JPH1064112A - Objective lens drive - Google Patents

Abstract

(57) [Problem] To fix a metal spring fixing portion to a base, a conventional objective lens driving device needs to be fixed with a screw. There is a problem that the distance changes delicately, the lens holder supported by the metal spring is tilted, the optical axis of the objective lens is tilted, and the light spot on the disk is blurred. SOLUTION: A projection is provided on a lower surface of a frame to which the other ends of a plurality of metal springs 4 supporting a lens holder holding an objective lens 1 are fixed to a base as a fixing member, and a projection is formed in a hole of the base. The parts are fitted together, and the part protruding from the hole is caulked and fixed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an objective lens driving apparatus used in an optical disk reproducing apparatus for recording and reproducing information recorded on a disk by projecting a laser beam onto the disk.

[0002]

2. Description of the Related Art In recent years, an objective lens driving device has a coil wound around a movable portion including an objective lens due to a technical tendency of reproducing not only a CD player but also an optical disk such as a CD-ROM drive at a high speed. It is considered that the moving magnet system in which a magnet is arranged in a movable portion from the moving coil system described above will become the mainstream in the future. The moving magnet system has a magnet in the movable part and a yoke and coil on the fixed side, so that the rigidity of the movable part is increased to control the high frequency range corresponding to when playing a disc at high rotation. Since there is no coil around the objective lens, there is an advantage that heat generation of the coil does not affect lens distortion.

FIG. 4 is an exploded perspective view showing a component configuration of an example of an optical pickup including a conventional objective lens driving device. 4, reference numeral 51 denotes an objective lens, 52 denotes a lens holder for holding the objective lens 51, 53a and 53b.
Is a magnet fixed to the lens holder 52;
a and 54b are metal terminals pressed into grooves formed in the lens holder 52, and 55a, 55b, 55c and 55d are 4
The book is a metal spring. Reference numeral 56 denotes a metal plate, and together with a gel holder 56 formed of a transparent resin,
It is screwed and fixed to a base 59 formed by zinc die casting. Metal springs 55a, 55b, 55c, 55d
The metal plate 56 and the metal terminal 54
The lens holder 52 is cantilevered by being soldered and fixed to each of the lenses a and b. The gel gel is gelled after the silicone gel 60 is injected into the gel holder 58, and damps the vibrations of the metal springs 55a, 55b, 55c and 55d. The bobbin 62 has an iron yoke 61
Are formed by insert molding, and a focus coil 63 and a tracking coil 64 are wound therearound. Terminal pins 65 made of four rectangular hard copper wires are press-fitted on the lower surface of the bobbin 62, and the ends of the winding start and end of the focus coil 63 and the tracking coil 64 are respectively connected to the terminal pins. It is wound.
Reference numeral 66 denotes a flexible board for making an electrical connection to the coil. The two bobbins 62 are attached and fixed to the base 59 after being attached thereto, and a total of eight terminal pins 65 of the two bobbins 62 protrude from the lower surface of the base 59, and are inserted into holes of the flexible board 66. And soldered to the land of the circuit provided there. A power supply land 66a is provided on the flexible substrate 66, and the focus coil 63 wound around the bobbin 62 and the tracking coil 64 are electrically connected to the connection land 71a of the flexible substrate 71 of the optical pickup by soldering. it can. Reference numeral 67 denotes a resin cover, which is a metal spring 55.
a, 55b, 55c, and 55d are protected.

The principle of operation is that the magnet 53 is magnetized by NS in the thickness direction, and forms a magnetic circuit with the yoke 61 facing the magnet. Since the focus coil 63 and the tracking coil 64 are wound in a direction perpendicular to the lines of magnetic force, a magnetic field is generated when energized, and a reaction is applied to the magnet to drive the lens in the focus direction and the tracking direction. .

[0005] Components of an optical pickup equipped with an objective lens driving device will also be described. 69 is a mirror,
68 is an optical base, 70 is a laser hologram unit in which a semiconductor laser, a light receiving element and a hologram element are integrated, 72 is a metal heat sink attached to the back of the laser hologram unit, and 73 is a laser hologram unit 70 Are fixed to the optical base 68, and screws 74a and 74b are screwed into the screw holes provided in the base 59 to adjust the inclination of the entire objective lens driving device including the objective lens 51. It is. In addition, 75
A spring 76 for slidably pressing the base 59 against the optical base 68 and a fixing screw 76 are provided.

