JPH103676A - Optical pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To especially enhance the positional accuracy of an objective lens at the time of tracking and also to improve the responsiveness of the objective lens in a biaxial actuator. SOLUTION: The moving member of a biaxial actuator 3 is divided into a focusing member 9 which is freely movably supported in a direction vertical to the signal recording surface of an optical disk and a tracking member 10 which support an objective lens 4 and which is freely rotatably supported to the focusing member 9. Simultaneously, the tip part of the supporting member 18 fixingly provided to the focusing member 9 is formed to be a pointed end shape and a conically recessed part 24 is formed on the end face of a member to be supported 23 provided on the tracking member 10 and the pointed end part of the supporting member 18 is brought into point contact with the recessed part of the member to be supported 23 by being inserted into the recessed part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pickup device. More specifically, the present invention relates to a technique for improving the position accuracy of an objective lens during tracking, and improving tracking responsiveness, particularly in a biaxial actuator of an optical pickup device.

[0002]

2. Description of the Related Art FIG. 5 shows an example of a conventional optical pickup device a.

An optical pickup device a has an objective lens b
A two-axis actuator c for moving the lens in the focusing direction and the tracking direction.

The two-axis actuator c includes a base substrate d
And a magnetic field forming portion e attached to the base substrate d and an objective lens b, and are rotatable with respect to the base substrate d and slidable in the axial direction with respect to the rotation axis. It has a lens holding member f as a supported movable member.

The base substrate d is fixed to a member (not shown) which is moved in the radial direction with respect to the optical disk g, and a front end portion of the base substrate d (a leftward direction in FIG. The direction is set to the rear.), The support shaft h is fixed upward.

The yoke i is made of a magnetic material which is bent in a U-shape and arranged in a direction opening upward, and a permanent magnet j adhered to the inner surface of the front wall of the yoke i. The lower portion of the yoke i is fixed to the rear end of the base substrate d by appropriate means.

The lens holding member f has an objective lens b held at its front end and a support hole k through which a support shaft h fixed to a base substrate d is inserted. ing.

At the rear end of the lens holding member f, a focusing coil 1 for moving the objective lens b in a direction perpendicular to the optical disc g (hereinafter referred to as a "focusing direction") and a radial direction of the optical disc g. And a tracking coil m for rotating in a direction parallel to (hereinafter, referred to as a “tracking direction”).

The supporting shaft h of the base substrate d is inserted into the supported hole k of the lens holding member f, and a part of the focusing coil l and the tracking coil m are connected to the permanent magnet j of the magnetic field forming part e. And a rear wall of the yoke i opposed thereto.

In such a lens holding member f, a spring member n is provided between the lens holding member f and the base substrate d, and when no current flows through the focusing coil l and the tracking coil m, the objective lens b Are located at respective predetermined positions in the focusing direction and the tracking direction (hereinafter, referred to as “neutral points”).

In the optical pickup device a, when an electric current is applied to the focusing coil l, the lens holding member f is guided by the support shaft h whose supported hole k is fixed to the base substrate d. The objective lens b is moved in the focusing direction by being slid up and down.

When a current is applied to the tracking coil m, the lens holding member f is moved from the supporting hole k to the base substrate d.
The objective lens b is moved in the tracking direction by being rotated in the horizontal direction around the support shaft h fixed to the objective lens b.

When the supply of the current to the focusing coil 1 and the tracking coil m is stopped, the objective lens b returns to the neutral point again by the elastic force of the spring member n. I have.

[0014]

However, in the conventional optical pickup device a, a support shaft h fixed to the base substrate d is inserted into a supported hole k provided in the lens holding member f, and the support shaft h is fixed. h is used as a reference for movement in the focusing direction and as a center of rotation in the tracking direction.
A clearance was required between the support hole k and the support hole k to allow sliding and rotation. Therefore, the clearance rattles the lens holding member f in the horizontal direction and shifts the center of rotation in the tracking direction, so that there is a problem that the accuracy of movement of the objective lens b in the tracking direction cannot be increased.

