JPH0515124U - Galvano mirror - Google Patents

Abstract

(57) [Abstract] [Purpose] A small structure allows the movable part to be supported in a stable movable state, prevents secondary resonance in which the mirror part is displaced in an unnecessary direction, and does not adversely affect the tracking error detection. Get the mirror. A galvanometer mirror 60 is sandwiched by a movable holder 45 provided with a mirror portion 12, a fixed-side yoke 53 that supports the movable holder 45, a movable-side supporting portion 61, and a fixed-side supporting portion 62. The movable holder 4 and the leaf spring 63 that displaces the movable portion by bending deformation in the plate thickness direction.
A coil 18 and a magnet 16 for moving the movable member 5 in the bending direction are provided, and the movable holder 45 is provided on one side with the central axis M3-M3 of the bending deformation of the leaf spring interposed therebetween.
The yokes 53 are respectively arranged on the other side of the mirror supporting portions.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a galvanometer mirror used in an optical system of a memory device using a magneto-optical disk, and more particularly to a galvanometer mirror having a structure capable of rotating a mirror surface by displacement of bending deformation.

[0002]

[Prior Art]

 As an optical system for reproducing or recording information using light, there is a system using a galvano mirror, which is mainly used for memory devices using magneto-optical disks. FIG. 7 is a perspective view of a conventional galvanometer mirror, and FIG. 8 is a side view of the same. 7 and 8, reference numeral 50 is a mirror portion of the galvanometer mirror, and 50a is its mirror surface. Reference numeral 51 is a movable holder for holding the mirror section 50, and 52 is a coil wound around the outer peripheral surface of the right half of the movable holder 51 in the figure. The movable holder 51 is joined to the tip of the fixed side support portion 53a via an elastic member 55 made of rubber or sponge. The fixed side support portion 53a is integrated with the magnetic yoke 53. The yoke 53 is formed in a U shape, and a pair of magnets 54, 54 are fixed to the inner surface thereof. The magnets 54, 54 face the upper surface and the lower surface of the coil 52, and their different poles face the upper and lower surfaces of the coil 52.

When the coil 52 is energized, the movable holder 51 and the mirror section 50 held by the movable holder 51 and the magnetic poles of the magnets 54, 54 move in the α direction in the figure by the current flowing through the upper and lower surfaces of the coil 52 and the magnetic poles of the respective magnets 54, 54. Is rotated to. The rotation in the α direction is allowed by compression or extension deformation in the thickness direction of the elastic member 55 interposed between the movable holder 51 and the fixed side support portion 53a. In a magneto-optical disk device or the like, by rotating the mirror surface 50a in the α direction, the laser light reflected by the mirror surface 50a and sent in the magneto-optical disk direction is driven in the tracking correction direction.

In this conventional galvanometer mirror, as described above, the movable holder 51 having the mirror portion is supported by the fixed side support portion 53a via the elastic member 55 made of rubber or sponge. However, the elastic coefficient of rubber or sponge is likely to change due to Joule heat of the coil 52 or the rise of environmental temperature, and when the temperature becomes higher, a phenomenon such as drooping occurs, and a stable supporting state can be maintained against temperature changes. There are no drawbacks. In addition, rubber and sponge have the drawback that they tend to deteriorate over time.

Since the elastic member 55 made of rubber or sponge has low rigidity in each direction, the movable holder 51 is not only easy to move in the α direction in the drawing, but also easy to move in the directions other than the α direction. Therefore, there is a drawback that the so-called sub-resonance in which the laser light reflected by the mirror surface 50a is shaken in a direction other than the tracking correction direction is likely to occur.

