JPS635808B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for moving an objective lens vertically and horizontally in an optical pickup device, and particularly relates to a device for moving an objective lens vertically and horizontally in an optical pickup device, and in particular, a tracking drive unit and a focus drive unit are moved via a tracking movement frame, a parallel plate spring for focus, and a vertical and horizontal movement unit. The present invention relates to a device for vertically and horizontally moving an objective lens of an optical pickup device, which is arranged parallel to and on the same line as a disk, and uses a pair of square bar-shaped permanent magnets as focus drive permanent magnets.

An example of focus and tracking control in a conventional optical pickup device is shown in Figs. 1 and 2. According to these, focus (Z-axis direction control is performed by a voice coil electromagnetic drive, and tracking (X-axis direction) control is performed by a linear motor. This is done by electromagnetic driving, and the object to be driven is the objective lens 1 in both cases.

That is, a cylindrical permanent magnet 4 to which the objective lens 1 is fixed is mounted on a parallel plate spring 3 for tracking mounted inside the lens barrel 2, and a voice coil 5 is provided around the middle of the lens barrel 2, protruding from the middle part of the lens barrel 2. A cylindrical permanent magnet 4 and a voice coil 5 are arranged in a linear motor electromagnetic drive unit 7 installed in the upper part of the storage cylinder 6 and in a voice coil electromagnetic drive unit 8 installed in the middle part of the storage cylinder 6, respectively. The lens barrel 2 is held inside the storage barrel 6 using a focus parallel plate spring 9 having a circular hole in the center, and the direction of the current flowing in the voice coil 5 and the coil 10 in the linear motor electromagnetic drive unit 8 is determined. Objective lens 1 depending on the size
is moved in the Z-axis direction or the X-axis direction. In this way, the tracking drive section and the focus drive section are arranged in two stages perpendicular to the disk D.

In this prior art, it is desirable that the tracking parallel plate spring 3 has a small spring constant in order to widen the range of tracking operation, and it is also necessary to have a somewhat large spring constant in order to be able to stand on its own. Furthermore, metal is preferable because it is not affected by temperature changes. Taking all of the above into consideration, long metal leaf springs are generally used. Accordingly, the size _H1 of the optical pickup device in the Z-axis direction becomes large, which poses a problem in that the optical pickup device becomes large and heavy.

In addition, when the housing of the disk rotation drive motor and the optical pickup housing body are on the same side, when picking up the inner circumference of the disk, the separation distance R ₁ between the optical axis and the outer surface of the optical pickup housing in the disk radial direction must be as small as possible. However, since the focus drive unit composed of the voice coil 5 and the voice coil electromagnetic drive unit 8 and the objective lens 1 are arranged concentrically, there is a problem that the size cannot be reduced beyond a certain level.

This invention has been made by focusing on the problems of the prior art, and is designed to move the tracking drive section and the focus drive section relative to the disk via a tracking movement frame, a parallel plate spring for focus, and an up/down/left/right movement section. It is an object of the present invention to solve the above-mentioned problems by arranging the permanent magnets in parallel and on the same line and using a pair of rectangular bar-shaped permanent magnets as focus drive permanent magnets.

The present invention will be explained below based on the drawings.

FIG. 3 is an exploded perspective view showing an embodiment of the present invention.

First, the structure will be explained. Reference numeral 11 denotes a focus drive permanent magnet, which has the shape of a pair of square rods. The focus drive permanent magnet 11 includes a permanent magnet piece 11A with a rectangular cross section, a magnetic piece 11B with a rectangular cross section fixed to the upper surface of the permanent magnet piece 11A, and a permanent magnet piece 11
Magnetic piece 11C with an L-shaped cross section fixed to the lower surface of A
A gap 11D is formed between the magnetic pieces 11B and 11C. The focus driving permanent magnet 11 is attached to the optical pickup housing 12.
1, the longitudinal direction of which is parallel to the tracking movement direction (X-axis direction).
It is fixed to a pair of focus drive permanent magnet supports 12B, and its longitudinal direction is parallel to the tracking movement direction (X-axis direction).

By using a pair of rectangular bar-shaped permanent magnets 11 for focus driving, the separation distance R ₂ between the optical axis and the outer surface of the optical pickup housing 12 shown in FIG. 4 can be made smaller than when using a cylindrical magnet.

