JPH0452814Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to an actuator in an optical pickup used for reproducing information recorded on an optical recording disk or recording information on such a disk.

[Conventional technology]

Generally, in an optical pickup, a light source, an optical system such as a beam splitter, and a photodetector are attached to the optical pickup body, and an actuator with an objective lens is attached to the optical pickup body to direct the light from the light source through the objective lens. The light is then irradiated onto the disk in a spot-like manner, and the reflected light is received by a photodetector via an objective lens.

Various types of actuators have been proposed in the past for such optical pickups, but generally speaking, focusing coils and tracking are attached to a movable member that holds the objective lens and supports it so that it can be displaced in the focusing and tracking directions. The movable member can be tracked by attaching coils partially overlapped and applying magnetic flux to these coils to supply a focusing error signal to the focusing coil and a tracking error signal to the tracking coil. The objective lens is driven in a focusing direction and a tracking direction.

[Problem that the invention attempts to solve]

However, in conventional actuators, the focusing coil and the tracking coil are generally configured with conductive wire windings. Therefore, there is a problem that the weight of the movable parts including the objective lens and the movable member becomes heavy, and the access speed becomes slow.

As a way to solve this problem, focusing coils or tracking coils are
It has been proposed to use a printed coil in which a conductor pattern is formed into a coil shape by etching, plating, etc. on a flexible insulating sheet. These printed coils are extremely light in weight compared to coils made of conductor wire windings, so the weight of the moving parts can be reduced, allowing high-speed access, and the shape of the conductor pattern can be made into a variety of shapes. This has the advantage of increasing the degree of freedom in design.

However, when a printed coil is used, since it is formed on an insulating sheet, the thickness of the insulating sheet differs between parts where the printed coil is formed and parts where it is not formed. For this reason, for example, when a tracking coil is configured with a printed coil and a focusing coil is wound thereon with a winding wire, the thickness of the insulating sheet with the printed coil attached to the lower side is Due to the uneven winding, it is not possible to wind the focusing coil evenly without any disturbance.
There is a problem that highly accurate focusing control becomes difficult.

This invention was made by focusing on these conventional problems, and it is lightweight, which allows high-speed access, and also allows the coil to be installed uniformly, so that the objective lens can be adjusted to the desired position. It is an object of the present invention to provide an actuator that is appropriately configured so as to be able to accurately control the drive in various directions.

[Means for solving problems]

In order to achieve the above object, in this invention, among the first and second coils that are attached to the movable member that holds the objective lens partially overlapping, the inner coil is a printed coil formed on an insulating sheet. In addition, a thickness correction member is provided so that the thickness is substantially uniform at least in a portion of the insulating sheet where the coils mounted on the outside thereof overlap and where there is no printed coil.

[Effect]

In this way, if the coil located on the inside is configured with a printed coil, it can be made lighter compared to the case where it is configured with a winding, and at least in the part where the coil installed on the outside overlaps, the insulation with the printed coil can be used. If the thickness of the sheet is made almost uniform by the thickness correction member, even if another coil is to be mounted on this insulating sheet by winding, for example, it can be wound uniformly without any disturbance. can.

〔Example〕

1 to 3 show an embodiment of this invention, in which FIG. 1 is a perspective view seen from above, FIG. 2 is a perspective view seen from below, and FIG. 3 is an exploded perspective view.
The objective lens 1 is fixed to a lens holder 2A of a movable member 2 made of integrally molded plastic. In this example, the objective lens 1 is constituted by a plano-convex self-convex lens. The movable member 2 has a frame 2B having a rectangular cross section so as to surround the lens holder 2A, and a bottom wall 2C of this frame.
From this point on, the lens holder 2A stands up. Support portions 2D to 2 for supporting linear elastic support members 3A to 3D are provided on mutually opposing side walls of the frame 2B.
G is formed. One support portion 2G is not visible in FIGS. 1-3. The printed coil 4 is fixed to the outer peripheral surface of the frame 2B by adhesive. Third
In the exploded perspective view shown in the figure, the printed coil 4 is shown stretched out in one plane.