Further, since the objective lens b, the focusing coil 1 and the tracking coil m are mounted on one lens holding member f as a movable member, the objective lens b can be used for both focusing and tracking. In addition, the focusing coil 1 and the tracking coil m must always be moved together with the lens holding member f, and in particular, there is a problem that the responsiveness during tracking is lacking.

[0016]

In order to solve the above-mentioned problems, the optical pickup device of the present invention has a movable member of a biaxial actuator supported movably in a direction perpendicular to a signal recording surface of an optical disk. A focusing member,
The objective lens is supported and divided into a tracking member rotatably supported with respect to the focusing member, and the focusing member and the tracking member are elastically supported with respect to the base or the focusing member, respectively. The tracking member is supported on the focusing member by point contact.

Therefore, according to the optical pickup device of the present invention, the lens holding member as the movable member is divided into the tracking member and the focusing member, and the tracking member is supported by the point contact with the focusing member. The position where the point contact is made becomes the center of rotation of the tracking member, and the center of rotation does not shake, so that the accuracy of movement of the objective lens in the tracking direction can be improved.

Also, since the focusing member and the tracking member are divided, only the tracking member needs to be rotated at the time of tracking, that is, it is not necessary to move the focusing coil provided on the focusing member. Can be made extremely responsive.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the optical pickup device of the present invention will be described below with reference to an illustrated embodiment.

FIGS. 1 to 4 show an embodiment of the optical pickup device 1 of the present invention.

The optical pickup device 1 includes a base 2, a biaxial actuator 3 provided above the base 2, an objective lens 4 supported by the biaxial actuator 3, and a lower side of the base 2. And a pickup unit 5 provided in the control unit. Such an optical pickup device 1 is provided on the side of the optical disk 6 facing the signal recording surface 7 (in the present embodiment, on the lower surface side of the optical disk 6).

The base 2 is movably supported by a feed mechanism (not shown) so that the objective lens 4 moves in the radial direction of the optical disk 6.

The biaxial actuator 3 includes a rectangular base substrate 8 fixed to the upper surface of the base 2 and a front-rear direction (the leftward direction in FIG. , The direction toward the right is the rear.)
And a plate-like focusing member 9 whose length is shorter than the width of the base substrate 8 and which is disposed above the focusing member 9, and is longer than the focusing member 9 and narrower than the focusing member 9. A flat plate-like tracking member 10, a magnetic field forming portion 11 arranged at a position close to the rear end of the base substrate 8, and a focusing member attached to the focusing member 9 and cooperating with the magnetic field forming portion 11. A focusing coil 12 for moving the tracking member 9; a tracking coil 13 attached to the tracking member 10 for moving the tracking member 9 in cooperation with the magnetic field forming unit 11; And an elastic member 14 for resiliently supporting the member.

A support shaft 15 is provided upright at the front end of the base substrate 8, and the tip of the support shaft 15 extends above the tracking member 10.

At the front end of the focusing member 9 at a position corresponding to the support shaft 15, a supported hole 16 is formed, and the upper and lower opening edges of the supported hole 16 are directed upward and downward. Protruding guide cylinders 17 are provided respectively.

Then, the support shaft 15 of the base substrate 8 is inserted into the supported hole 16 of the focusing member 9 and the guide cylinders 17, 17, whereby the focusing member 9 is vertically movable with respect to the base substrate 8. And the posture of the focusing member 9 with respect to the base substrate 8 does not tilt.

The above-described guide cylinder 1 of the focusing member 9
A fulcrum member 18 having a sharp tip protrudes upward at a position closer to the rear than 7, 17 and has support pieces 19, 1 on both left and right edges with the fulcrum member 18 interposed therebetween.
9 are protruded upward, and these support pieces 19, 19
Are provided with screw holes 19a on the upper surface.

