JPS5968835A - Left/right/up/down shifter of objective lens for optical pickup device - Google Patents

Abstract

PURPOSE:To attain a miniature and lightweight device, by providing circumferentially a focus and a tracking control coil to an objective lens holder, arranging both coils to the air gap of magnetic circuit used in common to the coils and supporting freely movably the lens holder with a tracking moving body. CONSTITUTION:Since the focus control coil 13 and the tracking control coil 14 are arranged orthogonally in the horizontal line to the objective lens holder 11, the height H2 in the Z axis is less. The magnetic circuit 15 serving also as focus tracking is formed with a magnetic substance having recessed longitudinal cross section and a permanent magnet 15A having rectangular lateral cross section. Since no magnetic circuit is arranged in the direction orthogonal to the tracking moving direction (X axis direction), the separted distance R2 between the optical axis and a housing 16 is small. A tracking parallel spring 19 is provided to side walls 18D, 18E of both ends of a tracking moving body 18 and a both side wall 16C of the housing 16 in parallel with the X axis and supports elastically the moving body 18 freely movably in the X direction from the both-side wall 16C.

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 to an objective lens holder on which an objective lens is attached and a coil cantilever protruding from the objective lens holder. A focus control coil and a tracking control coil are disposed around the circumference in directions orthogonal to each other, and both coils are placed in the gap between a pair of rectangular bar-shaped focus/tracking magnetic circuits, parallel to the disk. The present invention relates to a device for vertically and horizontally moving an objective lens of an optical pickup device, in which the objective lens holder is movably supported vertically and horizontally by a tracking moving body arranged through a focusing parallel plate No. 6 and a tracking parallel plate No. 6.

An example of focus and tracking control in a conventional optical pickup device is shown in FIGS. 1 and 2.
According to this, focus (Z-axis direction) control is performed by voice coil electromagnetic drive, and tracking (X-axis direction) control is performed by near motor electromagnetic drive, 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 tracking parallel plate 6 mounted inside the lens barrel 2, and a discoil 5 is provided around the middle of the lens barrel 2 to protrude from the middle part of the lens barrel 2. , and the cylindrical permanent magnet 4 and the voice coil 5 are arranged inside the upper part of the storage tube 6, inside the near motor electromagnetic drive section Z, and inside the voice coil electromagnetic drive section 8 installed inside the middle part of the storage tube 6, respectively. Then, using a parallel plate for focusing 9 having a circular hole in the center, the storage cylinder 6 is
The lens barrel 2 is held inside, and the objective lens 1 is moved in the Z-axis direction or the X-axis direction depending on the direction and magnitude of the current flowing through the voice coil 5''!f and the coil 10 in the linear motor electromagnetic drive section 8. 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 parallel plate spring 6 for tracking has a small force constant in order to widen the tracking operation range, and it is necessary to have a somewhat large force 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. Therefore, the height I-T of the optical pickup device in the Z-axis direction becomes large, resulting in a problem that the optical pickup device becomes large and heavy.

When the housing of the disk rotation drive motor and the optical pickup housing body are still on the same side, when picking up the inner circumference of the disk, the separation distance R1 between the optical axis and the outer surface of the optical pickup housing in the disk radial direction is: Although it is preferable to make the size as small as possible, there is a problem that it cannot be made smaller than a certain point because the focus drive unit consisting of the disc coil 5 and the disc coil electromagnetic drive unit 8 and the objective lens 1 are arranged concentrically. there were.

The present invention was made by focusing on the problems of the prior art, and includes a focus control coil and a tracking coil on an objective lens holder to which an objective lens is attached, and a coil support piece protruding from the objective lens holder. A tracking moving body in which control coils are disposed around the circumference in directions orthogonal to each other, and both coils are arranged in the gap between a pair of rectangular rod-shaped focus/tracking magnetic circuits, and are arranged parallel to the disk. The object of the present invention is to solve the above-mentioned problems by supporting the objective lens holder so as to be movable vertically and horizontally via a parallel plate spring for focusing and a parallel plate jaw for tracking.

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

FIG. 3, FIG. 4, FIG. 5, and FIG. 6 are diagrams showing one embodiment of the present invention.

First, to explain the configuration, 11 is an objective lens holder.
A circular hole 118' is bored in the vertical direction, and the objective lens 1 is mounted in the circular hole 118'.

Reference numeral 12 denotes a coil support piece, which is protruded from one side surface 11A of the objective lens holder 11. Height H of coil support piece 12
2 is set lower than the height H of the objective lens holder 11.