Further, the conventional galvanometer mirror is not designed in consideration of the load distribution of the movable part including the mirror part 50, the movable holder 51 and the coil 52, and the center of gravity of the movable part and the rotation in the α direction are not considered. The central axis of motion M did not match. Therefore, when no current is flowing in the coil 52, a moment depending on the distance between the center of gravity and the central axis M and the load acts, and the mirror surface 50a faces in either of the tracking correction directions. is there. In particular, as shown in FIG. 7, when the elastic member 55 made of rubber or sponge is used, the deformation direction thereof is not stable, so that the position of the central axis M 1 of rotation in the α direction cannot be set definitely. Therefore, it was physically impossible to match the center of gravity of the movable portion on the central axis M.

[0007]

[Problems to be solved by the device]

 In order to solve the above problems, the applicant of the present application has proposed the galvanomirror disclosed in Japanese Patent Application No. 3-147862. FIG. 9 is a plan view showing an example of the previously proposed galvanometer mirror, and FIG. 10 is an exploded perspective view of the same. In the galvano mirror shown in the figure, the movable portion is composed of the mirror portion 12, the movable holder 45, and the coil 18. The fixed portion is composed of the magnetic yoke 53, the magnet 16 and the support portion 53a.

The central axis M2-M2 of the torsional deformation of the leaf spring 46 and the mirror surface of the mirror portion 12 are parallel to each other. A concave portion 45a is formed on the back side of the movable holder 45 to which the mirror portion 12 is adhesively fixed, and the adhesive surfaces denoted by reference numerals 45b and 45c located on both sides of the concave portion 45a are adhered to both end surfaces of the leaf spring 46. The central portion of the leaf spring 46 is adhesively supported on the adhesive surface 53b of the support portion 53a fixed to the front surface of 53. The coil 18 is fitted and fixed to the rear protruding portion 45d of the movable holder 45 by adhesion.

The magnetic yoke 53 has a Y-shape, and magnets 16 and 16 are fixed to the upper surface and the lower surface of the central protrusion 53c, respectively. The coil 18 fixed to the movable holder 45 is inserted into the yoke 53 and faces the magnets 16, 16 fixed to the central projection 53c. The driving force is generated by the current flowing through the coil 18 and the magnetic field of the magnet 16 fixed to the yoke 53. The movable portion is driven in the .beta.2 direction about the rotation center axis M2-M2 by the torsional deformation of the free portion of the leaf spring which is not adhered.

In this galvanometer mirror, in the movable portion, the weight distribution on one side (the side supporting the mirror portion 12) sandwiching the central axis M2-M2 and the weight distribution on the other side (the coil 18 side) are It is well balanced and the center of gravity of the moving part is on the central axis M2-M2.

However, even with the Galvano mirror having the above-described configuration, there is a case where a sub-resonance occurs in which the mirror portion is displaced in an unnecessary direction as shown below. In this galvano mirror, the long side direction of the leaf spring 46 is arranged in the direction of the central axis M2-M2, and fixed at three points, that is, at both ends and at the center, and the part which is not fixed by adhesion is described above. The movable part is rotated by twisting and deforming about the central axis M2-M2. In this structure, the leaf spring 46 is not only torsionally deformed, but also the free portion of the leaf spring 46, which is not bonded, is easily bent and deformed about the axes L1 and L2 (see FIG. 10). Therefore, when the movable portion is driven in the β2 direction, the sub-resonance in the bending direction is likely to occur.

As a result, a secondary resonance occurs in which the laser light reflected by the mirror surface 12a is shaken in a direction other than the tracking correction direction, so that the laser light cannot be accurately focused on the recording surface of the disk, resulting in a tracking error. However, there is a problem that it may adversely affect the detection of. In particular, when a sub-resonance occurs due to the bending deformation of the leaf spring 46, this resonance causes the spot focused on the disk recording surface to be swung in the tangential direction (direction along the track), which results in a tracking error signal and a focus error signal. There is an inconvenience such as crosstalk.

The present invention solves the above-mentioned conventional problems, and provides a galvanometer mirror that can prevent a secondary resonance in which a mirror portion is displaced in an unnecessary direction, and that does not adversely affect tracking error detection. Has a purpose.

