JPS5968836A - Left/right/up/down shifter of objective lens for optical pickup device - Google Patents

Abstract

PURPOSE:To attain a miniature and small-sized device, by providing circumferentially a focus and a tracking control coil to a lens holder, arranging both coils to an air gap of a magnetic coil used in common to both coils and supporting freely movably the holder with a tracking moving body. CONSTITUTION:The focus control coil 13 and the tracking control coil 14 are arranged orthogonally in the same horizontal line to the objective lens holder 11 to reduce the height H2 in the Z axis. The magnetic circuit 15 in common use for focus and tracking is formed with a magnetic substance having recessed longitudinal cross section and a permanent magnet having rectangular lateral cross section. Since no magnetic circuit is arranged in the direction orthogonal to the tracking moving direction (X direction), the separating distance R2 between the optical axis and a housing 16 is less. A parallel plate spring 19 for tracking is erected on a base 16A the housing 16 and tracking parallel plate spring fitting pieces 18C, 18E of a tracking moving body 18 and supports elastically the moving body 18 to the X axis freely movably.

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 in particular, it focuses on an objective lens holder attached to an objective lens and a coil support piece protruding from the objective lens holder. A control coil and a tracking control coil are arranged around each other in directions orthogonal to each other, and both coils are placed in the gap between a pair of rectangular rod-shaped focusing fist tracking magnetic circuits, and are placed parallel to the disk. A parallel plate spring for focusing by a tracking moving body.

The present invention relates to an objective lens vertically and horizontally moving device for an optical pickup device that supports the objective lens holder via a tracking parallel plate plate so as to be movable vertically and horizontally.

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 disc 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.

In other words, a cylindrical permanent magnet 4 to which the objective lens 1 is fixed is mounted on a tracking parallel plate plate 3 mounted inside the lens barrel 2, and a voice coil 5 is protruded from the middle part of the lens barrel 2. , and a cylindrical permanent magnet 4.7I inch coil 5 is disposed inside the upper part of the storage tube 6, inside the near motor electromagnetic drive section Z, and inside the disc coil electromagnetic drive section 8 installed inside the middle part of the storage tube 6. Then, the lens barrel 2 is held inside the housing barrel 6 using a focusing parallel plate plate 9 having a circular hole in the center, and the current flowing through the coil 10 in the disc coil 5 and the linear motor electromagnetic drive unit 8 is The objective lens 1 is moved in the Z-axis direction or the X-axis direction depending on the direction and size of. In this way, the tracking drive section and the focus and drive section are arranged in two stages perpendicular to the disk D.

In this prior art, it is desirable that the parallel plate spring 3 for tracking has a small spring constant in order to widen the tracking operation range, and it is 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. Therefore, the height I-T of the optical pickup device in the Z-axis direction is small, resulting in the problem that the optical pickup device is 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 R1 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 consisting of the disc coil 5 and the voice coil electromagnetic drive unit 8 and the objective lens 1 are arranged concentrically, there is a problem that it is impossible to make the size smaller beyond a certain level. .

The present invention has been made by focusing on the problems of the prior art, and includes an objective lens holder on which an objective lens is attached, and a coil support piece protruding from the objective lens holder, including a focus control coil and a coil support piece. Tracking control coils are placed 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, and the tracking movement is 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 that it can move vertically and horizontally through a focus phase parallel plate and a tracking parallel plate.

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.

To briefly 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 that projects from one side surface 11A of the objective lens holder 11 and exerts a force. Height of coil support piece 12 I-1'J Height of objective lens holder 11 II: Set lower.

16 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.
, both orthogonal sides 11C, 1,L of the objective lens holder 11 that are orthogonal to the parallel side 11B (t or one side 11A)
D and a certain gap G between them. The height H3 of the focus control coil 16 is set lower than the height I of the coil support piece 12.

14 is a rectangular tracking control coil whose height is T.
-T4. The width W4 is the height of the focus control coil 16■
(3. Larger than width W3, focus control coil 13
The upper and lower surfaces 12B, 12 of the coil support piece 12 are fitted onto the outer surface of the coil support piece 12.
0 and perpendicular to the focus control coil 13. Objective lens holder 11 and coil support piece 12
By disposing the focus control coil 16 and the tracking control coil 14 in directions orthogonal to each other, the focus control coil 16 and the tracking control coil 1
4 are arranged on the same horizontal line, the height l-12 of the optical pickup device in the Z-axis direction is 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. Opposing magnetic material - side 1
A permanent magnet 15A is attached to the inside of 5B in the longitudinal direction, and the opposite side 1 of the permanent magnet 15A and the magnetic body
Between 5C and 5C is a gap 1 large enough to accommodate a focus control coil 16 and a tracking control coil 14.
5D is formed. Further, a notch 15E larger than the depth D4 of the tracking control coil 14 is formed in the lower part of the other opposing side 150 so that the tracking control coil 14 can be placed in the gap 15T. Opposing other side 15
The width W5 of the gap 0 is naturally smaller than the size of the gap 0, and the length L5 is the inner length of the focus control coil 13, which is 1.3.
The distance t between the end of the other opposing side 150 and the inside of the focus control coil 16 is set to be about 0.3 mm. The second surface of the other opposing side 150 that still has the notch 15E at the bottom (
The separation distance f between the inner side of the tracking control coil 14 (or lower surface) is approximately 1. Make it mm. By determining the separation distance of 1°f in this way, the tracking control coil 14. Even if an overcurrent flows through the focus control coil 16, the end of the focus control coil 13 and the other opposing side 150 may come into contact, or the top surface (or bottom surface) of the other opposing side 150 may come into contact with the tracking control coil 14. , the tracking control coil 14 does not move more than 0.3 mm, the focus control coil 13 does not move more than 1 order, and these coils 13 and 14 also serve as a stopper when returning the serze. There is no need to provide it. 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 hook-up housing 16.