A relatively large rectangular coil mounting hole 20 penetrating in the vertical direction is formed at the rear end of the focusing member 9, and a rectangular shape is formed along the inner peripheral surface of the coil mounting hole 20. The wound focusing coil 12 is adhered.

A lens mounting hole 21 for mounting the objective lens 4 is formed in a portion of the tracking member 10 which protrudes forward from the focusing member 9, and is located slightly behind the lens mounting hole 21. At a position corresponding to the guide cylinder 17 of the focusing member 9, an opening 22 larger than the outer diameter of the guide cylinder 17 is formed.

The upper guide cylinder 17 is inserted into the opening 22 with a margin, so that the focusing member 9 and the tracking member 10 do not interfere with each other.

A fulcrum member 23 is planted at a position slightly behind the opening 22 of the tracking member 10 and above the fulcrum member 18 protruding from the focusing member 9. The lower end of the fulcrum member 23 projects slightly from the lower surface of the tracking member 10.

The fulcrum member 23 has a conical concave portion 24 at the lower end surface, and a portion (hereinafter, referred to as a "skew adjustment pin") 25 having a smaller diameter at the upper end portion than other portions. ing.

Then, the tip of the upper end of the fulcrum member 18 is inserted into the recess 24 of the fulcrum member 23, and the tip makes point contact with the apex of the recess of the recess 24, whereby the tracking member 10 is moved to the focusing member. 9 is supported without play in the horizontal direction.

Further, as described above, the tracking member 10
When the fulcrum member 23 and the fulcrum member 18 are in point contact with each other, the base end of the skew adjustment pin 25 is
Or the base end of the skew adjustment pin 25 is slightly higher in the vertical direction than the upper end surface of the skew adjustment pin 25.

An opening 26 having a convex shape when viewed from above is formed at a position close to the rear end of the tracking member 10 in such a direction that the convex side is located on the front side. Part of the magnetic field forming part 11 is positioned to penetrate the part.

On the rear end face of the tracking member 10, two tracking coils 1 wound in a rectangular shape as viewed from the rear.
3 and 13 are attached in a state where they are arranged side by side.

The focusing coil 12 and the tracking coils 13 and 13 are electrically connected to a predetermined printed circuit board by a flexible printed circuit board or a lead wire (not shown).

The magnetic field forming part 11 includes a yoke 27 having a U-shape as viewed from the left and right, and a front yoke piece 28 of the yoke 27.
Permanent magnet 29 attached to the inner surface of the
And a sub-yoke 31 having a convex shape with a slightly narrower front half as viewed from above, which is provided between the upper ends of the front yoke piece 28 and the rear yoke piece 30.

The yoke 27 is fixed at a position closer to the rear of the base substrate 8. A notch 28 a is formed at the upper end of the front yoke piece 28, and the upper yoke 27 protrudes upward at the upper end of the rear yoke piece 30. A projection 30a is formed.

The fitting hole 3 is located slightly forward of the rear end wall 32 which is integrally provided from the rear side edge of the sub-yoke 31 and corresponds to the projection 30a of the rear yoke piece 30 of the yoke 27.
3 is formed, and a screw hole 34 penetrating vertically is formed at the front end thereof.

A position restricting screw 35 is screwed into the screw hole 34 from above. The position restricting screw 35 penetrates through the sub-yoke 31, and the lower end of the screw passes through the opening 26 of the tracking member 10 and approaches the focusing member 9. Is located.

The magnetic field forming section 11 is configured such that the front yoke piece 28 and the permanent magnet 29 pass through the inside of the focusing coil 12 attached to the focusing member 9 and the inside of the opening 26 at the rear end of the tracking member 10. It protrudes above the tracking member 10.

The sub-yoke 31 has a narrow front side portion fitted into the notch 28a of the front yoke piece 28 of the yoke 27, and a projection of the rear yoke piece 30 into the fitting hole 33 at the rear end. The rear end wall 32 of the sub-yoke 31 is fixed to the rear yoke piece 30 of the yoke 27 by screws, so that the sub-yoke 31 is attached to the upper end of the yoke 27.