13 is a vertically and horizontally moving section, which is a cube. A focus control rectangular coil 14 disposed in the gap 11D of the focus drive permanent magnet 11 is protruded around the middle of the vertical and horizontal moving section 13, and the objective lens 1 is attached to the center.

Reference numeral 15 denotes a tracking movement frame whose longitudinal direction is approximately parallel to the tracking movement direction (X-axis direction) and whose dimensions are similar to the square coil 14 for focus control.
Four horizontal pieces 15A, 15B, 15 larger than the dimension parallel to the tracking movement direction (X-axis direction) of
C, 15D, and one vertical piece 15E whose longitudinal direction is substantially perpendicular to the tracking movement direction (X-axis direction).

The tracking moving frame 15 has an inner horizontal piece 15.
The distance D between B and 15C is set larger than the distance D' of the focus drive permanent magnet 11 in the direction perpendicular to the tracking movement direction (X-axis direction), and the right end of the four horizontal pieces 15A, 15B, 15C, and 15D is set at 1. It is fixed to each vertical piece 15E.

Although the vertical piece 15E is shown as having a planar shape, it may have a straight shape. Horizontal piece 15A,
The space 15F formed in the vertical piece 15D and the vertical piece 15E is for inserting a parallel plate spring for tracking, which will be described later, when the tracking moving frame 15 is attached to the optical pickup housing 12.

The tracking moving frame 15 has horizontal pieces 15B, 15
A focus drive permanent magnet support 12 is placed in a substantially U-shaped space formed by C and the vertical piece 15E.
B, the focus drive permanent magnet 11 and the vertically and horizontally moving section 13 are arranged. 16 is a parallel plate spring for tracking, which is located at the left end of the horizontal pieces 15B and 15C of the tracking moving frame 15;
Both side walls 12C, 12 have one end fixed to the right side surface of the vertical piece 15E and are parallel to the tracking movement direction (X-axis direction) of the optical pickup housing 12.
The other end is fixed inside D. The tracking parallel plate spring 16 elastically supports the tracking movement frame 15 freely in the tracking movement direction (X-axis direction). Note that the other end of the tracking parallel plate spring 16 may be fixed to a mounting piece 12E protruding from the inside of both side walls 12C, 12D of the optical pickup housing 12.

Reference numeral 17 denotes a focus parallel plate spring, the lower surface of which is in contact with the bottom surface 12A of the optical pickup housing, and the upper surface of which is in contact with the lower surface of the vertically and horizontally moving section 13 and the outer horizontal pieces 15A and 1 of the tracking moving frame 15.
The lower part 17A is in contact with the lower surface of 5D, and the lower surface is the upper surface of the focus control rectangular coil 14 and the outer horizontal pieces 15A and 15D of the tracking movement frame 15.
It is comprised of an upper part 17B which is in contact with the upper surface and whose upper surface is in contact with the upper surface 12F of the optical pickup housing 12. and top 1
7B and the lower part 17A, the central part is rectangular in plan, with a through hole in the center for the passage of the light beam, and one of the two ends is parallel to the tracking movement direction (X-axis direction) of the central part. It is formed by protruding from the plane an inverted eight-shaped piece, and a piece parallel to the tracking movement direction (X-axis direction) is connected to the tip, and the other of both ends is parallel to the tracking movement direction (X-axis direction). A planar eight-shaped part projects from the other parallel surface, and a piece parallel to the tracking movement direction (X-axis direction) is connected to the tip thereof.

The gap distance parallel to the tracking movement direction (X-axis direction) on the center side of both ends of the lower part 17A of the parallel plate spring 17 for focus is such that the permanent magnet support base 12B for focus driving is closer to the lower part 17A of the parallel plate 17 for focus. It is also set so that it is in a protruding state. The focus parallel plate spring 17 elastically supports the vertically and horizontally moving section 13 at both ends thereof so as to freely support the focus moving direction (Z-axis direction).

By making the plane shape of the focus parallel plate spring 17 as described above, the length in the direction perpendicular to the tracking movement direction (X-axis direction) can be shortened even if the spring length is the same. In addition, when the vertical piece 15E of the tracking movement frame 15 has a planar shape, the separation distance parallel to the tracking movement direction (X-axis direction) of the tracking parallel plate spring 16 can be increased, so that the tracking movement during tracking retention can be increased. There is an advantage that the inclination of the frame 15 is reduced.