13 is a rectangular focus control coil, - side 11A
A side surface 12A of the coil support piece 12 parallel to the parallel side surface 11B of the objective lens holder 11 and one side surface 11A.
It is provided around the periphery with a constant gap G between both orthogonal side surfaces 110 and 11D of the objective lens holder 11, which are orthogonal to the parallel side surface 11B (or - side surface 11A). The height H3 of the focus control coil 13 is the height I of the coil support piece 12.
−■ Set lower than 2.

14 is a rectangular tracking control coil whose height is T.
-T4. The width W4 is larger than the height H3 and the height W3 of the focus control coil 16, and the upper and lower surfaces 12B of the coil support piece 12 are fitted around the focus control coil 16.
12C, and is perpendicular to the focus control coil 16. By arranging the focus control coil 13 and the tracking control coil 14 around the objective lens holder 11 and the coil support piece 12 in directions orthogonal to each other,
Since the focus control coil 16 and the tracking control coil 14 are arranged on the same horizontal line, the height I]2 of the optical pickup device in the Z-axis direction becomes small, and the optical pickup device can be made thinner.

Reference numeral 15 denotes a magnetic circuit for both focus and tracking, which is shaped like a pair of square rods. The focus/tracking magnetic circuit 15 is formed of a magnetic material having a concave vertical section and a permanent magnet 15A having a rectangular cross section. A permanent magnet 15A extends in the longitudinal direction inside the opposite side 15B of the magnetic body, and a focus control coil 13 and a tracking control coil 13 are located between the permanent magnet 15A and the other opposite side 150 of the magnetic body. A cavity 15D is formed with a size that allows the coil 14 to be placed therein. A notch 15g larger than the depth D4 of the tracking control coil 14 is formed in the lower part of the other opposing side 15C so that the tracking control coil 14 can be placed in the gap 151).

The width W5 of the other opposing side 150 is naturally smaller than the size of the gap G, and the length L5 is shorter than the inner length T, 3 of the focus control coil 16, and the end of the other opposing side 15C and the focus control coil 13 The separation distance t from the inner side is set to about 0.3 degrees. Also, the other opposing side 15 has a notch 15B at the lower part.
0 top (or bottom) and tracking control coil 1
The separation distance f from the inside of 4 should be about 1 cylinder. separation distance t,
By determining f in this way, the tracking control coil 14. Even if an overcurrent flows through the focus control coil 16, the other side 15 facing the focus control coil 13
The tracking control coil 14 is in contact with the top (or bottom) of the other opposing side 150, the tracking control coil 14 is turned on at least 0,:3 on, and the focus control coil 13 is moved at least 18. First, since these coils is and i4 also serve as stoppers when returning the circus, there is no need to provide a separate stopper. The focus/tracking magnetic circuit 15 is arranged with its longitudinal direction parallel to the tracking movement direction (X-axis direction), and is fixed to the base 16A of the optical pickup housing 16.

The orthogonal portion 13A of the focus control coil 16 is perpendicular to the side surface 11B parallel to the cavity 15D.

13B and a part of the tracking control coil 14 are arranged.

Since the magnetic circuit is not arranged in a direction parallel to the parallel side surface 11B, that is, in a direction orthogonal to the tracking movement direction (X-axis direction), the separation distance R2 between the optical axis and the outer surface 16B of the optical pickup housing 16 can be made small. . In addition, a pair of focus/tracking magnetic circuits 15 is used that uses separate magnetic circuits for focusing and tracking.
This reduces component costs and assembly costs.

Reference numeral 17 denotes a parallel plate spring for focusing, which is connected to the upper and lower parts of one side 11A of the objective lens holder 11 and the tracking moving body 18.
The objective lens holder 11 is moved from the outer end 18A to the focus movement direction (Z
It is elastically supported so that it can move freely in the axial direction.

The tracking moving body 18 has an outer end 18A having a height slightly lower than the height H'l of the objective lens holder 11, and a center part of the outer end 18A.
and a horizontal piece 18B that projects to the side and has a height lower than the height Hs of the outer end portion 18A.
A through hole 180 for weight reduction is vertically bored in B. The parallel plate spring 17 for focusing and the tracking moving body 18 are parallel to the disk D.

Reference numeral 19 denotes a tracking phase parallel plate plate, which is installed on the side walls 18D and 18E at both ends of the tracking movable body 18 and both side walls 160 of the optical pickup housing 160 parallel to the tracking movement direction (X-axis direction). 18 is elastically supported from both side walls 160 so as to be movable in the tracking movement direction (X-axis direction).