[0006]

However, in the above-described objective lens driving device, it is necessary to fix the metal spring fixing portion to the base with a screw. As a result, there is a slight change between the metal spring fixing part and the base due to aging and a severe use environment, and as a result, the lens holder supported by the metal spring is tilted, and the optical axis of the objective lens is tilted and the disk is tilted. Has the problem that the light spot is blurred, and requires space in the thickness direction and the plane direction to screw the metal spring fixing portion and the base, which is disadvantageous in reducing the thickness and size. There was a problem that.

SUMMARY OF THE INVENTION In view of the above-mentioned conventional problems, the present invention provides a method for fixing a metal spring fixing portion and a base by fitting a projection of a frame for fixing a metal spring into a hole of the base and fixing the projection by welding. Cost and man-hours,
By simplifying assembly, productivity can be improved, and between the metal spring fixing part and the base is firmly fixed. It is an object of the present invention to provide an objective lens driving device that enables stable characteristics to be maintained without generating a lens and realizes a minimum necessary fixing space by not using a screw.

[0008]

SUMMARY OF THE INVENTION In order to solve this problem, an objective lens driving apparatus according to the present invention comprises an objective lens, a lens holder for holding the objective lens, a magnet fixed to the lens holder, and a lens. A plurality of metal springs for supporting the holder, a frame for fixing the other end of the metal spring, a yoke made of a magnetic material arranged to face the magnet, two coils wound around the yoke, A base as a member is provided, and a protrusion is provided on the lower surface of the frame for positioning and fixing with the base,
The projection is fitted into the hole of the base, and a portion protruding from the hole is caulked and fixed.

Thus, by fitting the projection of the frame for fixing the metal spring into the hole of the base and fixing it by caulking, the cost and man-hour for fixing the metal spring fixing portion and the base are reduced, and the assembly is simplified. By simplifying it, it is possible to improve productivity.Also, by firmly fixing the metal spring fixing part and the base, and suppressing the change over time and the inclination of the lens holder due to severe use environment,
It is possible to obtain an objective lens driving device that enables stable characteristics to be maintained without causing optical axis deviation, realizes a minimum required fixing space, and enables a reduction in thickness and size.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION
An objective lens, a lens holder for holding the objective lens, a magnet fixed to the lens holder, a plurality of metal springs for supporting the lens holder, a frame for fixing the other end of the metal spring, and the magnet. A yoke, which is a magnetic material disposed opposite to the yoke, two coils wound around the yoke, and a base, which is a fixed-side member, and a projection is provided on the lower surface of the frame for positioning and fixing with the base, The objective lens driving device is characterized in that the projection is fitted into the hole of the base and a portion protruding from the hole is caulked and fixed, and the metal spring fixing portion and the base are firmly fixed, It has the function of realizing the minimum necessary fixing space and improving the assembling property.

According to a second aspect of the present invention, there is provided the objective lens driving device according to the first aspect, wherein the caulking is fixed by ultrasonic welding. Has the effect of fixing without affecting.

According to a third aspect of the present invention, there is provided an objective lens driving device according to the first or second aspect, wherein at least three projections are provided so as to support the weight of the frame substantially evenly. This has the effect of fixing the contact surface of the metal spring fixing portion and the base main plane without rotation or play in the planar direction.

According to a fourth aspect of the present invention, one of the at least three projections provided on the frame is provided on a lower surface of a substantially central portion of the metal spring fixing wall. The objective lens driving device according to any one of items 1 to 3, has an effect of preventing deformation of the metal spring fixing wall when fixed to the base.

According to a fifth aspect of the present invention, at least three protrusions provided on the frame are not provided on the lower surface of the metal spring fixing wall or in the vicinity thereof. The objective lens driving device described above has an effect of minimizing the influence on a metal spring when fixed to a base.

According to a sixth aspect of the present invention, the objective lens according to any one of the first to fifth aspects, wherein only the narrow portion near the projection provided on the frame comes into contact with the base. This is a driving device, and has an effect that rattling does not occur after the metal spring fixing portion is fixed to the base.

