JPH09102133A - Optical pickup - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical pickup capable of obtaining good servo characteristic by increasing the rigidity of a fixed part increasing resonant frequency for deforming a fixed part and to provide an optical pickup obtaining good servo characteristic. SOLUTION: The rigidity for connecting plural places of the vicinity of a holding member 19 fixed to a carriage 21 and further the vicinity of a holder 15 separated from here are increased. The resonant frequency for deforming the fixed part of the holding member 19 and the carriage 21 is increased, the driving force from the carriage 21 to an objective lens 6 is property transferred at the time of movement of the movable part 7 and good servo characteristic is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information recording and / or reproducing apparatus using a CD-ROM, a magneto-optical disk, a phase change disk or the like as an information recording and / or reproducing medium.
The present invention relates to an optical pickup in an optical recording / reproducing device.

[0002]

2. Description of the Related Art An optical pickup in an optical recording / reproducing apparatus is a support drive mechanism for access that moves an optical spot on an optical disk to all tracks in the radial direction (tracking direction) of the optical disk, and a fine optical spot in the radial direction of the optical disk. Support drive mechanism for tracking to move to
It has three types of support drive mechanisms, namely a support drive mechanism for focusing, which moves the light spot in a focus direction perpendicular to the recording surface of the optical disc.

In this case, in order to reduce the size and cost of the optical pickup, there has been proposed a structure in which the supporting drive mechanism for access and the supporting drive mechanism for tracking are combined. The optical pickup (conventional example 1) shown in FIGS. 11 and 12 is proposed in Japanese Patent Laid-Open No. 63-224037, which uses an objective lens 50 for forming a light spot on an optical disk. The movable part 51 has x by two guide rails 52 fixed to the base.
It is slidably supported in the direction (tracking direction).

By providing a coil 53 and a magnetic circuit 54 for both access and tracking operations, x
The drive is performed in the direction, and the access drive and the tracking drive are performed. Further, a fixing member 57 to which one end of a focus spring 56 is fixed is provided on the carriage 55, and an objective lens 50 and a holder 59 to which a focus coil 58 is attached are arranged on the other end side of the focus spring 56. Has been done.

The objective lens 50 is movably supported in the z direction (focus direction) by parallel focus springs 56, and is driven in the z direction by a focus coil 58 and a magnetic circuit 54. Next, the optical pickup shown in FIGS. 13 and 14 will be described.
This optical pickup (conventional example 2) is disclosed in JP-A-4-2430.
The movable portion is disclosed in Japanese Patent Publication No. 21 and is movable in a direction (x direction) orthogonal to the recording track of the optical disc, like the optical pickup described above.

The optical pickup 60 includes a roller 65 attached to a carriage 64 and a guide rail (not shown).
And is driven by the linear actuator 67. The optical pickup 60 includes an objective lens assembly 68.
Is fixed to the carriage 64 with a screw.

The objective lens assembly 68 is provided in a housing 69.
This is a unit configuration in which the objective lens 70 and the raising mirror 71 are incorporated. The objective lens assembly 68 has mounting portions 74a to 7ad around the bottom surface 73 of the bottom plate 72. The carriage 64 has a storage portion 75 having an opening at the top for storing the objective lens assembly 68 in the center. Storage 75
In the vicinity of the four corners of the upper surface of the bottom plate 76 of the
a to 77d are formed.

The objective lens assembly 68 is accommodated in the storage portion 75, and the mounting portions 78a to 78d are attached to the mounting base portions 74a to 7d.
The carriage 64 is fixed by being screwed from the bottom plate side of the carriage 64 by four screws 78a to 78d in a state where the carriage 64 is placed in contact with the carriage 4d.

[0009]

By the way, the above-mentioned conventional example 1
Then, when the movable portion 51 is driven in the x direction, the coil 53
To carriage 55, fixing member 57, focus spring 5
6. The force is transmitted to the objective lens 50 and the objective lens 50 is driven in the x direction. In this case, the mass of the objective lens 50 or the like is applied to the tip of the focus spring 56, and the carriage 5
Resonance is generated in the fixing member 57 on the upper part 5 as shown by the arrow in FIG. When this resonance occurs, the transfer characteristic from the coil 53 to the objective lens 50 deteriorates,
The tracking or access servo characteristics deteriorate.

The influence of this resonance occurs even when the support and drive mechanisms for access and tracking are provided separately, but it is even greater in the case of the prior art example 1. The data shown in FIG. 15 shows the data about the flexural resonance when the holding member having one end of the focus spring 56 fixed to the carriage 55 is fixed at only one position (only near the fixing portion of the spring). It is a thing. As shown in the figure, are shown the frequency of the resonant frequency by the circle portion, the frequency is low (frequency 6.6kH _z).