Next, the effect will be explained. When the focus error signal or the tracking error signal is zero, no current flows through the focus control coil 13 or the tracking control coil 14, and the objective lens holder 11 remains stationary at a predetermined position.

If there is a focus error signal now, a current flows through the focus control coil 16. The direction and focus of this current
Since the magnetic flux directions of the tracking magnetic circuit 15 are perpendicular to each other, the focus control coil 13 receives a force in the vertical direction (Z-axis direction) based on Fleming's left-hand rule.

Then, the focus control coil 13 is connected to the focus parallel plate spring 17 which is integrated with the objective lens holder 11.
Since it is elastically supported by, it moves in the vertical direction (Z-axis direction). Therefore, focus control coil 1
The objective lens 1, which is integrated with the objective lens 3 through the objective lens holder 11, 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 coil 13.

Next, when there is a tracking error signal, a current flows through the tracking control coil 14. Since the direction of this current and the direction of the magnetic flux of the focus/tracking magnetic circuit 15 are perpendicular to each other, the tracking control coil 14 receives a force in the left-right direction (X-axis direction) based on Fleming's left-hand rule. Then, the tracking control coil 14 is integrated with the objective lens holder 11, and is controlled in the left-right direction (X-axis direction), so it is elastically supported with respect to
Move in the left/right direction (X-axis direction). Therefore, the objective lens 1 is integrated with the tracking control coil 14 via the coil support piece 12 and the objective lens holder 11.
also moves in the left and right direction (X-axis direction). Note that the direction and amount of movement are determined by the direction and magnitude of the current flowing through the tracking control coil 14.

Note that the focus error signal and the tracking error signal are generated by converting the laser beam of the semiconductor laser 20 into the polarizing beam slittor 21 and the collimator lens 22.1, as shown in FIG.
/4 wavelength plate 23.90° deflection mirror 24, objective lens 1
The reflected light from the disk D is returned to the polarizing beam splitter 21 in the reverse order, deflected by 90 degrees, and guided to a 4-split optical sensor using a light shielding plate (not shown).

As described above, the present invention provides a focus control coil and a tracking control coil in directions orthogonal to each other on an objective lens holder to which an objective lens is attached and a coil support piece protruding from the objective lens holder. Both coils are placed in the gap between a pair of rectangular rod-shaped focus tracking magnetic circuits,
The optical pickup device can be made thinner by supporting the objective lens holder so as to be movable vertically and horizontally via a focusing parallel plate nonone and a tracking parallel plate spring by a tracking moving body arranged parallel to the disk. , it is possible to reduce weight and cost, and it is also possible to reduce the distance between the optical axis and the outer surface of the optical big aladino housing, which has the effect of allowing the use of disk rotation motors and housings with large diameters. can get.

[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 is a schematic cross-sectional view taken along the line AA in FIG. 4 including the optical system, and FIG. 6 is a schematic cross-sectional view taken along the line B-B in FIG. 4. 1... Objective lens, 2... Lens tube, 6... Parallel plate spring for dragging, 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
...Objective lens holder, 12...Coil support piece,
13... Focus control coil, 14... Tracking control coil, 15... Focus/tracking magnetic circuit, 16... Optical pickup housing, 17... Parallel plate for focus 6, 18 ... Tracking moving body, 19... Parallel leaf spring for tracking. 15- 205-

Claims (1)

[Claims] 1. A coil support piece is provided protruding from one side of the objective lens holder on which the objective lens is mounted, and a square-shaped coil support piece is provided on the parallel side of the objective lens holder parallel to the second side and on the side of the coil support piece parallel to the parallel side. A focus control coil is provided around the objective lens holder with a gap between the two orthogonal sides of the objective lens holder, which are perpendicular to the parallel sides, and is fitted onto the focus control coil to perform tracking control on the upper and lower surfaces of the coil support piece. A permanent magnet is attached to the inner side of the opposing side of the magnetic body with a concave shape in the longitudinal section, and a permanent magnet is attached to the lower part of the other opposing side with a depth greater than the depth of the tracking control coil. An orthogonal portion of the focus control coil and a portion of the tracking control coil, which are orthogonal to the parallel side surfaces, are arranged in a gap between a pair of magnetic circuits in which a notch is formed and fixed to an optical pickup housing. Parallel leaf springs for focusing are installed on the upper and lower parts of the side surfaces and the upper and lower surfaces of the outer end of the tracking moving body, and tracking is applied to the side walls at both ends of the tracking moving body and both side walls of the optical pickup housing parallel to the tracking movement direction. A device for moving the objective lens vertically and horizontally of an optical pickup device, which is constructed by installing parallel plate springs.