[0014]

[Means for Solving the Problems]

 The galvanometer mirror according to the present invention comprises a movable part provided with a mirror, a fixed part for supporting the movable part, and an elastic member provided between the movable part and the fixed part for displacing the movable part by its bending deformation. And an electromagnetic drive mechanism for moving the movable portion in the bending direction, and the elastic member is a leaf spring that bends and deforms in the plate thickness direction. It is characterized in that the elastic member is a resin molded body formed into a hinge structure having a thin portion that can be bent and deformed.

[0015]

[Action]

 When a leaf spring that bends and deforms in the plate thickness direction is used as the elastic member in the above means, the movable portion is less likely to be displaced in a direction other than the bending deformation direction of the leaf spring, and the problem of sub-resonance is less likely to occur. Also, when a resin molded body having a thin portion that can be bent and deformed as the elastic member is formed into a hinge structure, similarly, sub-resonance other than bending deformation does not easily occur, and only supports the movable part. The support structure is simple and the number of parts used is small.

[0016]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. 1 is a plan view of a galvano mirror according to a first embodiment of the present invention, and FIG. 2 is an exploded perspective view of the same. The same members as those shown in FIGS. 9 and 10 described above are designated by the same reference numerals, and detailed description thereof will be omitted. The difference between the galvano-mirror 60 shown in the figure and the galvano-mirror shown in FIGS. 9 and 10 is that a leaf spring (elastic member) 63 that bends and deforms in the thickness direction is attached to the movable portion side support portion 61 and the fixed portion side. The movable portion side support portion 61 is sandwiched by a support portion 62, and the movable portion side support portion 61 is adhesively fixed in a concave portion 45a formed on the back surface of the movable holder 45, and the fixed portion side support portion 62 is located at the central protrusion 53c of the yoke 53. It is that it is adhesively fixed to.

The leaf spring 63 is formed in a square shape, and its long side portions 63a, 63a are adhesively fixed to the movable portion side supporting portion 61 and the fixed portion side supporting portion 62, and the short side portions 63b, 63b are Most parts are free-deformable parts that are not fixed. Further, the plate bar 63 is configured to be bent and deformed about a central axis M3-M3 passing through a short side portion which is a freely deformable portion thereof.

Although the leaf spring 63 is formed of a metal spring material here, it may be formed of a resin plate. Further, a damping material such as rubber or elastomer may be attached to the leaf spring 63, or the entire surface of the leaf spring 63 may be coated with a damping material. As a result, the amplitude due to the resonance vibration of the leaf spring 63 can be suppressed. When used in a magneto-optical disk device, the frequency at which the mirror section 12 operates is set in a region that does not match the primary resonance frequency of the bending vibration of the leaf spring 63, and the leaf spring is not subjected to a normal tracking correction operation. Although 63 is prevented from being in a resonance state, the provision of the damping material can suppress the resonance amplitude when the leaf spring resonates due to external vibration or the like.

Even in this galvanometer mirror 60, in the movable part, the weight on one side (the side supporting the mirror part 12) sandwiching the central axis M3-M3 and the weight on the other side (the coil 18 side) are set. The weight distribution is well balanced, and the center of gravity of the movable part coincides with the central axis M3-M3. Therefore, the mirror portion 12 does not tilt under its own weight when it is not driven. Therefore, not only can stable operation be performed, but the attitude of the movable part having the mirror part can be stabilized at the neutral position regardless of the orientation of the galvanometer mirror with respect to the gravity direction. The overall structure is such that the support portion of the mirror portion 12 in the movable portion is located on one side and the fixed portion is located on the other side with the central axis M3-M3 of the bending deformation of the leaf spring 63 interposed therebetween. It has a small size.

