JP3413736B2 - Two-axis actuator - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compact disc,
The present invention relates to a biaxial actuator for an optical pickup used for recording and reproducing a signal of an information recording medium for data storage using a magneto-optical disk or the like. 2. Description of the Related Art Hitherto, reproduction or recording of information signals on an optical disk, for example, a so-called compact disk (CD) or a magneto-optical disk has been performed using an optical pickup. This optical pickup includes a semiconductor laser as a light source, an objective lens, an optical system, and a photodetector. In an optical pickup, a light beam emitted from a semiconductor laser is focused on a recording surface of an optical disk by an objective lens via an optical system. The return light beam from the optical disc is separated from the light beam emitted from the semiconductor laser by the optical system and guided to the photodetector. The light beam emitted from the semiconductor laser follows the displacement of the optical disk in a direction orthogonal to the surface direction of the optical disk generated due to the warp of the optical disk or the like, so that it is focused on the recording surface of the optical disk, The position of the objective lens in the optical axis direction is adjusted. At the same time, the position in the direction perpendicular to the optical axis of the objective lens is adjusted so that the position of the spot on the optical disk of the light beam emitted from the semiconductor laser follows the eccentricity of the optical disk or the meandering of the track formed on the optical disk. Is done. The focus position of the light beam emitted from the semiconductor laser and the adjustment of the spot position on the recording surface of the optical disk are adjusted by moving the objective lens in the optical axis direction of the objective lens and in the direction perpendicular to the optical axis. This is done by adjusting. An electromagnetically driven actuator is used to adjust the position of the objective lens. This actuator is called an objective lens actuator or a biaxial actuator, and includes a bobbin to which an objective lens is attached, a plurality of elastic support members, and a driving unit that generates a driving force.
The bobbin is supported by the plurality of elastic support members such that the position in the optical axis direction of the objective lens, that is, the focus position, and the position in the direction orthogonal to the optical axis of the objective lens, that is, the tracking position, are adjustable with respect to the fixed portion. ing. Hereinafter, an example of the biaxial actuator will be described with reference to FIG. [0005] Such a two-axis actuator is configured, for example, as shown in FIG. In FIG. 8, the biaxial actuator 1 includes a lens holder 2 having an objective lens 2a attached to the tip thereof, and a coil bobbin 3 attached to the lens holder 2 by bonding or the like. The lens holder 2 has two ends perpendicular to the fixed part 4 by two pairs of elastic support members 5 having one end on both sides of the lens holder 2 and the other end fixed to the fixed part 4. It is supported so as to be movable in directions, that is, in a tracking direction indicated by reference numeral Trk and a focusing direction indicated by reference numeral Fcs. The coil bobbin 3 is configured as shown in FIG. That is, the coil bobbin 3 includes an opening 3a penetrating vertically, a focusing coil 3b wound so as to surround the opening 3a, and a front side of the focusing coil 3b.
And tracking coils 3c provided at two positions on the left and right. Each of the coils 3b and 3c is wound by using a winding machine, and the winding ends of the coils 3b and 3c are provided so as to protrude toward the fixed portion side of the coil bobbin 3, as shown in FIG. The terminal pins 3d are wound by a winding machine and then connected by soldering. When the coils 3b and 3c are energized, the magnetic flux generated in the coils 3b and 3c interacts with the magnetic flux generated by the yoke 6 attached to the fixed part 4 and the magnet 7 attached thereto. It has become. Further, the elastic supporting member 5 is formed of an elastic body and fixed between the lens holder 2 and the fixing portion 4 so as to be parallel to each other. Elastic support member 5
The viscous body 8 is applied to an end region of the substrate and plays a role of a damper. According to the two-axis actuator 1 configured as described above, when a driving voltage is supplied to each coil from the outside, the magnetic flux generated in each coil mutually interacts with the magnetic flux generated by the yoke 6 and the magnet 7. In operation, the coil bobbin 3 can be moved with respect to the tracking direction Trk and the focusing direction Fcs. Thus, the objective lens 2a attached to the lens holder 2 can be appropriately moved in the focusing direction and the tracking direction. [0011] However, in the biaxial actuator 1 having such a configuration, the coil bobbin 3 is attached to the lens holder 2 by the coil bobbin 3.