Similarly, in the case of the conventional example 2, it is necessary to increase the rigidity of the optical pickup and increase the resonance frequency. However, the carriage 64 has an upper part for accommodating the objective lens assembly 68 as an opening. There is a part 75, and this storage part 7
Therefore, the rigidity of the carriage 64 is reduced because of 5. Also, as shown in FIG. 13, the optical pickup of Conventional Example 2
The optical pickup 60 is deformed by twisting about the y-axis, or the side walls 81 and 82 of the carriage 64 shown in FIG.
The resonance frequency having a resonance mode in which is deformed as indicated by arrows C and D is significantly reduced. If there is such a resonance mode having a low frequency, tracking servo or focusing servo becomes unstable, and good servo characteristics cannot be obtained.

The present invention has been proposed to solve the above-mentioned problems, and increases the rigidity of the periphery of the fixing portion for fixing the spring holding member to the carriage or the rigidity of the carriage to increase the resonance frequency at which the optical pickup deforms. However, it is an object of the present invention to provide an optical pickup having good servo characteristics.

[0013]

In order to achieve the above object, the present invention provides: An objective lens; a holder for holding the objective lens; an elastic support member having one end fixed to the holder; and a holding member having the other end of the elastic support member fixed. The optical pickup has the first portion fixed to the carriage and the second portion separated from the first portion fixed to the carriage.

2. Objective lens, holder for holding the objective lens, elastic support member having one end fixed to the holder, holding member having the other end of the elastic support member fixed, and optical path of light flux reaching the objective lens And a carriage having a concave portion or an opening portion formed therein for forming an optical pickup in which the concave portion or the opening portion of the carriage is connected by a connecting member.

3. In the optical pickup according to the first aspect, a contact portion is formed at a fixing portion between the first portion of the holding member and the carriage so that the first portion can be tilt-adjusted with respect to the carriage, and the second portion. A slight gap is formed between the fixing portion and the carriage, and an adhesive is injected into this gap to form an optical pickup. Since the rigidity of the vicinity of the fixed portion of the focus spring holding member fixed to the carriage is improved by the first item, the resonance frequency at which the fixed portion deforms increases, and the driving force from the carriage to the objective lens is increased when the movable portion moves. Is properly transmitted.

According to the second aspect, since the edge of the recess or the opening is connected by the connecting member to the carriage having the low rigidity due to the recess or the opening formed in the carriage, the rigidity of the carriage is improved, The resonance frequency rises and good servo characteristics are obtained. According to the third aspect, when the tilt of the holding member with respect to the carriage is adjusted, the tilt can be smoothly adjusted through the portion configured to be able to follow the tilt adjustment. Further, the holding member and the carriage are connected via an adhesive.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. 1 to 7 show a first embodiment of the present invention, in which FIG. 1 is a perspective view of an optical recording / reproducing apparatus, and FIG. 2 is a longitudinal sectional view in the vicinity of the movable portion, and FIG. Is a vertical cross-sectional view seen from the other direction, FIG. 4 is an exploded perspective view of the movable part, FIG. 5 is a perspective view of the movable part with the cover removed, and FIG. 6 is a relationship between the movable part and the yoke. FIG. 7 is an exploded perspective view showing the frequency response in the tracking direction.

As shown in the figure, a spindle motor 3 for rotating an optical disk 2 is fixed on a deck base 1 (FIG. 1). The optical disc 2 is held in the cartridge 4 (FIG. 2). Further, a movable portion 7 having an objective lens 6 for forming a light spot 5 on the information recording surface 2a of the optical disc 2 is arranged so as to be drivable in the x direction (tracking direction) with respect to the deck base 1 (FIG. 2). ).

Further, as shown in FIG. 1, the deck base 1
The fixed optical system 8 is provided on the x (−) side of the. The fixed optical system 8 includes a laser light source 9, a beam splitter 10,
Collimating lens 11, error detection hologram 12,
It has a photo detector 13 and the like. Then, the light emitted from the laser light source 9 is transmitted through the beam splitter 10, converted into parallel light by the collimator lens 11, passes through the opening formed in the movable portion 7, is reflected by the mirror 14, and is collected by the objective lens 6. It is irradiated with light and connects a light spot 5 to the information recording surface 2a of the optical disc 2 (FIG. 2).

The light reflected here takes the reverse path to the beam splitter 10. The light reflected by the beam splitter 10 is diffracted by the error detection hologram 12 and enters the photodetector 13. Then, a reproduction signal, a tracking error signal, and a focus error signal are obtained from the output signal from the photo detector 13 (FIG. 1).

Next, the movable portion 7 will be described. The objective lens 6 is fixed to the central portion of a holder 15 made of plastic such as liquid crystal polymer. A focus coil 16 formed by winding an aluminum wire or a copper clad aluminum wire in a square shape is fixed to both side surfaces of the holder 15 in the y direction (FIG. 2). Further, as shown in FIG. 3, which is a vertical cross-sectional view of the movable portion 7 viewed from the other direction, x of the holder 15 is
Focus springs 17, 1 are provided on both sides of the (-) direction side in the z direction.
8 is fixed to one end, and the other end is fixed to the fixing surface 19 of the holding member 19.
It is fixed to a and 19b.