The printed coil 4 is constructed by providing four tracking coil sections 4A to 4D on a flexible insulating sheet 5, and each coil section has two layers of coils stacked on top of each other with an insulating film interposed therebetween. These coils are electrically connected to each other, and both terminals are connected to land 4E.
and is connected to the 4th floor. printed coil 4
In order to position the printed coil 4 on the outer peripheral surface of the frame 2B, a projection 2H is formed at the lower part of one side of the frame 2B, into which a recess 4G formed in the printed coil 4 is fitted. A focusing coil 6 is further wound around the outside of the insulating sheet 5 having the printed coil 4, and terminal conductors of this focusing coil 6 are connected to lands 4H and 4I provided in the margins of the insulating sheet 5 having the printed coil 4. Connect to.

As described above, in this embodiment, the tracking coil is constituted by the printed coil 4, and the focusing coil 6 is wound by winding on the insulating sheet 5 having the printed coil 4. In order to wind the coil 6 uniformly without any disturbance, dummy patterns 7A to 7F are formed on the insulating sheet 5 in the areas where the focusing coil 6 overlaps and where the tracking coil parts 4A to 4D are not present. The thickness of the insulating sheet 5 at the portion where the single coils 6 overlap is made almost uniform. Note that the dummy patterns 7A to 7F only require that the insulating sheet 5 has a substantially uniform thickness, so the dummy patterns 7A to 7F are similar to those shown in FIGS. 4A and 4B.
As shown in C and C, it may have any shape such as plate, line, or slit. These dummy patterns 7A to 7F are the tracking coil part 4.
Formed together when forming A to 4D.

In this way, if the thickness of the insulating sheet 5 in the portion where the focusing coil 6 overlaps is made almost uniform, the focusing coil 6 can be made to have a substantially uniform thickness, as shown in FIG. 6 can be wound uniformly without any disturbance. On the other hand, if a dummy pattern is not provided as shown in FIG. 5B, the focusing coil 6 will be wound irregularly and cannot be wound uniformly.

The movable member 2 is constructed as described above, and is connected to the fixed member 10 via the elastic support members 3A to 3D.

The fixing member 10 includes a base 11 made of a single piece of magnetic material. The base 11 is the bottom 11
A, and four yoke parts 11B to 11E rising vertically upward from the bottom part are integrally formed. Permanent magnets 12A and 12B are fixed to the inner surfaces of yoke parts 11B and 11C. In this example, grooves 11F and 11G are formed on the inner surfaces of these yoke parts 11B and 11C, and permanent magnets 12
After magnets A and 12B are attracted to predetermined positions of yoke parts 11B and 11C by magnetic force, adhesive is poured into the grooves 11F and 11G to fix the permanent magnets to the yoke parts. With such a configuration, the permanent magnet can be accurately positioned and fixed to the yoke portion, and assembly is also facilitated, and is particularly suitable for automatic assembly by a machine.

An insulating plate 13 and a printed circuit board 14 are attached to the outer surface of the yoke portion 11C of the base 11 with screws 15.
It sticks to the surface. A pair of protrusions 13A and 13B are provided on the inner surface of the insulating plate 13, and the yoke portion 11C is fitted and positioned between them. Further, grooves 13C to 13C into which the ends of the elastic support members 3A to 3D fit into both side surfaces of the insulating plate 13.
Grooves 14A to 1 of the same shape and size are formed at positions corresponding to the side surfaces of the printed circuit board 14 while forming the 3F.
Form 4D. As clearly shown in FIG. 2, a cylindrical protrusion 11H is formed on the bottom 11A of the base 11, and its tip is curved so that it can be rotatably attached to an optical pickup main body (not shown). Note that a part of the protrusion 11H is located on the base bottom 11A.
It is cut out together with the light path to form an optical path.