Is inserted into the opening of the lens holder 2 and the coil bobbin 3 is bonded in the opening of the lens holder 2 with an adhesive. For this reason, it is difficult to position the coil bobbin 3 in the opening of the lens holder 2 and there is a problem that the assembling workability is poor. Further, when the coil bobbin 3 is adhered to the lens holder, the adhesive may protrude. Therefore, there has been a problem that the sticking adhesive reduces the mounting accuracy of the coil bobbin 3 to the lens holder 2. When the lens holder is divided into an upper part and a lower part, and the upper part and the lower part are integrally formed by bonding the upper part and the lower part to each other with an adhesive, the upper part and the lower part of the lens holder are separated from each other. After being integrally formed by bonding with an adhesive, a coil bobbin is inserted into the opening of the lens holder and bonded with the adhesive. Therefore, also in this case, as in the case of the integrally formed lens holder, there is a problem that the assembling workability is poor and the mounting accuracy is reduced. SUMMARY OF THE INVENTION In view of the above, it is an object of the present invention to provide a two-axis actuator in which a coil bobbin can be easily and accurately mounted on a lens holder. According to the present invention, there is provided a lens holder for supporting an objective lens, an elastic support member for elastically supporting the lens holder with respect to a fixed portion, and A coil bobbin that is inserted into the opening of the lens holder and around which a focusing coil and a tracking coil are wound, and between the opening of the lens holder and the outer surface of the coil bobbin. This is achieved by a biaxial actuator comprising an adhesive reservoir into which the adhesive for bonding is poured. According to the above construction, the lens holder for holding the objective lens is supported by the elastic supporting member, so that the focusing coil or the tracking coil is energized, whereby the tension of the elastic supporting member is increased. The lens holder is moved along the focusing direction or the tracking direction to perform focusing or tracking of the objective lens. Here, the coil bobbin is formed by pouring the adhesive in the above-mentioned adhesive reservoir into an integrated lens holder or when bonding the upper and lower lens holders to each other with an adhesive. At the same time, since the coil bobbin can be integrally bonded to the lens holder, the positioning of the coil bobbin with respect to the lens holder is accurately performed. When the adhesive reservoir is defined by an inner surface defining an opening of the lens holder or upper and lower openings of the lens holder and an outer surface of the coil bobbin, the molding of the lens holder is performed. At this time, an adhesive pool may be formed. In the case where the adhesive reservoir is defined by an inner surface defining an opening at an upper portion of the lens holder, an upper surface of the lower portion of the lens holder, a rising piece extending upward from the upper surface, and an outer surface of the coil bobbin. In the method, an adhesive reservoir can be formed when the lens holder is formed, and the adhesive is applied to the adhesive reservoir from above. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to FIGS. In addition, since the Examples described below are preferred specific examples of the present invention, various technically preferable limitations are given. However, the scope of the present invention particularly limits the present invention in the following description. The embodiment is not limited to these embodiments unless otherwise stated. FIGS. 1 to 3 show an embodiment of a biaxial actuator according to the present invention. 1 to 3, a biaxial actuator 10 includes a lens holder 11,
Coil bobbin 12, a plurality of elastic support members 13a, 13
b, 13c, 13d, the fixing portion 14, and the yoke 31. As shown in FIG. 3, the lens holder 11 is divided into an upper part 11U and a lower part 11L by a horizontal dividing line, and they are adhered to each other by an adhesive. Further, FIG.
As shown in FIG.