As shown in FIG. 4, which is an exploded perspective view of the drive unit 7, the focus springs 17, 18 are substantially rectangular and have spring constant adjusting and focus springs 17, 1 at both ends.
Positioning holes 17a, 17b, 1 to the assembly jig 8
8a and 18b are formed. The focus springs 17 and 18 are located parallel to each other and extend in the x direction. The focus springs 17 and 18 have a thickness t of 20 μm.
It is formed by etching a thin non-magnetic stainless steel plate of about m.

As described above, the focus driving section 7a is adapted to perform focus driving by the objective lens 6, the holder 15 and the focus coil 16. Further, as shown in FIG. 3, the damper forming portions 19c and 19d are connected to the fixing surfaces 19a and 19b of the holding member 19 so that the focus spring 1
It is formed as a gap of about 0.2 to 1 mm between 7, and 18. Therefore, a thermosetting and uncured damper 20 such as silicon gel is injected into the damper forming portion 19c and held by surface tension, and then heated and cured. Then, the focus spring 17 fixed to the holding member 19 is damped. The same applies to the focus spring 18.

Contact points 19e and 19f (19f is two points) whose tip is centered at the nodal point of the objective lens 6 and is part of a spherical surface are formed on the x (-) side of the holding member 19. Has been done. The three contact points are the mounting surface 21 that is a part of the cylindrical surface formed on the carriage 21.
It is in contact with a. The center of this mounting surface 21a coincides with the nodal point of the objective lens 6.

Further, the non-magnetic stainless spring 36 is shown in FIG.
As shown in FIG. 3, the y-direction both sides 36a of the rear surface of the spring 36 are disposed substantially in the center of the drive portion 7, and the tip portion 36 is formed on the x (−) side surface of the convex portion 21b formed substantially in the center of the carriage 21.
xb of the groove 19h formed on both sides in the y direction of the convex portion 19g projecting b from the substantial center of the holding member 19 in the x (+) direction.
It is brought into contact with the surface on the (+) side (FIGS. 3 and 4).

By pushing the holding member 19 and the carriage 21, the contact point 19 of the holding member 19 is pushed.
The three points e and 19f are pressed against the mounting surface 21a. Therefore, by rotating the holding member 19 around the x-axis or moving in the z-direction with respect to the carriage 21, it is possible to adjust the inclination of the objective lens 6 around the x-axis or the y-axis with respect to the carriage 21.

After adjusting the inclination in this way, an adhesive is injected between the mounting surface 21a and the surface of the holding member 19 on the x (-) side to cure the adhesive. Further, y of the convex portion 21c formed on the carriage 21 and the convex portion 19g of the holding member 19
An adhesive is also injected into the gap of about 0.2 mm between both sides in the direction to cure the adhesive. Therefore, the holding member 19 is adhered and fixed to the carriage 21 at a rear surface of the x (−) side and two positions of the tip portion on the x (+) side in total.

The carriage 21 is an integrally molded plastic product, and the material thereof is, for example, an epoxy resin containing spherical silica or a thermoplastic polyimide resin containing 30% carbon fiber. In addition, the carriage 21
An inclined surface 21d of 45 ° is formed on the z (−) side of the objective lens 6 at a substantially central portion of the mirror 14, and the mirror 14 is fixed thereto. In addition, y on the carriage 21 on both sides of the mirror 14
Coil mounting portions 21e are formed on both sides in the direction, and the two sides of the tracking coil 22 wound in the shape of a quadrangular prism are bonded and fixed thereto.

A large recess 21h is formed in the center of the carriage 21 for positioning the light flux from the mirror 14, the focus spring 18, the holding member 19 and the fixed optical system 8 to the mirror 14. Further, an opening 21f through which a guide rail 28 described later penetrates is also formed.
Further, a magnet 23 magnetized in the y direction is fixed substantially at the center of the z (−) side surface of the carriage 21 (FIG. 2,
(Fig. 4).

Further, one end 24a of an FPC 24 (flexible printed circuit board) for supplying power to the focus coil 16 and the tracking coil 22 is fixed to the lower surface of the carriage 21 on the z (-) side, and the y of the tracking coil 22 is fixed.
The reinforcing plate 24b of the FPC 24 is fixed to the (+) side. A bent portion 24c that bends and deforms when the movable portion 7 moves in the x direction from this fixed portion extends in a U-shape in one direction, and the tip of the extended portion is raised to the deck base 1 to form the convex wall 1a surface. It is designed to be guided (Figs. 1 and 4).

The bent portion 24c fixed to the movable portion 7
The center point P of the fixed end of the is aligned with the center of gravity G of the movable part 7 when viewed from the y direction and the centers of bearings 25 and 26 on the reference side which will be described later and are separated in the x direction which is the moving direction of the movable part 7. Has become. Therefore, the movable portion 7 is prevented from being tilted by the bending reaction force and the inertial force of the bending portion 24c (FIG. 2).