Furthermore, as shown in FIG. 4, the left side wall 12F of the optical pickup housing 12 can be formed into an arcuate central portion, thereby increasing the housing diameter of the disk rotation motor.

Reference numeral 18 denotes a rectangular coil for tracking control, which is protruded from the right side wall of the center of the vertical piece 15E of the tracking movement frame 15.

Reference numeral 19 denotes a tracking drive permanent magnet, which includes two permanent magnet pieces 19A and 19B, a flat T-shaped magnetic piece 19C which is clamped between the S poles of the two permanent magnet pieces 19A and 19B, and two permanent magnet pieces 19A and 19B. It is composed of magnetic pieces 19D and 19E having a planar L-shape and a planar inverted L-shape fixed to the N pole side of the permanent magnet piece. A gap 19F is formed between the magnetic piece 19C and the magnetic piece 19D and between the magnetic piece 19C and the magnetic piece 19E. Permanent magnet 1 for tracking drive
9 is the right side wall 12 of the optical pickup housing 12.
A rectangular coil 18 for tracking control is inserted into the gap 19F. In this way, the tracking drive section consisting of the tracking drive permanent magnet 19 and the tracking control rectangular coil 18 includes the tracking movement frame 15, the parallel plate spring 17 for focusing, and the vertical and horizontal movement section 13.
A focus drive section consisting of a focus drive permanent magnet 11 and a focus control rectangular coil 14 is arranged parallel to and on the same line as the disk D. Therefore, the size _H2 in the Z-axis direction of the optical pickup device shown in FIG. 5 is reduced, and the optical pickup device can be made thinner. The size of the focus control rectangular coil 14 in the longitudinal direction (X-axis direction) is determined by the tracking movement (X-axis direction).
The focus control square coil 14 is set so as not to come into contact with the focus drive permanent magnet 11 in the axial direction). In addition, square coil 1 for tracking control
The height of 8 is determined so that the tracking control rectangular coil 18 does not come into contact with the magnetic piece 19C of the tracking drive permanent magnet 19 during focus movement (Z-axis direction).

Next, the action will be explained. When the focus error signal or the tracking error signal is zero, no current flows through the focus control rectangular coil 14 or the tracking control rectangular coil 18, and the objective lens 1 remains stationary at a predetermined position. If there is a focus error signal now, a current flows through the focus control rectangular coil 14. Since the direction of this current and the direction of the magnetic flux from the focus drive permanent magnet 11 are perpendicular to each other, the focus control rectangular coil 14 receives a force in the vertical direction (Z-axis direction) based on Fleming's left hand rule. Since the focus control rectangular coil 14 is integrated with the vertical and horizontal moving section 13 and is elastically supported by the focus parallel plate spring 17, it moves in the vertical direction (Z-axis direction). Accordingly, the objective lens 1, which is integrated with the focus control rectangular coil 14 and the vertical and horizontal moving section 13, also moves in the vertical direction (Z-axis direction). Note that the direction and amount of movement are determined by the direction and magnitude of the current flowing through the focus control rectangular coil 14. Next, when there is a tracking error signal, a current flows through the tracking control rectangular coil 18. Since the direction of this current and the direction of the magnetic flux from the tracking drive permanent magnet 19 are perpendicular to each other, the tracking control rectangular coil 18 receives a force in the left-right direction (X-axis direction) based on Fleming's left-hand rule. The square coil 18 for tracking control is the parallel plate spring 1 for tracking.
6. It is integrated with the tracking moving frame 15 and is elastically supported in the left-right direction (X-axis direction) by the tracking parallel plate spring 16 attached to the tracking moving frame 15. Move to. Therefore, the square coil 18 for tracking control and the tracking moving frame 1
5. The objective lens 1, which is integrated with the focus parallel plate spring 17 and the up/down/left/right moving section 13, also moves in the left/right direction (X-axis direction). The direction and amount of movement are determined by square coil 1 for tracking control.
It is determined by the direction and magnitude of the current flowing through 8. Note that the focus error signal and the tracking error signal are generated by the semiconductor laser 2 as shown in FIG.
0 laser beam is guided to the collimator lens 21, polarizing beam splitter 22, 1/4 wavelength plate 23, 90° deflection mirror 24, and objective lens 1, and the reflected light from disk D is guided to the polarizing beam splitter 22 in the reverse order. It is obtained by returning the light to 90° and guiding it to a 4-split sensor via a light shielding plate and a converging lens (not shown).