Next, the configuration and operation of an optical system using a galvano mirror will be described. FIG. 3 is a perspective view showing the arrangement of each element of the recording / reproducing optical system in the magneto-optical disk device. In the optical system shown in the figure, an objective lens 21 and a reflecting prism 22 are mounted on an optical head that moves along the recording surface of a magneto-optical disk. The optical head is driven in the X direction shown in FIG. 3 along the recording surface by the driving force of a linear motor or the like. The optical axis O1 of the objective lens 21 is perpendicular to the recording surface of the magneto-optical disk. The reflecting prism 22 is arranged in such a direction that light (optical axis O 2) substantially parallel to the recording surface of the magneto-optical disk can be reflected in the optical axis O 1 direction of the objective lens 21. Although not shown here, the optical head is provided with a focus correction mechanism so that the objective lens 21 is finely adjusted so that the focus of the objective lens 21 is aligned with the recording surface of the magneto-optical disk. It has become.

A light emitting element 23 such as a semiconductor laser is provided on the side of a fixed portion such as a chassis on which the optical head is movably supported. The laser light (optical axis O3) emitted from the light emitting element 23 passes through the collimator lens 24 to become a parallel light beam, which is reflected by the beam splitter 25 in the direction perpendicular to the optical axis O4. Then, it is reflected in the direction of the optical axis O2 by the mirror portion 12 of the galvanometer mirror 60. Further, reference numeral 27 is a monitor light receiving element. Similarly, in the light receiving detection system provided on the fixed side such as the chassis, the light reflected from the magneto-optical disk passes through the beam splitter 25, the Wollaston prism 28, the plano-concave lens 29 and the cylindrical lens 30, and the light receiving element. The light is received by the (pin photo diode) 31.

When the galvano mirror 60 shown in the first embodiment is used in the optical device shown in FIG. 3, the mirror surface 12a of the mirror section 12 and the central axes M3 to M3 of bending deformation are parallel to each other. Therefore, the mirror surface 12a of the mirror portion 12 is oriented so that the optical axis O4 can be reflected in the O2 direction, and the central axis M3-M3 of the bending deformation of the leaf spring 63 is inclined with respect to the optical axes O4 and O2. By rotating the mirror section 12 in the β 3 direction around the central axis M 3 -M 3, the spot of the beam irradiated on the recording surface of the disk is swung in the substantially radial (RAD) direction, and tracking correction is performed.

Next, a second embodiment of the present invention will be described with reference to the drawings. FIG. 4 is a plan view of a galvanometer mirror according to a second embodiment of the present invention, and FIG. 5 is an exploded perspective view of the same. The same members as those of the galvano mirror 60 described above are designated by the same reference numerals, and detailed description thereof will be omitted. In the Galvano mirror 10 shown in the figure, the movable portion is composed of a mirror portion 12, a movable holder 11, a balancer 13, a movable portion side support portion 14 and a coil 18. The mirror portion 12 is fixed on one outer surface of the holder 11 so as to be inclined with respect to the center of rotation M1 -M1. A balancer 13 is fixedly provided on the other outer surface of the holder 11 so that the weight is balanced. The movable portion side support portion 14 is fixed to the inner surface of the movable holder 11. The front end faces 18a and 18b of the coil 18 are fixedly adhered to the rear end faces 11a and 11b of the movable holder 11.

The fixed portion is composed of the magnetic yoke 15, the magnet 16, and the fixed portion side support portion 62. The magnetic yoke 15 has a Y-shape, and magnets 16 and 16 are fixed to the inner surfaces of the upper and lower portions, respectively. The fixed side support portion 62 is joined to the end surface 15b of the central protrusion 15a of the yoke 15. The coil 18 fixed to the movable holder 11 is inserted into the central protrusion 15a of the yoke 15 and faces the magnets 16 and 16 fixedly provided on the upper and lower portions of the yoke 15.