As shown in FIG. 5, the upper surfaces (the surfaces on the z (+) side) of the carriage 21 and the tracking coil 22 are
A cover 27 made by pressing a thin plate of non-magnetic stainless steel having a magnetic permeability of 1.1 or less such as SUS316 and SUS310 is adhered and fixed. Attachment part 27a of this cover 27
Closes the opening 21f of the carriage 21 to reinforce the carriage 21. Further, since the mounting portion 27a is adhesively fixed to each of the tracking coil 22 so as to connect the z (+) side surface of the tracking coil 22 and the carriage 21, the mounting portion 27a reinforces the z (+) side surface of the tracking coil 22. .

Further, since the connecting portion 27b is formed in the cover 27 so as to connect the upper portion of the opening 21h of the carriage 21, the torsional rigidity of the movable portion 7 around the y axis is improved. Further, as shown in FIG. 2, a through hole in the x direction is formed near the y (+) of the carriage 21, and the x of the through hole is
Two bearings 25 on the reference side are provided integrally with the carriage 21 at positions separated in the direction. The bearing 25 has a circular cross section of a guide rail 28 inserted into the through hole.
In the shape of a cylinder having a size of about 1 to 0.4 mm, which is obliquely cut in the circumferential direction at four positions, the four planes of the inclined surface and the guide rail 28 form a clearance of about 5 to 30 μm.

Further, a through hole in the x direction is formed near the y (-) side of the carriage 21, and a bearing 26 on the driven side at the center of the x direction is provided integrally with the carriage 21.
This bearing 26 has a circular cross section cut on both sides in the z direction with a flat surface to form a clearance of about 5 to 30 μm between the flat surface and the guide rail 29 (FIG. 2). The bearing 2
5 and 26 are formed so that the surface in contact with the guide rails 28 and 29 has a surface roughness of about 0.3 to 3S, which is 6.3S or less.

The guide rails 28 and 29 are made of non-magnetic stainless steel such as SUS304, and the surface of the guide rails 28 and 29 is coated with a fluorine-based material.
It is polished to a certain degree so that the coating thickness is 5 to 20 μm. Both sides of the guide rails 28, 29 in the length direction are fixed to the mounting corners 1b of the deck base 1 via springs 30.

With such a structure, the guide rail 28 serves as the bearing 25, and the guide rail 29 serves as the bearing 26.
The movable portion 7 is moved by being inserted into and abutted on the movable member 7 and sliding in the x direction. As shown in FIGS. 1, 2 and 6, center yokes 31 are inserted through the tracking coils 22 on both sides in the y direction so as to be juxtaposed with the guide rails 28 and 29, and a short ring is provided in the center of the center yoke 31. 32 is fixed.

Both sides in the length direction of the center yoke 31 are fixed to the mounting portion 1c of the deck base 1 with screws. A substantially U-shaped side yoke 33 is arranged so as to be located above the center yoke 31 on the z (+) side and in the opening 4a of the cartridge 4, and the side yoke 33 is provided on the z (−) side thereof.
Magnets 34a, 34b magnetized in the direction are fixed.

Both sides of the side yoke 33 are in contact with the center yoke 31, and the center yoke 31, the side yoke 33, and the magnets 34a and 34b form a magnetic circuit. Further, the magnet 23 is magnetized so that its magnetic pole in the y direction is the same pole as the magnets 34a and 34b. Therefore, the N pole of the magnet 34a and the N pole of the magnet 23, the S pole of the magnet 34b and the magnet. The S pole of 23 repels and pushes the movable part 7 in the z (-) direction.
Therefore, the two surfaces of the bearing 25 on the z (+) side are the surfaces 28a of the guide rails 28, and the two surfaces on the z (+) side of the bearing 26 are the ones.
The surface 26a is pressed against the guide rail 29 to prevent backlash.

The effective magnetic fluxes from the magnets 34a and 34b reach the center yoke 31 toward the z (+) side surface of the tracking coil 22 and the carriage 21 side surface in the y direction. Then, the tracking coil 22 mainly generates a force in the tracking direction (x direction) on the two surfaces. Therefore, the resultant force generated in the tracking direction is a point F slightly lower than the z (+) side surface of the tracking coil 22 on the z (−) side.

This point F coincides with the center of gravity G of the movable portion 7 when viewed from the x direction. The heights of F and G in the z direction are substantially the same as the upper ends of the guide rails 28 and 29, that is, the points where the preloaded bearings 25 and 26 are in contact with the guide rails 28 and 29. Therefore, the drive center F, the center of gravity G, and the center point of the frictional force generated between the bearing and the guide rail substantially coincide with each other, and rotation around the y axis when the movable portion 7 is driven in the x direction is suppressed. .

The focus coil 16 has its z
The side on the (−) side is the magnetic pole surface of the magnet 27, and z
The side on the (+) side and the side yoke 33 have substantially the same height in the z direction and are arranged close to each other. Since the magnetic flux from the magnetic pole surface of the magnet 27 to the side yoke 33 is as shown by the arrow in FIG. 2, the magnetic flux acting on the two sides of the focus coil 16 in the z direction is opposite in the y direction. Generate a force in the same direction in the z direction (Fig. 2).