As explained above, the present invention arranges the tracking drive section and the focus drive section parallel to and on the same line with respect to the disk via the tracking movement frame, the parallel plate spring for focus, and the vertical and horizontal movement section. By using a pair of rectangular rod-shaped permanent magnets for focus driving, the optical pickup device can be made thinner, and the distance between the optical axis and the outer surface of the optical pickup housing can be reduced. This effect can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of the prior art, FIG. 2 is an exploded perspective view of a tracking drive unit of the prior art, FIG. 3 is an exploded perspective view showing an embodiment of the present invention, and FIG. 4 is an embodiment of the present invention. FIG. 5, which is a plan view showing an example, is a schematic cross-sectional view taken along the line AA' in FIG. 4, including the optical system. 1... Objective lens, 2... Lens barrel, 3... Parallel leaf spring for tracking, 4... Cylindrical permanent magnet, 5... Voice coil, 6... Storage tube, 7...
Linear motor electromagnetic drive section, 8...Voice coil electromagnetic drive section, 9...Parallel plate spring for focus, 10
... Coil, 11 ... Permanent magnet for focus drive, 12 ... Optical pickup housing, 13 ...
... Up/down/left/right moving unit, 14... Square coil for focus control, 15... Tracking moving frame, 16...
... Parallel plate spring for tracking, 17... Parallel plate spring for focus, 18... Rectangular coil for tracking control, 19... Permanent magnet for tracking drive, 20... Semiconductor laser, 21... Collimator lens, 22... Polarized light Beam splitter, 23...
...1/4 wavelength plate, 24...90° deflection mirror.

Claims (1)

[Claims] 1 A pair of corners made of a permanent magnet piece and a magnetic piece fixed to a pair of focus drive permanent magnet supports whose longitudinal direction is parallel to the tracking movement direction and protrudes from the bottom surface of the optical pickup housing. A vertical and horizontal moving part including a rod-shaped permanent magnet for focus driving, a rectangular focus control coil disposed in the gap between the permanent magnets for focus driving, protruding around the middle part, and an objective lens mounted in the center part; , the distance between two inner horizontal pieces of the four horizontal pieces whose longitudinal direction is substantially parallel to the tracking movement direction and whose dimension is larger than the dimension parallel to the tracking movement direction of the square focus control rectangular coil. The right end of the four horizontal pieces is fixed to one vertical piece whose longitudinal direction is substantially perpendicular to the tracking movement direction, and the distance is larger than the spacing of the focus driving permanent magnets in the direction perpendicular to the tracking movement direction. a tracking moving frame arranged such that the focus driving permanent magnet and the vertical and horizontal moving section are arranged in a space formed by the two inner horizontal pieces and the vertical piece; and the tracking moving frame. 2
One end is fixed to the side surface of the inner horizontal piece and the vertical piece, and the other end is fixed to the inner side of both side walls parallel to the tracking movement direction of the optical pickup housing, thereby elastically supporting the tracking movement frame. a pair of parallel plate springs for tracking, the lower surface of which is in contact with the bottom surface of the optical pickup housing, and the upper surface of which is in contact with the lower surface of the vertically and horizontally moving section and the lower surface of the outer horizontal piece of the tracking moving frame; The lower surface is in contact with the upper surface of the rectangular focus control coil and the upper surface of the outer horizontal piece of the tracking moving frame, and the upper surface is in contact with the upper surface of the optical pickup housing for vertical and horizontal movement. a parallel plate spring for focusing elastically supporting the optical pickup housing; a rectangular coil for tracking control protruding from the right side wall of the central part of the vertical piece of the tracking movement frame; The objective lens of an optical pickup device consists of a permanent magnet for tracking drive consisting of a permanent magnet piece and a magnetic piece, which are fixed to the right inner wall and partially inserted into the hollow part of the rectangular coil for tracking control. Mobile device.