According to a seventh aspect of the present invention, the crimp-stopping portion at the tip of the projecting portion of the frame is narrowed near the periphery of the hole on the back surface side of the surface of the base contacting the frame so as not to protrude from the main surface on the back surface side of the base. 7. The objective lens driving device according to claim 1, wherein a concave portion is provided in the portion, and the caulking fixed portion does not hinder the optical path inside the optical pickup and is thin. This has the effect of not hindering the design of the product.

According to an eighth aspect of the present invention, there is provided the objective lens driving device according to the seventh aspect, wherein the planar shape of the recess is substantially triangular or substantially square. By contacting the side,
This has the effect of eliminating rattling in the plane direction.

An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is an exploded perspective view showing a component configuration of an optical pickup including an objective lens driving device according to a first embodiment of the present invention. In FIG. 1, 1
Is an objective lens, 2 is a lens holder that holds the objective lens 1, 4a, 4b, 4c, and 4d are four metal springs, 5 is a frame that holds these four metal springs, In order to support the weight of the frame 5 almost equally, three projections 5a, 5
b, 5c (5b, 5c are not shown because they are not visible), and one of the protrusions 5a is located on the lower surface of the substantially central portion of the metal spring fixing wall. Here, the lens holder 2, the frame 5, and the four metal springs 4a, 4b, 4
c and 4d can be obtained as an integral product from the same mold by insert molding this metal spring. In this state, the lens holder 2 is cantilevered by the four metal springs 4a, 4b, 4c, and 4d. Reference numerals 3a and 3b denote magnets that are adhered and fixed to the lens holder 2. Further, an iron yoke 6a is insert-molded on the bobbin 7a, and a focus coil 8a and a tracking coil 9a are wound therearound. . Four grooves are formed on both ends of the upper surface of the bobbin 7a, and the focus coil 8a
The winding start and end terminals of the tracking coil 9a are wound around the respective grooves. The two bobbins 7a, 7b are fixedly bonded to the frame 5. Reference numeral 10 denotes a gel holder, which is formed in a box shape by the frame 5 and the bobbin 7b, and gels the gel 11 after injecting the gel 11 into the container. Reference numeral 12 denotes a base formed of sheet metal, which has positioning holes 12a, 12b, and 12c for fitting with the projections 5a, 5b, and 5c of the frame 5, and the frame 5 is fixed to the base 12 by caulking. When the frame 5 and the base 12 are in contact with each other, a substantially rectangular concave portion is formed on the rear surface of the contact surface between the frame 5 and the base 12 so that the projections 5a, 5b, and 5c do not protrude from the rear main surface of the surface where the frame 5 contacts the base 12. Is provided.

FIG. 2 is a partial side cross-sectional view when the frame 5 and the base 12 are caulked and fixed. FIG.
3 is a bottom view of FIG. The frame 5 and the base 12 are connected to the holes 12a, 12b, 12c of the frame 12 as shown in FIG.
Abuts only in the narrow part around the vicinity. The protrusions 5a, 5b, 5c of the frame 5 are connected to the holes 12a, 1
2b and 12c, and are fixed by caulking by ultrasonic welding on the back side of the contact portion of the base 12, and the flesh of the projections 5a, 5b and 5c of the frame 5 deformed by this caulking is Due to the concave portion provided on the rear surface side of the contact portion, it does not protrude from the main surface 12d on the rear surface side of the contact portion, and since it is a substantially rectangular concave portion, the protrusion portions 5a, 5b, 5
The deformed portion due to the caulking fixation of c partially contacts the side surface of the concave portion.

Reference numeral 13 denotes a flexible substrate for making electrical connection to the coil, and is covered so as to cover the entire frame.

The components of the optical pickup equipped with the objective lens driving device will also be described. 16 is a mirror,
Reference numeral 15 denotes an optical base, 17 denotes a laser hologram unit in which a semiconductor laser, a light receiving element and a hologram element are integrated, 19 denotes a metal heat sink attached to the back of the laser hologram unit, and 18 denotes a flexible optical pickup. The substrate 20 is a screw for fitting the laser hologram unit 17 to the optical base 15 and adjusting the inclination of the entire objective lens driving device including the objective lens 1. Further, 22 is a spring for slidably pressing the base 12 against the optical base 15, and 23 is a fixing screw thereof.

The operation of the objective lens driving device configured as described above will be described below.