1a is formed, and a concave portion 11b to which an objective lens is attached is formed. A hole through which a light beam emitted from the semiconductor laser or a return light beam from the recording surface of the optical disk passes is formed on the bottom surface of the concave portion 11b. In the concave portion 11b of the lens holder 11,
The objective lens 11c is attached by bonding or the like. Further, the lens holder 11 is supported by elastic supporting members 13a, 13b, 13c and 13d so as to be movable in the focusing direction Fcs and the tracking direction Trk. The coil bobbin 12 has an opening 12a into which a magnetic circuit including a yoke 31 integrated with the base and a magnet 32 attached to the inner surface of the inner yoke 31a is inserted, and a focusing coil 12b. And a tracking coil 12c. The focusing coil 12b is wound around the coil bobbin 12 along an axis parallel to the optical axis of the objective lens 11c. The tracking coil 12c is formed by winding the coil in an elliptical or rectangular shape, and is attached to a winding portion formed on one side surface of the focusing coil 12b. The upper surface of the coil bobbin 12 is covered by a yoke bridge 36. The yoke bridge 36 may form a closed magnetic circuit together with the yoke portion of the magnetic circuit. The coil bobbin 12 is used for the focusing coil 1.
2b and the opening 11a formed in the lens holder 11 with the tracking coil 12c attached.
Attached to. The elastic support members 13a, 13b, 13
It is preferable that c and 13d have conductivity and have spring properties, and for example, materials such as phosphor bronze, beryllium copper, titanium copper, tin-nickel alloy, and stainless steel are used. Accordingly, in the present embodiment, for example, a leaf spring suspension is formed by a thin sheet metal, and is fixed between the lens holder 11 and the fixing portion 14 so as to be parallel to each other. As a result, the elastic support members 13a, 13b, 13c, and 13d apply a drive current from an external current supply unit (not shown) to the terminals of the focusing coil 12b and the tracking coil 12c wound around the coil bobbin 12. You may be comprised so that it may supply. Also, the elastic support members 13a,
A viscous body 16 for damping is applied to the end regions 15 of 13b, 13c, and 13d and hardened. This effectively prevents harmful vibration when the biaxial actuator 10 is moved in the tracking and focusing directions. The fixing portion 14 is attached to the adjustment plate 30 in a state where the lens holder 11 and the fixing portion 14 are connected by four elastic support members 13a, 13b, 13c, 13d. The adjustment plate 30 is for adjusting the fixing position of the fixing portion 14 when assembling the biaxial actuator 10. And adjustment plate 3
0 is relative to the base 31 formed integrally with the yoke.
It is fixed by soldering or the like. This adjustment plate 30
Is mounted on the base 31 by soldering the rising portions 30a extending upward from both sides near the rear end of the adjustment plate 30 to the rising portions extending upward from both sides of the rear end of the base 31. Is done. The base 31 is provided with a pair of yokes 31a and 31b constituting the magnetic circuit by bending the ends of the base 31 on the objective lens side upward. A permanent magnet 32 is provided on an inner surface of the inner yoke 31a facing the opposing yoke 31b. Thus, the pair of yokes 31a and 31b and the permanent magnet 32 form a magnetic circuit. And
As described above, when the fixing portion 14 is attached to the base 31, the focusing coil 12b and the tracking coil 12c attached to the coil bobbin 12 are inserted into the gap between the opposed yoke 31b and the permanent magnet 32. . At the same time, the inner yoke 31a and the permanent magnet 32
Is inserted into the opening 12a of the coil bobbin 12. Further, in the biaxial actuator 10 according to the present embodiment, the upper part 11U of the lens holder 11 is provided.
Has a notch 11d defining an adhesive reservoir 17 near the front end of an inner surface defining an opening 11a penetrating vertically in the drawing. On the other hand, the lower portion 11L of the lens holder 11 is provided with a rising piece 11e extending upward from the inside near the front end of the inner surface defining the opening 11a. Thereby, when the coil bobbin 12 is inserted into the opening 11a in a state where the upper portion 11U and the lower portion 11L of the lens holder 11 are combined, the cutout portion 11 of the upper portion 11U of the lens holder 11 is formed.
