JPH0522976B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a device for supporting an optical system so that it can be driven two-dimensionally. Such an optical system support device is suitably used, for example, to support an objective lens of an optical information recording and reproducing apparatus that records and reproduces information on a recording medium using optical means.

[Prior Art] In an optical information recording/reproducing apparatus, a laser beam is focused by an objective lens to form a minute spot on an information track, and the information track is scanned using the spot. In order to perform recording and reproduction accurately, it is necessary that the minute spot always follow the information track in a sufficiently focused state. Therefore, in optical information recording and reproducing devices, the focusing state on the recording medium and the tracking state on the information track are constantly detected, and when these are about to deviate from the appropriate range, the objective lens is adjusted. Control is performed to maintain proper focusing and tracking states by moving the lens. Such focusing control and tracking control is achieved by supporting an objective lens movably in two dimensions, and fixing a focusing control coil and a tracking control coil directly or indirectly to the objective lens. Further, each of the coils is placed in an appropriate steady magnetic field, and the amount of current applied to each of the coils is controlled in accordance with the detection signals of the focusing state and tracking state.

Conventionally, as an objective lens support device in such an optical information recording/reproducing apparatus as described above, a device in which two sets of parallel plate springs are connected in series so as to be perpendicular to each other has been used. In this device, the deflection of one set of parallel plate springs causes the objective lens to move in the focusing direction, and the deflection of the other set of parallel plate springs causes the objective lens to move in the tracking direction.

However, in such an objective lens support device, for example, when one set of parallel plate springs is deflected for focusing control, stress is generated in the same direction in the other set of parallel plate springs. However, there was a problem in that unnecessary resonance occurred, making accurate control difficult. Another problem was that the structure was complicated and the assembly cost was high.

Therefore, in order to solve the above-mentioned difficulties with the objective lens support device using parallel plate springs, an objective lens support device that supports the objective lens using four mutually parallel metal wires has been proposed in recent years ( (Japanese Patent Application Laid-Open No. 59-221839). FIG. 6 is a perspective view showing a schematic configuration of an objective lens support device using this method. In the figure, 52 is an objective lens having an optical axis in the Z direction, and 54 is a holding member for the objective lens. On the other hand, 56 is a fixing member for supporting and fixing the movable part including the objective lens. Reference numeral 58 denotes a support member made of metal wire, all four of which have the same properties, and one end of each is attached to the holding member 5.
4, and the other end is fixed to a fixing member 56. The support members 58 made of these four metal wires are arranged parallel to each other and at four ridgeline positions of a rectangular parallelepiped. Further, the support members made of these metal wires have appropriate bending elasticity.
Thus, in this objective lens support device,
The holding member 54 can reciprocate over an appropriate range in the Z direction (focusing direction) and the X direction (tracking direction).

[Problems to be Solved by the Invention] However, in the objective lens support device as shown in FIG. 6, the rigidity against torsion around the Y direction is low. When the point of application of the driving force on the movable part during driving or tracking control driving does not match in the Z direction and the X direction, torsional vibration around the Y axis 60
There is a problem in that it is easy to occur.

FIGS. 7 and 8 are schematic diagrams for explaining the occurrence of such torsional vibration. That is, for example, in FIG. 7, a force 62 in the X direction is applied to the tip of the metal wire 58 (i.e., the fixed end to the objective lens holding member 54).
If this occurs, all the metal wires 58 will be easily bent in that direction. Therefore, as shown in FIG. 8, when forces in opposite directions are easily applied to the tips of two pairs of metal wires 58, each pair of metal wires 58
8 are bent in the directions of arrows 64 and 66, respectively, and thus the objective lens holding member 54, which is a rigid body fixed to the tip of the metal wire 58, is easily rotated in the direction of arrow 68 around the Y direction. .
Then, due to the elastic energy stored as the metal wire 58 is bent due to this rotation, the objective lens holding member 54 starts to rotate in the direction opposite to the direction of the arrow 68, and this process is repeated thereafter, resulting in torsional vibration.