In FIG. 1, magnets 3a and 3b are
NS is magnetized in the thickness direction, and forms a magnetic circuit with the opposed yokes 6a and 6b. Focus coil 8
Since a and 8b and the tracking coils 9a and 9b are wound in a direction perpendicular to the lines of magnetic force, a magnetic field is generated by energizing, and the reaction of the force is applied to the magnet. Further, the holder 2 has four metal wires 4a, 4
Since the cantilever is supported by b, 4c, and 4d, the objective lens 1 and the holder 2 can be driven in the focus direction and the tracking direction by the reaction of this force.

As described above, according to the present embodiment, the projections 5a, 5b, 5c provided on the frame 5 are
By fitting into the holes 12a, 12b, and 12c provided in the base 2 and caulking and fixing the base 12 at the back side of the contact portion,
At the same time as firmly fixing, a minimum necessary fixing space can be realized, and the fixing can be performed without using a screw which is necessary for fixing in the past. This makes it possible to reduce costs, reduce the number of steps for fixing screws, improve assemblability, and increase productivity.

By performing the caulking and fixing by ultrasonic welding, the fixing can be performed quickly and the manufacturing time can be shortened. Furthermore, since the three projections 5a, 5b, and 5c are caulked and fixed to the base 12, a flat surface is formed by three points, so that rotation or flat direction rattling that can occur when fixing one or two points is eliminated. Is possible,
In the operation of the lens holder 2, it is possible to eliminate the vibration to the contact portion due to the reaction force to the metal spring fixing portion.
As a result, the lens holder 2 is not affected by the fixing portion, the inclination of the lens holder 2 is suppressed, and the lens holder 2 can be driven without causing an optical axis shift of the objective lens. Further, the lower surface of the metal spring fixing wall 5d has only the protrusion 5a substantially at the center, so that the base 12
It is possible to prevent the deformation of the metal spring fixing wall 5d when the metal spring is fixed. As a result, there is no distortion of the metal springs 4a, 4b, 4c and 4d when the lens holder 2 is fixed.
Of the optical axis of the objective lens can be prevented in actual operation. Even when there is no protrusion near the lower surface of the metal spring fixing wall, the same effect can be obtained because the metal spring fixing wall 5d is not deformed. Furthermore, since the base 12 and the frame 5 are in contact with the base 12 only in the narrow portions near the protrusions 5a, 5b, and 5c, there is no play in the vertical direction due to the warpage or the plane roughness of the base 12 or the frame 5. Therefore, vibration to the metal spring fixing wall 5d can be eliminated, and when the lens holder 2 is operated, the metal spring 4
Since no extra vibration is applied to a, 4b, 4c, and 4d, stable characteristics can be obtained. Further, by providing a concave portion in the caulking fixing portion of the base 12, the flesh of the caulking fixing portion at the tip of the protruding portion 5a, 5b, 5c of the frame 5 does not protrude from the main plane 12d on the back surface side of the contact portion of the base 12. Because it does not hinder the optical path, it not only prevents light scattering and obtains stable characteristics, but also enables a thinner and smaller design, affecting the slidability of the objective lens driving device. Absent. Further, since the planar shape of the concave portion provided on the base 12 is substantially rectangular, the base 12 is positioned from the center of the projections 5a, 5b, 5c of the frame 5.
There is a difference in distance to the concave side surface 12e. This allows
The protrusions 5a, 5b, 5c of the frame 5 are fixed by caulking.
Are spread in the planar direction in the recess, and the protrusions 5 of the frame 5
a, 5b, and 5c are in contact with the side surface 12e of the concave portion closest to the center. Since the fixing in the horizontal direction is added to the fixing in the vertical direction with respect to the base 12, the fixing force is increased, the rattling in the vertical direction and vibration are suppressed, and the rattling in the planar direction is completely eliminated. . This is not greatly affected by the state of deformation of the distal end of the frame 5 at the time of caulking and fixing the projections 5a, 5b, 5c, and eliminates rattling in the planar direction. Therefore, there is no influence on the metal spring fixing wall 5d, and the operation of the lens holder is not affected. The shape of the concave portion is substantially polygonal, and as the number of corners increases, the shape gradually approaches a circle, and the protrusions 5a, 5b,
The distance from the center of 5c to the concave side surface 12e of the base 12 no longer varies, and the same effect cannot be obtained by deformation by caulking.