With the above configuration, when a current corresponding to the focus error signal is applied to the two focus coils 16, a force in the z direction is generated on two sides in the z direction, and the objective lens 6 is moved in the z direction. It drives (FIG. 2, FIG. 3). As described above, the two focus springs 17 and 18 support the objective lens 6 so as to be movable in the z direction by bending in the z direction.

At this time, the two focus springs 17 and 18
Are damped by the damper 20. Since the damper 20 is formed by being injected into the damper forming portion 19c formed between the focus springs 17 and 18 and the holding member 19, the focus springs 17 and 18 are formed.
Since an injection part surrounding the holding member 19 is unnecessary, the holding member 19 can be downsized, and the focus springs 17 and 18 can be easily attached to the holding member 19. Since the damper 20 can be injected from the positioning holes 17a, 17b, 18a, 18b (FIG. 4) formed in the focus springs 17, 18, it can be easily performed.

Further, the light flux from the fixed optical system 8 has a hole 21g formed in the carriage 21 and a hole 19 of the holding member 19.
i, between the two focus springs 17 and 18, the holder 1
5 through the hole 9a to reach the mirror 14 (FIG. 3). As described above, since the distance between the focus springs 17 and 18 is large in order to pass the light flux between the two focus springs 17 and 18, the focus movable portion 7a can rotate around the y axis or the x axis. The resonance frequency of pitching and rolling resonance can be increased. Here, the carriage 21
By forming the opening 21h at the center and arranging the focus spring 18 there, the dimension of the movable portion 7 in the z direction is not increased even if the distance between the focus springs 17 and 18 is increased. Further, the holding member 19 is a focus spring 17,
The contact points 19e and 19 on the x (−) side, which are contact portions for adjusting the inclination, are close to the holding member side fixing surfaces 19a and 19b of the reference numeral 18.
The cylindrical surface 21 that is the mounting surface of the carriage 21 is near f
It is adhesively fixed to a (FIG. 3).

Further, the holder 15 side on the x (+) side with respect to the contact portion, that is, both sides in the y direction of the protruding portion 19g protruding in the extending direction of the focus springs 17 and 18 and the protruding portion 21c.
It is also fixed by adhesion (Fig. 5). In addition, the movable part 7
When is driven in the x direction by the tracking coil 22, the vicinity of the fixed portion of the holding member 19 which is the attachment surface 21a, that is, the fixed surfaces 19a of the focus springs 17 and 18,
In 19b, the focus movable portion 7a arranged at a position distant from this has an additional mass. Therefore, the mounting surface 21a of the carriage 21 and the fixed surfaces 19a, 19b
The vicinity of is easily deformed as shown by arrow A in FIG.

However, since the convex portion 19g distant from this portion is fixed to the carriage 21, the portion which is easily deformed can be reinforced. Therefore, the rigidity of the fixing portion between the cylindrical surface 21a and the holding member 19 and the deformed portion near the holding member fixing surfaces 19a and 19b is increased, and the resonance frequency can be improved (FIG. 3). Further, as described above, both side surfaces in the y direction of the convex portion 19g of the holding member 19 and the convex portion 21c of the carriage 21 are adhesively fixed. In other words, since the central portion of the carriage 21 in which the central portion is formed as a concave portion and the opening portion 21h is formed in a substantially box shape, the central portion of the carriage 21 is connected and reinforced by the holding member 19 which is a connecting member, so that the rigidity of the carriage 21 is improved. To improve the resonance frequency of the deformation of the carriage 21 such as the deformation of the carriage 21 twisted about the x-axis and the y-axis, the deformation in the z-direction, and the deformation of the side walls on both sides in the y-direction. You can

Since the opening 21h is connected and reinforced by the cover 27, the rigidity of the carriage 21 is further improved. Further, since the carriage 21 is reinforced by the holding member 19 and the cover 27 and no special reinforcing member is required, the number of parts does not increase and the cost of the product is not affected. Next, when a tracking error signal or the like is passed through the tracking coil 22, the magnet 27
The force in the x direction is generated in cooperation with the magnetic flux generated in a and 27b, and the light spot 5 from the movable portion 7, that is, the objective lens 6 is moved in the x direction. In this case, the movable portion 7 is guided in the x direction by sliding the two parallel guide rails 28 and 29 and the bearings 25 and 26.

In this embodiment, since there is only one means for moving the light spot 5 from the objective lens 6 in the x direction, the tracking coil 22 produces fine eccentricity and shake signals in the x direction of the recording track. In addition to the corresponding tracking signal, a current corresponding to an access signal for moving the carriage 21 over the entire recording track range of the optical disc 2 is passed. Therefore, since the tracking mechanism is single, the device configuration can be simplified and downsized.