Thus, the permanent magnet 29 and the front yoke piece 2
8-Rear yoke piece 30-Magnetic circuit called gap between rear yoke piece 30 and permanent magnet 29; permanent magnet 29-Front yoke piece 28-Subyoke 31-Rear yoke piece 30-Rear yoke piece 30 and permanent magnet 29 Is formed, and a part of the focusing coil 12 and the tracking coils 13, 13 are located in the gap between the permanent magnet 29 and the rear yoke piece 30.

The elastic member 14 mainly includes a first elastic portion 36 for elastically supporting the focusing member 9 vertically and a second elastic portion 37 for mainly elastically supporting the tracking member 10 horizontally. Become.

The first elastic portion 36 has a plate-shaped main portion 38 which is long in the left-right direction, and upper and lower elastic pieces which protrude rearward from both left and right ends of the main portion 38 and are displaced downward toward the rear. In the center of the main portion 38, the support shaft 15 of the base substrate 8 and the guide cylinder 17 of the focusing member 9 are positioned in a penetrating manner, and an insertion hole 40 is formed.

The first elastic portion 36 is formed such that the main portion 38 is attached to the lower surface of the focusing member 9 by appropriate means such as caulking in a state where the lower guide cylinder 17 of the focusing member 9 is inserted through the insertion hole 40. The rear ends of the upper and lower elastic pieces 39 are fixed to the rear left and right ends of the base substrate 8 by appropriate means. This allows
The magnetic field forming portion 1 is provided between the two upper and lower elastic pieces 39 and 39.
The focusing member 9 is elastically supported in the up-down direction with respect to the base substrate 8. The upper and lower elastic pieces 39, 39 are slightly curved as shown in FIGS. 1, 3, and 4, and the base substrate 8 of the focusing member 9 is formed.
Is allowed to move vertically.

The second elastic portion 37 is formed of two plate-like connecting pieces 41, 41 protruding forward from two places near the center of the front side edge of the main portion 38 of the first elastic portion 36. A right and left elastic piece 4 having a J-shape or an inverted J-shape as viewed from the front is provided at the front end of each of the connecting pieces 41, 41 and at the side edge facing outward.
The left and right elastic pieces 42, 42 'are connected to the connecting pieces 41, 41 at the upper ends of the shorter vertical portions.

The second elastic portion 37 is fixed such that the upper ends of the long vertical portions 42a, 42a 'of the left and right elastic pieces 42, 42' are held on the front end of the tracking member 10 from both right and left sides. Thereby, the tracking member 10 is resiliently supported in the left-right direction with respect to the focusing member 9 at the front end thereof, and the tracking member 10 is connected to the connecting portion between the left and right elastic pieces 42 and 42 ′, and It is supported by the focusing member 9 at three points of the point contact portion between the fulcrum member 23 and the fulcrum member 18.

The first elastic portion 36 and the second elastic portion 37 are formed integrally by punching and bending a plate-like member into a predetermined shape.

A skew adjusting piece 43 made of a plate-like member is provided between the tips of the supporting pieces 19 of the focusing member 9.
The skew adjustment piece 43 has a pin receiving hole 44 at the center thereof, and screw insertion holes 4 at both ends thereof.
5 and 45 are respectively formed.

The inner diameter of the pin receiving hole 44 is formed slightly larger than the diameter of the skew adjusting pin 25, and a plurality of pin receiving pieces 46, 46,. It is formed toward.

The screw insertion holes 45, 45 are
The small screws 47, which are screwed into the screw holes 19a, 19a formed in the upper end surfaces of the small screws 9, 19, are formed so as to be larger than the shaft diameter and slightly smaller than the head. The centers of 47 and 47 and the centers of screw insertion holes 45 and 45 can be made eccentric.