Furthermore, a device similar to the objective lens support device shown in FIG. 6 is disclosed in Japanese Patent Application Laid-open No. 121545/1983. In this device, when an optical system is supported by four elongated support members, the support members are arranged in a substantially V-shape when viewed from the optical axis direction of the optical system.

However, in this device, elastic deformation of the support member is used only to move the optical system in the focusing direction, and other means are used to move the optical system in the tracking direction, so the overall configuration is relatively complicated. be.

In addition, in a support device arranged in this way, if we try to utilize the elastic deformation of the support member to move the optical system in the tracking direction, since the positions of the pair of support members fixed to the fixed member are the same,
The support member was difficult to deform and required a large driving force to move in the tracking direction.

[Means for Solving the Problems] According to the present invention, in order to solve the problems of the prior art as described above, the optical system is supported so as to be movable independently in two directions substantially perpendicular to each other. An optical system support device includes a member for holding an optical system, a fixing member, and a plurality of rod-shaped support members having one end fixed to the optical system holding member and the other end fixed to the fixing member and having bending elasticity. The supporting members are arranged in a plane substantially perpendicular to one of the two moving directions of the optical system, and are arranged so as to intersect with each other between both ends when viewed from the one moving direction. There is provided an optical system support device characterized in that at least two sets of the optical system support device are arranged in parallel with respect to the one movement direction.

[Example] Hereinafter, specific examples of the present invention will be described with reference to the drawings.

FIG. 1 is an exploded perspective view showing an embodiment of an optical system support device according to the present invention, and FIG. 2 is a cross-sectional view of the optical system support device in an assembled state. Note that this embodiment shows an example in which the present invention is applied to supporting an objective lens of an optical information recording/reproducing device.

In FIGS. 1 and 2, reference numeral 2 denotes a board fixed to the main body of the apparatus, and the board is made of a ferromagnetic material such as electromagnetic soft iron. A through hole 4 is provided approximately in the center of the substrate 2 to ensure a vertical optical path.
is provided. A cylindrical member 6 that can protrude upward is fixed around the through hole of the substrate 2. Moreover, on the substrate 2, there are two parts around the cylindrical member.
Book permanent magnets 8 and 10 are bonded together, and a flat plate member 12 is bonded and fixed onto the two permanent magnets. The cylindrical member 6 of the flat plate member
A circular opening 14, which is somewhat larger than the outer shape of the cylindrical member, is formed in a portion corresponding to the cylindrical member.
Note that the cylindrical member 6 and the flat member 12 are connected to the substrate 2.
Both act as yokes for the magnetic circuit formed by permanent magnets 8 and 10.

An upright flat plate member 16 is also fixed with screws on the substrate 2, and on one side of the upright flat plate member, two permanent magnets 18 and 20 are arranged parallel to each other and facing in the vertical direction and separated by a predetermined distance. It is fixed with adhesive so that it will look like this.

A fixing member 22 for supporting and fixing the objective lens is also fixed on the substrate 2 by screws.
Four equivalent wires 24a, 24 each existing in a plane parallel to the X-Y plane are provided on the side surface of the fixing member.
b, 26a, 26b are fixed at one end.
Incidentally, each of the wires is insulated and coated with rubber, resin, or the like. As shown, wire 24a
and 24b are arranged so as to intersect with each other when viewed from the Z direction, and are located at slightly different positions in the Z direction (that is, they are slightly separated in the vertical direction). Wires 24a and 24b are equivalent;
In particular, the length and bending elasticity are substantially the same. Further, the wires 24a and 24b are arranged symmetrically so as to intersect each other at approximately right angles at the center when viewed from the Z direction. The relationship between the wires 26a and 26b is also the same as the relationship between the wires 24a and 24b, and the wires 26a and 26b have the same arrangement as the wires 24a and 24b when viewed from the Z direction.