Similar to the first embodiment, the leaf spring 63 is sandwiched between the movable portion side support portion 14 and the fixed portion side support portion 62. The long side portions 63a, 63a are adhesively fixed to the fixed portion side support portion 62 and the movable portion side support portion 14, and most of the short side portion 63b is a non-fixed free deformable portion. The bending central axis constitutes the above-described rotation center axis M1-M1. As a result, the movable portion can move in the .beta.1 direction about the axis M1-M1 in FIG. 5 with respect to the fixed portion due to the bending deformation of the leaf spring 63. The overall structure is such that the support portion of the mirror portion 12 in the movable portion is located on one side and the fixed portion is located on the other side with the central axis M1-M1 of the bending deformation of the leaf spring 63 interposed therebetween. It has a small size.

In the galvano mirror 10 having the above structure, different poles of the upper and lower magnets 16 and 16 face the upper and lower surfaces of the coil 18, and when the coil 18 is energized, the current direction is the same as the upper surface of the coil. It is in the opposite direction to the bottom surface. Therefore, an electromagnetic force is generated by the current direction and the magnetic fluxes from the upper and lower magnets 16, 16, and this becomes a driving force for the movable portion. By this driving force, the free portion in the middle of the adhesive portion of the leaf spring 63 is bent and deformed. Due to this bending deformation, the movable portion is rotated in the β1 direction to perform the tracking correction operation.

Further, in the above galvanometer mirror, the support portion of the mirror portion 12 is arranged on one side and the coil 18 is arranged on the other side with the central axis M1-M1 direction interposed therebetween, and the center of gravity of the movable portion is caused by the loads distributed on both sides. , On the central axis M1-M1. Therefore, the mirror portion 12 does not tilt under its own weight in a state where it is not driven. Therefore, similar to the first embodiment, not only stable operation is possible, but the attitude of the movable part having the mirror part is stabilized at the neutral position regardless of the orientation of the galvanomirror with respect to the gravity direction. ..

When the mirror section 12 of the galvano mirror shown in the second embodiment is used in the optical device shown in FIG. 3, the central axes M1 to M1 of the bending deformation of the leaf spring 63 are the optical axes O4. The mirror portion 12 is driven in the β1 direction about this central axis so that the spot focused on the recording surface of the magneto-optical disk is aligned with the radial (RAD) direction, that is, the meridional surface. Then, the tracking correction operation is performed.

Next, a third embodiment of the present invention will be described with reference to the drawings. FIG. 6 is an exploded perspective view of a galvanometer mirror according to a third embodiment of the present invention. The same members as those in the first embodiment described above are designated by the same reference numerals and detailed description thereof will be omitted. The galvano-mirror 70 shown in FIG. 6 differs from the galvano-mirror 60 according to the first embodiment in that a resin molding 71 having a hinge structure having a bendable thin portion 72 is provided as an elastic member. There is something. The resin molded body 71 is formed in a generally V shape, and the thinned portion 72 sets the pivoting center axes M3-M3. Then, the front surface 71a is formed in a flat shape, and is adhesively fixed in the recess 45a on the back side of the movable holder 45. Further, the rear surface 71b is formed in a concave shape, and upper and lower step portions 71c are fitted to the upper and lower surfaces of the magnets 16, 16 fixed to the central protruding portion 53c of the yoke 53, whereby the yoke 53 is formed. The molded body 71 is positioned and adhesively fixed. In this way, by fitting the rear surface 71b and the magnets 16, 16 to each other, the elastic member can be attached without displacement.

The driving force is generated by the current flowing through the coil 18 and the magnetic field of the magnet 16 fixed to the yoke 53. When this driving force acts on the movable portion, the movable portion is driven in the .beta.3 direction about the rotation center axis M3-M3 due to the bending deformation of the thin portion 72. Further, the structure of the galvanometer mirror 70 is similar to that of the first embodiment, in which the support portion of the mirror portion 12 is located on one side and the coil 18 is located on the other side with the central axis M3-M3 sandwiched therebetween, and the gravity center of the movable portion causes the center of gravity of the movable portion. Are located on the central axis M3-M3.