d, rising piece 11e of lower part 11L of lens holder 11
And the outer side surface of the coil bobbin 12, the adhesive pool 1
7 is defined from the periphery, and the adhesive reservoir 17 is defined from below by the upper surface of the lower portion 11L of the lens holder 11. Thus, an upwardly open adhesive reservoir 17 can be defined. In this case, since the adhesive reservoir 17 is open upward, the elastic support members 13a, 13b, 13c and 13d are connected to the plurality of lens holders 11 and the fixing portions 14 as shown in FIG. When formed integrally by press molding or the like for outsert molding, the elastic support members 13a, 13b, 13c, 1
For the lens holder 11 formed integrally with 3d, for the opening 11a of each lens holder 11,
The coil bobbin 12 is inserted from above, and the adhesive 18 can be injected into the adhesive reservoir 17 from above. As shown in FIG. 9, the coil bobbin 12 has four terminal pins, two at the upper and lower ends, protruding toward the fixed portion 14 at the rear side surface. 12d. This terminal pin 12d has
The winding terminals of the focusing coil 12b and the tracking coil 12c wound around the coil bobbin 12,
It is a jellyfish. In this case, the winding terminal is lapped with the insulation coating removed, or after the ligation is performed, the insulation coating of only the surface portion is removed by, for example, scribing. Each terminal pin 12d is connected to the coil bobbin 1
2 is formed integrally with the coil bobbin 12 by using the same molding material as that of the second molding material, preferably a material having an appropriate rigidity. On the other hand, the opening 11 of the lens holder 11
a, the connection terminals, preferably each of the elastic support members 13a, 13b, 13a, are exposed such that when the coil bobbin 12 is inserted, they are exposed at positions where they can come into contact with the respective terminal pins 12d.
Inside ends of c and 13d are provided. The biaxial actuator 10 according to the present embodiment
Is configured as described above, and the operation and operation will be described below. Currents based on the focus servo signal and the tracking servo signal are supplied to the focusing coil 12b and the tracking coil 12c wound on the coil bobbin 12, respectively. This allows
The lens holder 11, that is, the objective lens 11c is driven in the focus direction Fcs and the tracking direction Trk by the DC magnetic field of the magnetic circuit and the alternating magnetic field generated from the focusing coil 12b and the tracking coil 12c. The elastic support member 13 serves as a damper.
Since the viscous material 16 is applied to the end regions 15 of the fixed portions 14 of the a, 13b, 13c, and 13d on the fixing portion 14 side and is hardened, desired f0, Q, and damping characteristics can be obtained. Thereby, at the time of focusing or tracking, the vibration of the elastic support members 13a, 13b, 13c, 13d can be attenuated. Here, the upper part 11U of the lens holder 11
When assembling with the lower surface of the lens holder 11 and the upper surface of the lower portion 11L opposed to each other, the upper portion 11U and the lower portion 11L of the lens holder 11 are first aligned and overlapped, and the coil bobbin 12 is inserted into the opening 11a of the lens holder 11. And positioning. Thereafter, an adhesive 18 is injected into an adhesive reservoir 17 defined by the opening 11 a of the lens holder 11 and the outer surface of the coil bobbin 12. As the adhesive 18, for example, an ultraviolet curable adhesive is used. As a result, the adhesive in the adhesive reservoir 17 contacts the notch 11d of the upper portion 11U of the lens holder 11, the rising piece 11e and the upper surface of the lower portion 11L of the lens holder 11, and the coil bobbin 12
Contacts the outside surface of the Thereby, for example, an optical fiber (not shown) is applied to the adhesive 18 in the adhesive reservoir 17.
The adhesive 1 is irradiated with ultraviolet rays through
8 is hardened, whereby the upper part 1 of the lens holder 11 is
The 1U and lower part 11L and the coil bobbin 12 can be integrally bonded and fixed. Thus, the coil bobbin 12
Can be easily and accurately performed on the lens holder 11. In this case, since the insertion direction of the coil bobbin 12 and the injection direction of the adhesive 18 are the same, the adhesive 18
Of the elastic supporting members 13a, 13b, 13c,
13d and does not interfere with the adhesive 18d.
Since the optical fiber for ultraviolet light guide for curing of the adhesive can be easily approached to the adhesive reservoir 18, the assembly operation by the automatic machine can be easily performed. Further, since the adhesive 18 can be injected from above, the elastic support members 13a, 13c and 13c supported by the upper portion 11U and the lower portion 11L of the lens holder 11 are provided.
Since b and 13d can be arranged close to each other, the entire lens holder 11 can be configured to be thin. The terminal pins 12d of the coil bobbin 12 have the ends of the windings of the coils 12b and 12c.