[0026]

As described above, according to the present invention, the cost of fixing the metal spring fixing portion and the base is secured by fitting the protrusion of the frame for fixing the metal spring into the hole of the base and fixing the base by caulking. In addition to reducing man-hours and simplifying assembly, productivity has been improved, and the metal spring fixing part and base have been firmly fixed, preventing the lens holder from tilting due to aging and severe use environments. By doing so, it is possible to maintain stable characteristics without causing optical axis shift, to achieve a minimum required fixing space, and to obtain an advantageous effect of enabling reduction in thickness and size.

Further, by caulking and fixing by ultrasonic welding, the manufacturing time can be shortened.

Further, since the base is fixed by caulking with at least three projections, a plane is formed by three points, so that the rotation and the play in the plane direction can be eliminated, and a further effect can be obtained.

Further, since there is only one projection at the center on the lower surface of the metal spring fixing wall, it is possible to prevent the deformation of the metal spring fixing wall when fixed to the base.
In the actual operation, it is possible to prevent the optical axis of the objective lens from being shifted. In addition, even when there is no protrusion near the lower surface of the metal spring fixing wall, the same effect can be obtained.

Further, since the base is abutted only at the narrow portion near the projection, it is possible to eliminate the backlash in the vertical direction and not to apply extra vibration to the metal spring, so that stable characteristics can be obtained. It is possible to obtain.

Further, by providing a concave portion in the caulked fixing portion on the base, the flesh of the caulked fixing portion does not protrude from the main plane on the back surface side of the abutting portion of the base and does not hinder the optical path. And a thinner and smaller design is possible. In addition, since the concave portion provided in the base is substantially triangular or substantially rectangular, the caulked and fixed meat abuts against the side surface of the concave portion. There is no effect on the fixed part.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing a component configuration of an optical pickup including an objective lens driving device according to an embodiment of the present invention.

FIG. 2 is a side sectional view when the frame and the base of the objective lens driving device according to the embodiment of the present invention are fixed.

FIG. 3 is a bottom view when the frame and the base of the objective lens driving device according to the embodiment of the present invention are fixed.

FIG. 4 is an exploded perspective view showing a component configuration of an optical pickup including a conventional objective lens driving device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Objective lens 2 Holder 3 Magnet 4 Metal spring 5 Frame 6 Yoke 7 Bobbin 8 Focus coil 9 Tracking coil 10 Gel holder 11 Gel 12 Base 13 Flexible substrate 15 Optical base 16 Mirror 17 Laser hologram unit 18 Optical pickup flexible substrate 19 Heat radiation Plate 20 Fixing spring 21 Adjusting screw 22 Spring 23 Fixing screw

Continuing from the front page (72) Inventor Daisaburo Kubota 1006 Kadoma Kadoma, Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd.

Claims (8)

[Claims] 1. An objective lens, a lens holder for holding the objective lens, a magnet fixed to the lens holder, a plurality of metal springs for supporting the lens holder, and a frame for fixing the other end of the metal spring. And a yoke made of a magnetic material disposed opposite the magnet, two coils wound around the yoke, and a base serving as a fixed-side member, and a projection for positioning and fixing to the base on the lower surface of the frame. An objective lens driving device, wherein a portion is provided, the projection is fitted into the hole of the base, and a portion protruding from the hole is caulked and fixed. 2. The objective lens driving device according to claim 1, wherein the caulking is fixed by ultrasonic welding. 3. The objective lens driving device according to claim 1, wherein at least three projections are provided so as to support the weight of the frame substantially evenly. 4. At least 3 provided on the frame
The one projection of one projection is provided in the lower surface of the substantially central part of the metal spring fixing wall.
The objective lens driving device according to any one of claims 1 to 3. 5. At least 3 provided on said frame
4. The method according to claim 1, wherein the two protrusions are not provided on the lower surface of the metal spring fixing wall or in the vicinity thereof.
Item 4. The objective lens driving device according to Item 1. 6. The objective lens driving device according to claim 1, wherein only a narrow portion near a projection provided on the frame comes into contact with the base. 7. A concave portion is provided in a narrow portion near the periphery of a hole on the back surface side of the surface of the base that abuts on the previous frame so that the crimp-stopping portion at the tip of the projection of the frame does not protrude from the main surface on the rear surface side of the base. The objective lens driving device according to any one of claims 1 to 6, wherein: 8. The objective lens driving device according to claim 7, wherein the planar shape of the concave portion is substantially triangular or substantially quadrangular.