Also in this third embodiment, the central axis M3-M3 of bending deformation of the resin molded body 71 extends in the same direction as in the first embodiment of FIG. Therefore, when used in the optical device shown in FIG. 3, the spots of the beam irradiated on the recording surface of the disk are swung in a substantially radial (RAD) direction, and tracking correction is performed, as in the first embodiment.

According to the third embodiment, the leaf spring and the member for supporting the leaf spring are unnecessary, and the damping member is not required unlike the case of using the leaf spring. The number of parts is reduced. Further, since the work of fixing the leaf spring is unnecessary, the assembling work becomes easy. The movable portion shown in FIGS. 4 and 5 may be operably supported by the resin molding 71 having the thin portion 72 shown in FIG. In the third embodiment, the thin portion 72 may be a leaf spring, and the leaf spring may be integrally molded with a resin member to form a resin molded body.

In the first and second embodiments, since the movable part operates by bending deformation of the leaf spring 63, a direction other than the bending deformation direction of the leaf spring 63, for example, the vertical axis L 1 shown in FIG. , L2 and the like are less likely to be deformed in the direction of rotation, so that the frequency of sub-resonance in this direction is in a very high region. Therefore, during the tracking correction operation, the spot focused on the disk is not shaken in the tangential direction, and the stable tracking correction operation can be performed. Similarly, in the third embodiment as well, since the movable portion operates due to the bending deformation of the thin portion 72, an operation in a direction other than the bending deformation direction is unlikely to occur, and the secondary resonance can be similarly prevented. Although the above embodiments have been described with respect to the case where the galvanomirror is used in the magneto-optical disk device, it can be used in other disk devices and optical devices other than the disk device.

[0034]

[Effect of the device]

 As described above, according to the present invention, bending deformation is caused by the leaf spring or the thin portion, and the mirror portion is shaken by this, and tracking correction and the like are performed, so that the direction orthogonal to the tracking direction of the mirror portion, that is, the tangential direction. It is less likely that vibrations in the same direction and secondary resonance in the same direction will occur. Therefore, stable tracking correction operation is performed. According to the third aspect of the invention, since the elastic support member is composed of one resin molded body, the number of parts is small and the assembly is easy.

[Brief description of drawings]

FIG. 1 is a plan view of a galvanometer mirror according to a first embodiment of the present invention.

FIG. 2 is an exploded perspective view of the galvanometer mirror according to the first embodiment.

FIG. 3 is a perspective view showing an arrangement of optical members of a magneto-optical disk device using a galvano mirror.

FIG. 4 is a plan view of a galvanometer mirror according to a second embodiment of the present invention.

FIG. 5 is an exploded perspective view of a galvanometer mirror according to a second embodiment,

FIG. 6 is an exploded perspective view of a galvanometer mirror according to a third embodiment of the present invention.

FIG. 7 is a perspective view of a conventional galvanometer mirror.

FIG. 8 is a side view of a conventional galvanometer mirror.

FIG. 9 is a plan view showing an example of the previously proposed galvanometer mirror.

FIG. 10 is an exploded perspective view showing an example of a galvano mirror proposed previously.

[Explanation of symbols]

 12 mirror part 12a mirror surface 16 magnet 18 coil 45 movable holder 61 movable part side support part 62 fixed part side support part 63 leaf spring

Claims (3)

[Scope of utility model registration request] 1. A movable part provided with a mirror, a fixed part for supporting the movable part, an elastic member provided between the movable part and the fixed part for displacing the movable part by bending deformation thereof, An electromagnetic drive mechanism for moving the portion in the bending direction, and a galvano mirror. 2. The galvanometer mirror according to claim 1, wherein the elastic member is a leaf spring that is bent and deformed in the thickness direction. 3. The galvano mirror according to claim 1, wherein the elastic member is a resin molded body formed in a hinge structure having a thin portion that can be bent and deformed.