In order to unify the tracking mechanism, it is necessary to improve the driving sensitivity of the tracking operation and increase the resonance frequency so that the movement can be performed smoothly. Therefore, in the present embodiment, in order to improve the driving sensitivity of the tracking operation, a heavy magnetic circuit is arranged not on the movable portion 7 but on the deck base 1 (FIG. 1). Further, the carriage 21, the holding member 19 and the holder 15 shown in FIG. 5 are made of plastic to reduce the weight, and the tracking coil 22 and the focus coil 16 are made of aluminum wire or copper clad aluminum wire which is lighter than copper. .

As a result of reducing the weight of the movable portion 7 in this manner, it was possible to reduce the weight to about 1.8 g. In addition, in order to improve the driving sensitivity of the tracking operation, the magnet 3
4a and 34b, [BH] max of Nd-Fe-B = 33
The magnetic flux density acting on the tracking coil 22 can be increased because a magnetic gap is formed directly between the magnets 34a and 34b and the center yoke 31 by using a grade of about 45 MGOe.

Thus, the sensitivity in the tracking direction is set to 18
It could be improved to 0 m / s ² / A, which is comparable to that of a normal tracking actuator. In this way, the movable part 7
It was possible to improve the servo characteristics by increasing the influence of resonance due to deformation of the carriage 21 when driven in the tracking direction and resonance due to deformation of the focus springs 17 and 18. As a result, conventionally those was the resonant characteristic shown in FIG. 15, as in the embodiment shown in FIG. 7, to improve the resonance frequency of the tracking direction 12KH _Z and normal tracking actuator parallel did it.
If you want to decrease the influence of the resonance In addition, taking a notch filter to the resonance frequency, it is possible to set the cutoff frequency to 1kH _Z ~4kH _Z by lowering the gain of the resonance peak, better servo The characteristics can be obtained.

As described above, in the present embodiment, the carriage 21 is reinforced by the cover 27 and the holding member 19 to improve the rigidity near the fixed portions of the focus springs 17 and 18.
The space between the two focus springs 17 and 18 is widened so that the light flux passes therethrough, and the tracking coil 22 and the focus coil 1
Since the weight of 6 is made of aluminum wire or the like, the resonance frequency can be improved.

In order to smoothly move the movable portion 7, the bearing 25 is composed of four faces as shown in FIG.
Since the contact area with the guide rail 28 is minimized by making line contact with the guide rail 28, the frictional force between the bearing 25 and the guide rail 28 can be reduced. In addition, even if dust or the like adheres to the bearing 25 and the guide rail 28,
Since it escapes into the gap formed by the bearing 25 and the guide rail 28, it is possible to avoid an increase in frictional force. This also applies to the bearing 26 and the guide rail 29.

Further, the material of the carriage 21 is a spherical silica-containing epoxy resin having a high bending elasticity and good sliding characteristics, or a thermoplastic polyimide resin containing 30% of carbon fibers, and the surface roughness of the bearings 25 and 26 is 6 The carriage 21 was molded by processing the mold so as to be about 0.3 to 3S, which is 3S or less. On the other hand, the guide rails 28 and 29 are
Fluorine coating is applied to the surface of a stainless steel round bar, the surface is polished, and the coating thickness is 5 to 20μ.
m, and the surface roughness was processed to about 0.4S, which is 3.2S or less.

Since the bearings 25 and 26 and the guide rails 28 and 29 are configured as described above, the static friction coefficient of the movable portion 7 can be set to about 0.2 which is 0.25 or less, and the dynamic friction coefficient is 0.09. Could be about. Therefore, the movable portion 7 can be smoothly driven in the tracking direction, and good servo characteristics with less tracking or access servo residual can be obtained.

Since the center yoke 31 is provided with the short ring 32, the inductance of the tracking coil 22 is about 100 μH or less and about 50 μH (f = 1k).
H _Z ) was obtained, and the response of the current passed through the tracking coil 22 could be accelerated. By the way, the first embodiment is not limited to the above configuration, and may have the following configuration. For example, although there is a single support drive mechanism for tracking and access, there are two support drive mechanisms, and a galvano mirror is provided in the fixed optical system, or the objective lens is focused on the carriage and movable in two directions of tracking. Good. Further, the supporting method of the objective lens 6 is not limited to the spring supporting method, and other supporting methods such as a so-called shaft sliding method may be used.

Next, a second embodiment of the present invention will be described. FIG. 8 (separated perspective view) and FIG. 9 (plan view) show a second embodiment of the present invention, and portions corresponding to those of the first embodiment are designated by the same reference numerals (see the following embodiment). The same applies to the form). The holding member (connecting member) 41 is formed to project in both directions of the y direction, and the x of the projected portion 41a is formed.
A concave surface (first connecting portion) 41b having the nodal point of the objective lens 6 as a center is formed on the (+) side. On the other hand, a convex surface 40a having the nodal point of the objective lens 6 at the center is also formed on the tip x (−) side of the U-shaped carriage 40 in plan view.