An objective lens holding member 28 is fixed to the other ends of the wires 24a, 24b, 26a, and 26b, and thus the wires have the role of an objective lens supporting member. An objective lens 30 having an optical axis in the Z direction is fixedly held on the holding member, and the objective lens is located above the through hole 4 of the substrate 2. Objective lens holding member 28
A cylindrical coil 32 for focusing control is fixedly installed at the bottom of the cylindrical member 6 and the circular opening 14 of the flat member 12 on the substrate 2. will be located. Further, a flat coil 34 for tracking control is fixed to the Y-direction end face of the objective lens holding member 28, and this coil is connected to the permanent magnet 18,
It will be located opposite 20. The two terminals of the focusing control coil 32 are electrically connected to the wires 24b and 26b, respectively, via a terminal plate 36 attached to the objective lens holding member 28. Furthermore, the two terminals of the tracking control coil 34 are connected to the objective lens holding member 2.
The wires 24a and 26a are electrically connected to the wires 24a and 26a through terminal plates 38 attached to the wires 24a and 26a, respectively. A terminal plate 40 is also attached to the fixed member 22 side, and output terminals of a focusing control drive circuit (not shown) are connected to the wires 24b and 26b via the terminal plate, and the wire 24a , 26a are connected to output terminals of a tracking control drive circuit (not shown).

Further, a balance weight 42 is attached to the objective lens holding means 36, and is adjusted so that the center of gravity of the movable part including the holding means coincides with the point of application of the driving force during focusing and tracking control. .

Next, the operation of the apparatus of this embodiment as described above will be explained.

In the magnetic circuit based on the permanent magnets 8 and 10 described above, the opening 14 of the cylindrical member 6 and the flat member 12
Since a horizontal magnetic field exists between the two and a part of the focusing control coil 32 is located in the magnetic field, the coil 32 is energized from the focusing control drive circuit via the wires 24b and 26b. As a result, a vertical force is applied to the coil due to electromagnetic interaction with the magnetic field,
In this way, the objective lens holding member 28 is moved vertically by a desired distance to perform focusing control.

The wire 24a during this focusing control,
The states of 24b, 26c, and 26b are shown in FIGS. 3a and 3b. As shown in FIG. 3a, when a force in the direction of arrow 44 acts on the objective lens holding member 28, all four wires exist in a plane parallel to the X-Y plane, so as shown in FIG. X as shown by the dotted line in b
All the wires exhibit a similar bend when viewed from the direction, thus the objective lens holding member 28 is approximately aligned with the arrow 4.
4 (ie, upward in FIG. 1).

On the other hand, as shown in FIG.
8 and 20 are arranged so that their polarities are opposite in the Y direction, and these permanent magnets are arranged opposite to each other in two vertical parts of the winding of the tracking control coil 34. wire 24 from the tracking control drive circuit.
By energizing the coil 34 through the windings a and 26a, a force in the X direction is applied to the coil due to electromagnetic interaction with the magnetic fields generated by the permanent magnets 18 and 20, respectively, in the two upper and lower parts of the winding. is made to act. In this way, the objective lens holding member 28 is moved horizontally approximately in the X direction by a desired distance, and tracking control is performed.

Wires 24a, 2 during this tracking control
4b, 26a, and 26b are shown in FIGS. 4a and 4b. As shown in FIG. 4a, when a force in the direction of arrow 45 is applied to the objective lens holding member 28,
A compressive force 46a and a bending force 46b act on the tip of the wire 24a, and the wire 24b
A tensile force 47a and a bending force 47b act on the tip. However, since the wire does not deform due to tensile force or compressive force, when viewed from the Z direction, the wire bends near the intersection position due to the bending force, as shown by the dotted line in Figure 4b. Rotate around the center in the direction of arrow 50. Furthermore, Z
When viewed from the direction, the wire 26a is the same as the wire 24
a, the wire 26b is located at the same location as the wire 24b, and these bend similarly to the wires 24a and 24b, respectively. Therefore, the objective lens holding member 28 is bent only around the Z direction. Rotate in the direction of arrow 50.