As mentioned above, in this example, the movable member 2 and the fixed member 10 are connected via the linear elastic support members 3A to 3D, and this connection state and the configuration of the elastic support members are shown in FIGS. 6A to C. . Although the elastic support member 3A is shown in these drawings, the configuration and connection state of the other elastic support members are the same. The elastic support member 3A is composed of a metal wire 3a made of phosphor bronze and having a diameter of about 0.1 to 0.2 mm, and a damper member 3b made of butyl rubber integrally formed on the outer periphery of the metal wire 3a. By using the elastic support member 3A in which the metal wire 3a and the damper member 3b are integrated in this way, the vibration energy of the metal wire is transmitted to the damper member and absorbed there, so that undesired resonance can be prevented. A damping effect can be effectively performed. In this example, the damper member 3b has a large diameter portion 3b-1 at the center and small diameter portions 3b-2 and 3b-3 at both ends.
The diameter of the large diameter portion is 1.3 mm, and the diameter of the narrow diameter portion is 0.6 mm. Further, both ends of the metal wire 3a protrude outward from the narrow diameter portions 3b-2 and 3b-3, respectively. A groove 2D-1 is formed in the support portion 2D formed on the side surface of the frame 2B of the movable member 2. As shown in FIG. 6B, this groove 2D-1
D-2 and a storage portion 2D-3 having a substantially circular cross section, and the height of the introduction portion 2D-2 is 0.5 mm, which is slightly smaller than the diameter of the narrow diameter portion 3b-2 of the damper.
The diameter of the storage portion 2D-3 is equal to the diameter of the narrow diameter portion 3b-2, which is 0.6 mm. Further, the entrance of the introduction section 2D-2 is tapered. Therefore, when fitting the narrow diameter part 3b-2 into the groove 2D-1, the narrow diameter part is pushed into the introduction part 2D-2, and while being slightly crushed, it is inserted to the storage part 2D-3. . The tip of the metal wire 3a protrudes from the support portion 2D, and is connected to the land 4H of the insulating sheet 5 having the printed coil 4 by solder 17, and the conducting wire 6a at one end of the focusing coil 6 is also connected to the land 4H. Join. In this way, by soldering the metal wires of the elastic support members 3A and 3B to the lands 4H and 4I formed in the margin of the insulating sheet 5 of the printed coil 4, the elastic support members 3A and 3B are fixed and the focuser is fixed. The single coil 6 is electrically connected to a predetermined conductor portion of the printed circuit board 14 via a metal wire.

The other end of the elastic support member 3A is inserted into grooves 13C and 14A formed in the side edges of the insulating plate 13 and the printed circuit board 14 as shown in FIG. ,14
A-1 and storage section 13C-2, 1 continuous thereto
4A-2. Introduction part 13C-1,1
The height of 4A-1 is 0.5 mm, which is slightly smaller than the diameter of 0.6 mm of the narrow diameter portion 3b-3 of the elastic support member 3A, but the diameter of the storage portions 13C-2 and 14A-2 is
The diameter is 0.8 mm, which is larger than the diameter of the narrow diameter portion 3b-3.
Therefore, when the narrow diameter portion 3b-3 of the elastic support member 3A is inserted into the storage portions 13C-2 and 14A-2 of the grooves 13C and 14A, there is a gap between the narrow diameter portion 3b-3 and the storage portion. However, this gap is filled with an adhesive 18 having viscoelastic properties. Further, the ends of the metal wires 3a protruding from the surface of the printed circuit board 14 are connected to the conductor portions 14 formed on the printed circuit board 14.
It is connected to A-3 by solder 19.

As shown in FIGS. 6A to 6C, in this example, the stepped portion 3b-4 between the large diameter portion 3b-1 of the damper member 3b of the elastic support member 3A and one of the narrow diameter portions 3b-2 is a support portion. It is separated from 2D. With this configuration, even when the elastic support member 3A is bent during operation, the stepped portion 3b-4 does not come into contact with the support portion 2D, so that undesired force is applied to the metal wire 3 via the damper member 3b.
There is no possibility that the optical axis of the objective lens will be undesirably tilted. This is particularly effective when the lengths of the damper members 3b vary. Moreover, the large diameter portion 3b-1 and the other small diameter portion 3b-
Since the stepped portion 3b-5 and the insulating plate 13 are connected to each other by the adhesive 18 as described above, the damping effect is improved. For this purpose, it is preferable to use a soft adhesive, such as a silicone-based ultraviolet curing adhesive, as the adhesive 18.

The elastic support members 3C and 3D are also attached in the same manner as described above, and their metal wires are soldered to the lands 4E and 4F to which the terminals of the printed coil 4 are connected. At the same time, the printed coil 4 is electrically connected to a predetermined conductor portion of the printed circuit board 14 via a metal wire.