When the skew adjusting pin 25 is fitted into the pin receiving hole 44 from below, the skew adjusting piece 43 is inserted into the screw insertion holes 45 from above.
7 and 47 are inserted, and the small screws 47 and 47 are attached to the focusing member 9 by screwing into the screw holes 19a and 19a of the support pieces 19 and 19.

At this time, the peripheral edge of the pin receiving hole 44 of the skew adjustment piece 43 is elastically contacted with the stepped portion above the fulcrum member 23 and between the base end of the skew adjustment pin 25 and thereby. Thus, the point contact portion between the fulcrum member 18 and the fulcrum member 23 comes into elastic contact.

The skew adjusting pin 25 is resiliently sandwiched by pin receiving pieces 46, 46,... Formed in a pin receiving hole 44 of the skew adjusting piece 43.

Then, with the small screws 47, 47 slightly loosened, the skew adjustment piece 43 is
By moving the tracking member 10 in the front, rear, left, and right directions, the posture of the tracking member 10 with respect to the focusing member 9, that is, the skew adjustment can be performed.

That is, the skew adjustment piece 43 is
19, the skew adjustment pin 25, that is, the inclination of the fulcrum member 23 with respect to the focusing member 9 can be changed.
Can be matched with the axis of the fulcrum member 18, and skew adjustment can be performed.

When the skew adjustment is performed,
Although the skew adjustment pin 25 may be inclined with respect to the skew adjustment piece 43, as described above, the skew adjustment piece 4
3 pin receiving pieces 46, 46,.
Since the skew adjustment pin 25 is resiliently supported by ・, the skew adjustment pin 25 can be reliably held.

The pickup section 5 includes a semiconductor laser 49 that oscillates a laser beam 48 and a collimating lens 50 that converts the laser beam 48 emitted by the semiconductor laser 49 into parallel light.
And a reflecting mirror 51 disposed in front of the collimating lens 50 and reflecting the laser light 48 upward. The reflecting mirror 51 is located below the laser passage hole 52 of the base 2 and It is arranged below.

The laser beam 48 emitted from the semiconductor laser 49 passes through the collimating lens 50 and is reflected upward by the reflecting mirror 51, and the signal of the optical disk 6 is reflected by the objective lens 4 held by the tracking member 10. The light is focused on the recording surface 7.

The laser light (return light) 48 reflected by the signal recording surface 7 of the optical disk 6 is
The light passes through the laser passage hole 52 and the reflecting mirror 51, is separated by a beam splitter (not shown), is received by a detector (not shown), and is converted into an electric signal.

Thus, the optical pickup device 1 of the present invention
In this case, a current is applied to the focusing coil 12 attached to the focusing member 9 to move the focusing member 9 in the vertical direction (the direction of the arrow shown in FIG. 3) along the support shaft 15, whereby the focusing is performed. The objective lens 4 together with the tracking member 10 supported by the member 9
Is moved in the focusing direction. The magnetic field forming unit 1
The tip of the position regulating screw 35 attached to the first sub-yoke 31 projects below the lower surface of the tracking member 10 and regulates the upward movement range of the focusing member 9, so that the upper and lower elastic pieces 39, 39 are provided. Are not bent beyond the elastic limit. Further, the tip of the position regulating screw 35 comes into contact with the focusing member 9 when it comes into contact with the tracking member 10.
This is because the tracking member 10 is inclined with respect to the focusing member 9 and the optical axis of the objective lens 4 is shifted.

When a current is applied to the tracking coils 13 attached to the tracking member 10, the tracking member 10 is moved to the fulcrum member 18 of the focusing member 9.
Is rotated in the horizontal direction (in the direction of the arrow shown in FIG. 2) around the center of rotation, whereby the objective lens 4 is moved in the tracking direction. Further, since the fulcrum member 18 of the focusing member 9 is in point contact with the concave portion 24 of the fulcrum member 23,
There is no clearance between 8 and 23, so that the center of rotation of the tracking member 10 is not eccentric.