Therefore, the inclination of the objective lens 6 with respect to the carriage 40 can be adjusted by bringing the concave surface 41b and the convex surface 40a into contact with each other with a jig and sliding both surfaces. Thus, after adjusting the inclination, the concave surface 41
An adhesive is injected and fixed between b and the convex surface 40a.

On the other hand, the holding member 41 has x from the center thereof.
In the (+) direction, that is, in the extending direction of the focus springs 17 and 18, and between the focus springs 17 and 18, the protrusion 4 is formed.
1c is formed. The protrusions (second connecting portions) 41d on both sides in the y direction at the tip of the protrusion 41c and the wall surface 40b inside the carriage 40 are arranged with a slight gap therebetween. Then, the adhesive 42 is injected and fixed. Therefore, when adjusting the inclination of the holding member 41 with respect to the carriage 40, the position of the protrusion 41d and the wall surface 40b does not hinder the adjustment. Other configurations are similar to those of the first embodiment.

As described above, also in the second embodiment, the holding member (connecting member) 41 for fixing one end of the focus springs 17 and 18 is fixed to the fixing portion 4 of the focus springs 17 and 18.
It is adhesively fixed to the carriage 40 via two concave surfaces (first connecting portions) 41b in the vicinity of 1e, and further from the fixing portions 41e of the focus springs 17 and 18 of the holding member 41 to 2 in the vicinity of the other ends of the focus springs 17 and 18. Since the portion is adhesively fixed to the carriage 40 via the protrusion (second connecting portion) 41d, the rigidity of the holding member 41 in the twisting direction around the y-axis is dramatically improved.

Further, the focus spring 1 of the carriage 40
The openings in which the seven and eighteen are arranged are the protrusions (second connecting portions) 41 d of the holding member 41 and the wall surface 40 inside the carriage 40.
Since b and B are bonded and fixed, the bending of the carriage 40 in the z direction and the torsional rigidity around the y axis are improved. Further, since the convex surface 40a at the tip of the carriage 40 is connected to the holding member 41 by being adhesively fixed, the rigidity of the carriage 40 at this portion is also improved. In this way, the carriage 40 when the movable portion is driven in the tracking direction
It was possible to improve the servo characteristics by increasing the frequency of resonance caused by the deformation of No. 2 and the resonance caused by the deformation of the focus springs 17 and 18.

The projecting portion 41c has a holding member 41.
It may be integrally formed with or fixed as a separate component. Alternatively, the protrusion 41c may be integrally formed with the carriage 40, and the tip of the protrusion 41c may be adhesively fixed to the central portion of the holding member 41 on the x (−) side. In addition, the holding member 41
The carriage 40 and the carriage 40 may be integrally formed by connecting all the joining portions of the two. In this case, when adjusting the inclination of the objective lens 6, the inclination of the objective lens 6 is adjusted and fixed to the holder.

In the present embodiment, the holding member 41 integrally formed with the concave surface (first connecting portion) 41b and the protruding portion (second connecting portion) 41d constitutes the connecting member (concave surface 41b). Is bonded to the convex surface 40a and the projection 41d is bonded and fixed to the wall surface 40b), but the connecting member may be configured as follows. For example, the connecting member may be configured only by the holding member 41 in which the projection 41d is not formed and the concave surface 41b is adhesively fixed to the carriage 40. Alternatively, the holding member 41 having the concave surface 41b may be used as the first connecting member, and the holding member 41 may be a separate member and a second connecting member having the protrusion 41d.

The holding member 41 to which one end of the focus springs 17 and 18 is fixed is not configured as a connecting member, but the holding member 41 is fixed to another member (for example, actuator base) and The member may be used as a connecting member to be bonded and fixed to the convex surface 40a or the wall surface 40b of the carriage 40, and the concave portion of the carriage 40 may be connected.

FIG. 10 shows a third embodiment of the present invention. The carriage 43 and the holding member 44 are integrally formed, and the width of the focus spring 18 in the y direction is 1/2 that of the focus spring 17, and the focus spring 18 is arranged on both sides of the focus spring 17 in the y direction ( The focus spring 18 on one side is hidden in the drawing). Therefore, even if the carriage 43 and the holding member 44 are integrally formed, the focus spring 17 and the focus spring 18 can be easily assembled.

Further, a portion 44c protruding in the x (+) direction from the fixed portion 44a of the focus spring 17 with respect to the holding member 44, and a fixed portion 44b of the focus spring 18 are provided.
Is also integrally formed with the carriage 43. in this way,
The holding member 44 has not only the fixing portions of the focus springs 17 and 18, but also the shape extending in the x direction (the extending direction of the focus springs). Further, the carriage 43 and the holding member 4
Since 4 is integrally formed, the rigidity of the joint portion between the carriage 43 and the holding member 44 can be improved.
Therefore, the resonance caused by the deformation of the carriage 43 when the movable portion is driven in the tracking direction, the focus spring 1
It was possible to improve the servo characteristics by increasing the resonance frequency due to the deformation of Nos. 7 and 18.