The orthogonal portion 13A of the focus control coil 13 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. The one that still uses separate magnetic circuits for focus and tracking is a pair of focus/tracking magnetic circuits 15.
This reduces component costs and assembly costs.

Reference numeral 17 denotes a parallel plate spring for focusing, which is connected to the lower part of one side 11A of the objective lens holder 11 and the tracking moving body 1.
The objective lens holder 11 is moved from the outer end 18A in the focus movement direction (
It is elastically supported so that it can move freely in the Z-axis direction.

The tracking moving body 18 has an outer end portion 18A having a height slightly lower than the height H of the objective lens holder 11;
A horizontal piece 18B that projects from the center of the outer end 18A toward the objective lens holder 11 side, has a height lower than the height l-18 of the outer end 18A, and has an inverted T-shaped planar shape.
and a parallel plate mounting piece 18C for tracking with an inverted side shape protruding from both sides of the tip of the horizontal piece 18B. A through hole 18D is drilled therein, and a tracking girder plate nonone receiving piece 18E is provided protruding from the upper outer surface of the outer end portion 18A. 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 parallel plate spring, the height of which is greater than the height of the outer end 18A I8, and the tracking parallel plate spring mounting pieces 180, 18 of the tracking moving body 18.
E and base 16AVc of optical pickup housing 16
It is erected and elastically supports the tracking moving body 18 so as to be movable in the tracking movement direction (X-axis direction) from the base 16A.

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 16 is integrated with the objective lens holder 11, and the focus control coil 16 is integrated with the objective lens holder 11.
Since it is elastically supported by 7, it moves in the vertical direction (Z-axis direction). Therefore, the objective lens 1, which is integrated with the focus control coil 13 and 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 16.

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 orthogonal to each other, the tracking control coil 14 is moved in the left/right direction (X-axis direction) based on Fleming's left hand rule.
Receive force. Then, tracking control coil 1
4 is integrated with the objective lens holder 11 and is elastically supported in the left-right direction (X-axis direction) by a tracking parallel plate spring 19 attached to the tracking moving body 18 via a focusing parallel plate spring 17. Move in the left/right direction (X-axis direction). Therefore, the objective lens 1, which is integrated with the tracking control coil 14, the coil support piece 12°, and the objective lens holder 11, also moves in the left-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 splitter 21 and the collimator lens 22.1 as shown in FIG.
/4 wavelength plate 26.90° 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 four-split optical sensor via 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,
By supporting the objective lens holder so as to be movable vertically and horizontally via a focusing parallel plate spring and a tracking parallel plate spring by a tracking moving body arranged parallel to the disk, the optical pickup device can be made thinner.
It is possible to reduce weight and cost, and because it is possible to reduce the distance between the optical axis and the outer surface of the optical pickup housing, it is possible to use a disk rotation motor housing with a larger diameter. It will be done.

[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 invention, and FIG. 4 is an embodiment of the 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. DESCRIPTION OF SYMBOLS 1... Objective lens, 2... Lens barrel, 6... Parallel plate 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, 1
DESCRIPTION OF SYMBOLS 1... Objective lens holder, 12... Coil support piece, 13... Coil for focus control, 14... Coil for tracking control, 15... Magnetic circuit for both focus and tracking, 16... Light Pickup housing, 17...Parallel plate spring for focus, 18...
Tracking moving body, 19... Parallel plate spring for tracking. 15- 211-

Claims (1)

[Claims] 1. When the objective lens is attached, a coil support piece is provided protruding from one side of the objective lens holder, and the parallel side of the objective lens holder parallel to the second side and the coil support piece parallel to the parallel side are provided. A rectangular focus control coil is provided on the side surface with a gap between both orthogonal side surfaces of the objective lens holder that are orthogonal to the parallel side surfaces, and is fitted onto the focus control coil and tracked on the upper and lower surfaces of the coil support piece. A control coil is installed around the magnetic body, and a permanent magnet is attached to the inside of the opposing side in the longitudinal direction, and a permanent magnet is attached to the bottom of the other opposing side from the depth of the tracking control coil. An orthogonal part of the focus control coil and a part of the tracking control coil, which are orthogonal to the parallel side surfaces, are disposed in a gap between a pair of magnetic circuits in which a large notch is formed and fixed to the optical pickup housing. - Parallel plate 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 parallel plate springs for tracking are installed upright on the bases of the tracking moving body and the optical shock absorber. A device for moving the objective lens vertically and horizontally of the optical pickup device