pivot shaft 74a, and the pivot shaft 74b is located below the pivot shaft 74a.
4d is located below the pivot shaft 74C. 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 the 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.

72c 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 7Qa, 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.

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
rotates in the horizontal direction around the pivot shaft 62, thereby performing auto-tracking. 6th
Figures (a) and (b) are plan views for explaining the operation during auto-tracking. FIG. 6(a) shows a state in which the objective lens 80 is at a neutral position with respect to the tracking movement direction, and FIG. 6(b) shows a state in which the movable portion including the objective lens 80 is moved to the sixth position according to the current flowing through the coil 86. figure(
This is a state in which the state has been rotated by an angle θ around the pivot shaft 62 from the state in a). The angle θ can be changed depending on the magnitude of the current flowing through the coil 86, and thus the objective lens 8
0 can be moved horizontally.

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.

? 4C, 74d, vivo throat bearings 78a, 78b, objective lens holder 76, objective lens 80, and coil 86.
The portion consisting of 88 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. 2 shows a state in which the objective lens 80 is in a neutral position with respect to the focusing movement direction, and the wires 72 a, 72 b (
72c.

72d) is also horizontal, and the upper end of the objective lens holder 76 is located at a distance from the recording medium 90.

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 from the recording medium 9°0. It is located at L2 position.

In this way, autofocusing is 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 due to high-frequency drive.

In the device of this embodiment, the objective lens 80 is mounted on the pivot bearing 7.
Since it is located closer to the bearing holder 66 than 8a and 78b, the device 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 connected 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. That is, compared to the length 21 in the apparatus shown in FIG. 9, 22<1! ,
It is.

In addition, in the apparatus of this embodiment, the objective lens holder 76
Since the objective lens holder 76 is supported via pivot bearings 78a and 78b, the objective lens holder 76 is
There is no wobbling in the horizontal direction.

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, the optical system can be operated satisfactorily and accurately without causing resonance when driving the optical system, and the apparatus can be miniaturized.

[Brief explanation of drawings]

1, 8, and 9 are perspective views of the optical system driving device. 2 and 7 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, 82
a. 82b: Permanent magnet, 56a, 56b: Yoke, 58: Pivot bearing holder, 60a, 60b. 78a, 73b: Pipod bearing, 62, 74a. 74b, 74C, 14d: Pivot shaft, 66: Bearing holder, 68a, 68b: Bearing, 70a, 70b: Shaft, 72
a, 72b, 72c, 72d: wire, 76: objective lens holder, 80: objective lens, 86.88: coil. Agent Patent Attorney Minoru Yamashita Child Nae 1 Figure 2 Figure 1O57c Figure 3 Figure 4 Figure 5 Cause (0) Figure 6 (G) Figure 6 (b) Figure 7 Figure 8 Figure 9

Claims (2)

[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 including a pivot bearing connected to the optical system holding means so as to be movable in a second direction different from the first direction, the pivot bearing of the second support means being connected to the optical system holding means in a second direction different from the first direction. An optical system driving device, characterized in that the optical system driving device is directly coupled to one of the bearing holding members constituting the link mechanism of the first supporting means. (2) The optical system drive device according to claim 1, wherein the link mechanism is a parallel link mechanism.