The other structure is similar to that of the first embodiment. [Additional Notes] 1. An objective lens; a holder for holding the objective lens; an elastic support member having one end fixed to the holder; and a holding member having the other end of the elastic support member fixed. An optical pickup characterized in that a first portion is fixed to a carriage, and in addition, a second portion separated from the first portion is fixed to the carriage.

2. Objective lens, holder for holding this objective lens, elastic support member fixed at one end to the holder, holding member fixed at the other end of the elastic support member, and optical path of light flux reaching the objective lens And a carriage in which a concave portion or an opening portion is formed, and the concave portion or the opening portion of the carriage is connected by a connecting member.

3. The optical pickup according to appendix 1, wherein a contact surface is formed at a fixing portion between the first portion of the holding member and the carriage, the abutting surface being capable of adjusting the inclination of the first portion with respect to the carriage. An optical pickup characterized in that a small gap is formed between the portion 2 and the carriage and the adhesive is injected into the gap.

4. The optical pickup according to appendix 1, wherein the first portion of the holding member is formed on one end side of the elastic support member, and the second portion is formed on the holder side which is the other end side of the elastic support member. An optical pickup that is characterized. According to Supplementary Note 4, it is possible to improve the rigidity of the fixing portion of the holding member by providing the second portion at a location where the fixing portion of the holding member is largely deformed.

5. The optical pickup according to claim 2, wherein the connecting member is formed of the holding member. According to Appendix 2, since the holding member is the connecting member, the rigidity of the carriage can be increased without increasing the number of parts.

[0072]

As described above, according to the present invention, the following effects can be obtained. According to the first aspect of the present invention, the rigidity is improved by the connection at a plurality of points such as the vicinity of the fixed portion of the holding member fixed to the carriage and the vicinity of the holder further away from the holder, and the fixed portion of the holding member and the carriage is deformed. The frequency rises, the driving force is properly transmitted from the carriage to the objective lens when the movable portion moves, and good servo characteristics are obtained.

According to the second aspect of the present invention, the holding member is fixedly connected to the edge of the recess or opening so as to reinforce the low-rigidity recess or opening formed in the carriage, so that the rigidity of the carriage is improved and the resonance frequency is increased. Good servo characteristics can be obtained when the movable part moves. According to claim 3, apart from the contact portion for adjusting the inclination of the holding member with respect to the carriage,
Since the position that is configured to be able to be driven during tilt adjustment is the fixed position between the carriage and the holding member, the tilt can be adjusted smoothly and the rigidity can be improved by connecting the holding member and the carriage at multiple points to improve the rigidity. Good servo characteristics can be obtained when moving parts.

[Brief description of the drawings]

FIG. 1 is a perspective view of an optical recording / reproducing apparatus according to a first embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view of the vicinity of the movable part.

FIG. 3 is a vertical sectional view seen from the other direction.

FIG. 4 is an exploded perspective view of the movable part.

FIG. 5 is a perspective view of the movable portion with the cover removed.

FIG. 6 is an exploded perspective view showing the relationship between the movable portion and the yoke.

FIG. 7 is data showing a state in which the flexural rigidity is improved.

FIG. 8 is a perspective view of a movable part according to a second embodiment of the present invention.

FIG. 9 is a plan view of the same.

FIG. 10 is a perspective view of a movable portion according to a third embodiment of the present invention.

FIG. 11 is a perspective view showing a first conventional example.

FIG. 12 is a side view of the same.

FIG. 13 is a perspective view showing Conventional Example 2.

FIG. 14 is a side view of the same.

FIG. 15 shows data when only the vicinity of a fixed view of the spring is fixed.

[Explanation of symbols]

 6 Objective lens 7 Moving part 7a Focus moving part 9a Hole 14 Mirror 15 Holder 17 Focus spring 18 Focus spring 19 Holding member 19a Fixed surface 19b Fixed surface 19c Damper forming part 19e Contact point 19f Contact point 19g Convex part 19i hole 20 Damper 21 Carriage 21a Mounting surface 21g Hole

Claims (3)

[Claims] 1. An objective lens, a holder for holding the objective lens, an elastic support member having one end fixed to the holder, and a holding member having the other end of the elastic support member fixed. An optical pickup characterized in that a first portion of the holding member is fixed to a carriage, and in addition, a second portion separated from the first portion is fixed to the carriage. 2. An objective lens, a holder for holding the objective lens, an elastic support member having one end fixed to the holder, a holding member having the other end of the elastic support member fixed, and the objective lens. And a carriage in which a concave portion or an opening portion for the optical path of the light flux reaching the above is formed, and the concave portion or the opening portion of the carriage is connected by a connecting member. 3. A contact surface between the first portion of the holding member and the carriage is formed so as to adjust the inclination of the first portion with respect to the carriage, and the abutment surface is formed. 2. The optical pickup according to claim 1, wherein a slight gap is formed at a fixed portion with the carriage, and an adhesive is injected into the gap.