Therefore, in the biaxial actuator 3 of the optical pickup device 1 of the present invention, the portions serving as the rotation fulcrums 18 and 23 for rotating the objective lens 4 in the tracking direction are formed by point contact. , Pivot point 1
Rotation accuracy can be improved without rattling at 8, 23.

Further, since the lens holding member as the movable member is divided into the tracking member 10 and the focusing member 9, in particular, only the tracking coils 13 necessary for tracking are mounted on the tracking member 10, so that the conventional device is provided. Since there is no extra component such as the focusing coil 12, the weight of the movable member during tracking can be reduced, and the responsiveness of tracking can be improved.

[0067]

As is apparent from the above description, the optical pickup device of the present invention is a focusing member in which the movable member of the biaxial actuator is movably supported in a direction perpendicular to the signal recording surface of the optical disk. And a tracking member that supports the objective lens and that is rotatably supported with respect to the focusing member. The focusing member and the tracking member are resiliently supported on the base or the focusing member, respectively. At the same time, the tracking member is supported on the focusing member by point contact, so that the position where the point contact is made becomes the center of rotation of the tracking member, and the center of rotation does not shake. The movement accuracy in the tracking direction can be improved.

Since the movable member of the biaxial actuator is divided into a focusing member and a tracking member, only the tracking member needs to be rotated during tracking, that is, it is necessary to move a focusing coil provided on the focusing member. Therefore, tracking responsiveness can be extremely improved.

In the above embodiment, the tracking member is supported by the focusing member by the point contact between the pointed fulcrum member provided on the focusing member and the fulcrum member having the conical recess provided on the tracking member. However, the present invention is not limited to this, and a pointed member may be provided on the tracking member side, and a member having a conical concave portion may be provided on the focusing member.

Further, the specific shapes and structures of the respective parts shown in the above-described embodiments are merely examples of the embodiment for carrying out the present invention, and the technical scope of the present invention is thereby reduced. It should not be interpreted restrictively.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the optical pickup device of the present invention together with FIG. 2 to FIG. 4, and FIG. 1 is an overall side view.

FIG. 2 is an enlarged plan view of a two-axis actuator.

FIG. 3 is a sectional view taken along the line III-III in FIG. 2;

FIG. 4 is an exploded perspective view of a biaxial actuator.

FIG. 5 is an enlarged sectional view of a conventional optical pickup device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Optical pickup apparatus, 2 ... Base, 3 ... Biaxial actuator, 4 ... Objective lens, 6 ... Optical disk, 7 ... Signal recording surface, 9 ... Focusing member, 10 ... Tracking member, 14 ... Elastic member, 18 ... A fulcrum member, 23 ... a fulcrum member, 24 ... a concave portion, 36 ... a first elastic portion, 37 ... a second
Elastic part

Claims (4)

[Claims] 1. A base which is moved in a radial direction with respect to a signal recording surface of an optical disk, a two-axis actuator supported by the base, and a signal recording surface of the optical disk which is moved by the two-axis actuator. An optical pickup device comprising an objective lens moved in a focusing direction and a tracking direction, wherein the biaxial actuator comprises: a focusing member movably supported in a direction perpendicular to a signal recording surface of the optical disc; An optical pickup device, comprising: a tracking member that supports a lens and is rotatably supported by the focusing member, wherein the tracking member is supported by the point-contact with the focusing member. 2. A fulcrum member fixed to a focusing member, the tip of which is formed in a pointed shape, a conical recess is formed in an end surface of a fulcrum member provided on a tracking member, and the cusp of the fulcrum member is covered. 2. The optical pickup device according to claim 1, wherein the optical pickup device is inserted into a concave portion of the fulcrum member to make point contact. 3. The focusing member is supported by a base side member via a first elastic portion, and the tracking member is supported by the focusing member via a second elastic portion. An optical pickup device according to item 1. 4. The focusing member is supported on a base member via a first elastic portion, and the tracking member is supported on the focusing member via a second elastic portion. An optical pickup device according to item 1.