The conductive wire is exposed by removing the insulating coating. Thereby, the coil bobbin 12 is attached to the lens holder 1.
The terminal pins 12d are inserted into the openings 11a of the lens holder 11, respectively.
It contacts the connection terminals (not shown) exposed in 1a, for example, the inner ends of the elastic support members 13a, 13b, 13c, 13d. Thereby, each coil 12b, 12c
Are respectively connected to the elastic support members 13 from the terminal pins 12d.
Through the a, 13b, 13c, and 13d, the fixed portion 14 can be connected to an external drive circuit. In this case, since the winding terminals of the coils 12b and 12c are not soldered at the terminal pins 12d, the weight of the terminal pins 12d varies depending on the amount of solder used for soldering. Absent. Therefore, the variation in the weight balance between the coil bobbin 12 and the lens holder 11 is reduced. Thus, as shown in FIG. 6, the vibration characteristics on the Y axis are improved. When the terminal pins 12d are arranged on both sides of the lens holder 11 as shown in FIG. 7, the vibration characteristics on the X axis are improved. In the embodiment described above, the elastic support members 13a, 13b, 13c, and 13d are described as being simply fixed to the lens holder 11 and the fixing portion 14, respectively. Fixed part 1
Obviously, the wire 4 may be integrally formed by insert formation or the like. The lens holder 11 has an upper part 11U.
And the lower part 11L, but is not limited to this.
Obviously, the present invention can be applied to an integrally formed lens holder. As described above, according to the present invention, it is possible to provide a two-axis actuator in which the coil bobbin can be easily and accurately mounted on the lens holder.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic perspective view showing the entire configuration of an embodiment of a biaxial actuator for an optical pickup according to the present invention as viewed from the front. FIG. 2 is a schematic perspective view showing the biaxial actuator of FIG. 1 as viewed from the rear. FIG. 3 is an exploded perspective view of the biaxial actuator of FIG. FIG. 4 is a partially enlarged sectional view showing an adhesive reservoir in the biaxial actuator of FIG. 1; FIG. 5 is a schematic plan view showing a state in which a plurality of lens holders are integrally outsert molded with an elastic supporting member in the biaxial actuator of FIG. 1; FIG. 6 is a schematic side view showing a weight balance regarding a horizontal axis in the biaxial actuator of FIG. 1; FIG. 7 is a schematic side view showing a weight balance on a longitudinal axis by terminal pins having different configurations in the biaxial actuator of FIG. 1; FIG. 8 is a schematic perspective view showing an overall configuration of an example of a conventional biaxial actuator for an optical pickup. FIG. 9 is a schematic perspective view showing a configuration of a coil bobbin in the biaxial actuator of FIG. 8; DESCRIPTION OF SYMBOLS 10 Biaxial actuator 11 Lens holder 11a Opening 11b Recess 11c Objective lens 11d Notch 11e Rising piece 12 Coil bobbin 12a Opening 12b Focusing coil 12c Tracking coil 12d Terminal pins 13a, 13b, 13c, 13d Elasticity Support member 14 fixing portion 15 end region 16 viscous body 17 adhesive reservoir 18 adhesive

────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-7-29194 (JP, A) JP-A-6-162534 (JP, A) JP-A-4-328336 (JP, A) JP-A-6-162534 274910 (JP, A) JP-A-8-147733 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G11B ^7/ 09-7/10

Claims (1)

(57) [Claim 1] A lens holder which is divided into an upper part and a lower part which support an objective lens and is integrally bonded, and an elasticity which elastically supports the lens holder with respect to a fixed part. A support member, a coil bobbin inserted into the opening of the lens holder, around which a focusing coil and a tracking coil are wound, and a coil bobbin between the opening of the lens holder and an outer surface of the coil bobbin. Bei and a glue reservoir in which the adhesive is poured for bonding against
The adhesive pool defines an opening above the lens holder.
The upper surface of the lower part of the lens holder and the upper surface
And the outer surface of the coil bobbin.
A two-axis actuator characterized by being defined .