In addition, in focusing control and tracking control, the objective lens holding member 28 is strictly Z
Although it does not move only in the direction and the X direction,
In these controls, the amount of movement of the objective lens holding member 28 is determined by the wires 24a, 24b, 26a, 26b.
Since it is minute compared to the length of , it can be considered that it is substantially moving in the Z direction and the X direction, respectively, and there is no problem in controlling focusing and tracking.

In this embodiment, almost no torsional vibration occurs in the Y direction. That is, as shown in FIG. 5, in an attempt to generate torsional vibration around the Y direction, wire pairs 24a and 24b and wire pair 26
When a and 26b apply opposite forces in the X direction,
The wire pair 24a, 24b will be bent around the Z direction in the direction of arrow 48, while the wire pair 26a, 26b will be bent around the Z direction in the direction of arrow 49 (i.e. in the direction of arrow 48). It will be bent in the opposite direction. However, since these four wires are fixed to the objective lens holding member 28, which is a rigid body, such bending of the wires is difficult to occur in reality. Therefore, in the apparatus of this embodiment, the objective lens holding member 28 hardly undergoes torsional vibration around the Y direction.

In the embodiments described above, the intersecting angles of the pair of wires are approximately right angles, which makes it possible to maintain particularly good torsional rigidity and two-dimensional drive efficiency. However, in the present invention, the crossing angle of the pair of wires is not particularly limited and can be set as appropriate. Furthermore, in the above embodiments, the wires intersect at approximately the center of each other, so that both torsional rigidity and two-dimensional drive efficiency can be maintained particularly well. However, in the present invention, the crossing position of the wires is not particularly limited, and may be biased toward the objective lens holding member side or the fixing member side as long as it is somewhat inside from both ends of each wire.

Further, in the above embodiment, two crossed wire pairs are used, but three or more pairs may be arranged in parallel.

[Effects of the Invention] According to the present invention as described above, it is possible to obtain an optical system support device that has an extremely simple configuration, has increased rigidity against torsion, and is capable of efficiently moving an optical system in two-dimensional directions. 2 of the optical system.
It becomes possible to accurately control dimensional drive with a small driving force.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view showing an optical system support device according to the present invention, and FIG. 2 is a cross-sectional view of the optical system support device in an assembled state. FIGS. 3a and 3b are schematic diagrams showing the state of the wire during focusing control in the optical system support device according to the present invention. FIGS. 4a and 4b are schematic diagrams showing the state of the wires during tracking control in the optical system support device according to the present invention. FIG. 5 is a schematic diagram for explaining the rigidity against torsion in the optical system support device according to the present invention. FIG. 6 is a perspective view showing a schematic configuration of a conventional objective lens support device. FIGS. 7 and 8 are schematic diagrams for explaining the occurrence of torsional vibration in a conventional objective lens support device. 22: Fixed member, 24a, 24b, 26a, 2
6b: wire, 28: objective lens holding member, 3
0: Objective lens, 32, 34: Coil.

Claims (1)

[Scope of Claims] 1. An optical system support device that supports an optical system so as to be movable independently in two directions substantially orthogonal to each other, comprising: a member for holding the optical system; a fixing member;
a plurality of rod-shaped support members having bending elasticity, one end of which is fixed to the optical system holding member, and the other end of which is fixed to the fixed member; At least two sets of two wires arranged in a plane substantially perpendicular to the direction of movement and arranged so as to intersect each other between both ends when viewed from the direction of movement are arranged in parallel in relation to the direction of movement. An optical system support device characterized by: 2. The optical system support device according to claim 1, wherein the support member is electrically conductive and is electrically connected to a driving coil attached to the optical system holding member. .