FIG. 7 shows a partially exploded view of the main parts of another embodiment of this invention. In this example, objective lens 2
By sliding the movable member 22 holding the lens 1 in the axial direction with respect to the guide shaft 23 and rotating it around the guide shaft 23, the movable member 22 and therefore the objective lens 21 can be moved in the focusing direction and the tracking direction. In the rotary type actuator, the focusing coil attached to the movable member 22 is configured with a printed coil formed on an insulating sheet, and a flat winding is partially overlapped on top of the printed coil formed on an insulating sheet. A tracking coil consisting of the following is attached.

The printed coil 24 for focusing includes two focusing coils 24A and 24B formed on an insulating sheet 25. In this example, two flat tracking coils 26A, 26B, 26C, and 26D made of windings are mounted on each of the focusing coil parts 24A and 24B, and these tracking coils 26A
A dummy pattern 27 is formed on the insulating sheet 25 where the focusing coil portions 24A and 24B do not exist in the area where the focusing coil portions 26D and 26D overlap so that the thickness thereof is almost uniform.
A, 27B, 27C, 27D are formed together with focusing coil parts 24A, 24B.

In this way, tracking coils 26A to 26
The thickness of the insulating sheet 25 at the part where D is attached is
If the dummy patterns 27A to 27D are made substantially uniform, the tracking coils 26A to 26D can be installed uniformly without any difference in level and therefore without any disturbance in winding.

Note that this invention is not limited to the above-described embodiments, and can be modified or changed in many ways. For example, this invention can be effectively applied even when both the focusing coil and the tracking coil are configured with printed coils. Further, in the above-described embodiment, the thickness was corrected using a dummy pattern, but it is also possible to make the thickness substantially uniform by pasting a sticker from the outside.
Furthermore, this invention can be effectively applied not only to the four-wire system and rotation system using the four elastic support members described above, but also to conventionally known actuators using plate springs or the like.

[Effect of idea]

As mentioned above, according to this invention, the inner coil of the coils that are installed in a superimposed manner is configured with a printed coil, so the weight of the movable part can be reduced and high-speed access is possible. Not only is this possible, but the thickness of the insulating sheet with printed coils is made almost uniform at least in the area where the coils installed on the outside overlap, using a thickness correction member, so the coils overlapped on this sheet can be wound uniformly without any disorder. Therefore, the objective lens can be driven and controlled in a desired direction with high accuracy.

[Brief explanation of the drawing]

1 to 3 are perspective views showing one embodiment of this invention, FIGS. 4 A to C are plan views showing the shape of the dummy pattern, and FIGS. 5 A and B show the case with the dummy pattern. Figures 6A to 6C are cross-sectional views showing the elastic support member and its connection state, and Figure 7 is a partial view of the main part of another embodiment of this invention. FIG. 1... Objective lens, 2... Movable member, 2A...
Lens holder, 2B...Frame, 2D~2G...
...Support part, 3A to 3D...Elastic support member, 4...
Printed coil, 4A to 4D... Tracking coil section, 5... Insulating sheet, 6... Focusing coil, 7A to 7F... Dummy pattern, 10
...Fixing member, 11...Base, 11B to 11E
... Yoke part, 12A, 12B ... Permanent magnet, 1
3... Insulating plate, 14... Printed circuit board, 2
1... Objective lens, 22... Movable member, 23...
Guide shaft, 24... Print coil, 24A, 2
4B... Focusing coil section, 25... Insulating sheet, 26A to 26D... Tracking coil, 27A to 27D... Dummy pattern.

Claims (1)

[Scope of utility model registration request] a first coil that is attached to a movable member that holds an objective lens so as to partially overlap the movable member and drives the objective lens together with the movable member in a first direction parallel to the optical axis and a second direction perpendicular thereto; In the actuator including a second coil, the coil installed on the inside of the first coil and the second coil is configured with a printed coil formed on an insulating sheet, and at least the coil installed on the outside thereof is configured with a printed coil formed on an insulating sheet. An actuator characterized in that a thickness correction member is provided so that the thickness is substantially uniform in a portion of the insulating sheet where the printed coils overlap and where there is no printed coil.