JPS58111135A - Vertical and horizontal moving device for objective lens of light pick-up device - Google Patents

Abstract

PURPOSE:To reduce the thickness of the titled device by arranging a tracking driving part and a focus driving part on the same line to a disc and shifting an objective lens from the center of the focus driving part in the inner circumferential direction of the radius of the disc. CONSTITUTION:The objective lens 1 is shifted from the center position of the focus driving part consisting of a focus driving permanent magnet 11 and a focus controlling round coil 14 in the inner circumferential direction of the radius of the disc D. A tracking driving permanent magnet 18 is fixed on an external frame and a tracking controling square coil 17 is inserted into a gap part 18F. Thus the tracking driving part consisting of the permanent magnet 18 and the square coil 17 is in parallel with the disc D and is arranged on the same line as the focus driving part. Consequently the size of the light pick-up device is reduced in the Z axial direction, reducing the thickness of the device.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for vertically and horizontally moving an objective lens of an optical pickup device, and in particular, when a tracking drive unit and a focus drive unit are arranged parallel to and on the same line with respect to a disk, it is possible to move the objective lens to a book. The present invention relates to a device for vertically and horizontally moving an objective lens of an optical pickup device, which is arranged to be shifted from the center position of a focus drive unit in the radial direction of the disk.

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 a disc coil electromagnetic drive, and tracking (X-axis direction) control is performed by a linear motor electromagnetic drive, and the object to be driven is the objective lens 1. In other words, the inside of the lens barrel 2 A cylindrical permanent magnet 4 to which an objective lens 1 is fixed is mounted on a tracking parallel plate plate 6 attached to the cylindrical permanent magnet, and a Zeiss coil 5 is protruded from the middle part of the lens barrel 2. 4. The ZEIS coil 5 is installed inside the upper part of the housing tube 6, inside the near motor electromagnetic drive section 7, and in the discoil electromagnetic drive section 8 installed inside the middle part of the housing tube 6.
The lens barrel 2 is held inside the housing barrel 6 using a parallel plate for focusing 9 which is disposed inside and has a circular hole in the center. The objective lens 1 is moved in the two-axis direction or in the X-axis direction depending on the direction and magnitude of the current flowing therein. In this way, the tracking drive section and the focus drive section are arranged in two stages perpendicular to the disk.

In this prior art, it is desirable that the tracking parallel plate spring 3 has a small spring constant in order to widen the tracking operation range, and it is also necessary to have a somewhat large spring constant in order to be self-supporting. Furthermore, if it is to be resistant to temperature changes, it is preferable to use metal. Taking all of the above into account, long metal plates are generally used.

Therefore, the size l1 of the optical pink-up device in the Z-axis direction
td is large, and as a result, there is a problem in that the optical big amplifier device is large and heavy.

In addition, when the 7-Using of the disk rotation drive motor and the pickup body are on the same side, if the inner circumference of the disk is to be pink-amplified, the separation distance R1 between the optical axis and the outer surface of the big amplifier body in the disk radial direction must be as small as possible. However, since the objective lens 1 and the focus drive section composed of the Zeiss coil 5 and the disc coil electromagnetic drive section 8 are arranged concentrically, there is a problem that the size cannot be reduced beyond a certain level.

The present invention was made by focusing on the problems of the prior art, and it consists of arranging the tracking drive section and the focus drive section parallel to and on the same line with respect to the disk, and positioning the objective lens at the center position of the focus drive section. It is an object of the present invention to solve the above-mentioned problem by arranging the discs so as to be shifted further in the direction of the inner circumference of the disk radius.

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 configuration will be described. Reference numeral 11 is a permanent magnet for focus driving, and is a cylindrical Sugibayashi. Focus drive permanent magnet 11
are a ring-shaped permanent magnet piece 11A and a permanent magnet piece 11A.
A permanent magnet piece 11A and a larger ring-shaped magnetic piece 11B are fixed to the upper surface of the permanent magnet piece 11A.

The magnetic piece 11B is composed of a tube flange-shaped magnetic piece 11C fixed to the lower surface of the permanent magnet piece 11A.

A gap 11D is formed between the holes 110. A focus drive permanent magnet 11 is fixed to an outer frame 12. 1
6 is a vertically moving part, which is a cylinder. A round coil 14 for focus control, which is disposed in the gap 11D of the permanent magnet 11 for focus drive, is protrudingly provided in the middle part of the vertical moving part 16, and four arms radially extend from the circumferential surface of the upper and lower ends. 13A
are provided protrudingly, and through holes 13B are bored at the upper and lower ends in parallel to the tracking movement direction (X-axis direction). Arm 1
3A forms an angle of 45 degrees with the tracking movement direction (X-axis direction), and its length is larger than the radius of the focus drive permanent magnet 11. Further, the distance between the through holes 13B is greater than the height of the focus drive permanent magnet 11. 15
are parallel plate springs for tracking and are attached to the left, right, upper and lower arms 13A that are perpendicular to the first through hole 13BK'. 1
A shaft 6 is fixed to the tracking parallel plate spring 15 by welding or the like through a through hole 15A and a through hole 13B formed above and below the center of the tracking parallel plate spring 15. A lens barrel 1A on which the objective lens 1 is mounted is fixed to the left end of the shaft 16. As shown in FIG. 4, the objective lens 1 is disposed offset from the center position of the focus drive unit, which is composed of the focus drive permanent magnet 11 and the focus control round coil 14, in the inner radial direction of the disk D. There is. Therefore, the separation distance R between the optical axis and the outer surface of the pink amplifier body can be made smaller than in the prior art. A square coil 17 for tracking control is fixed to the right end of the shaft 16. 18 is a permanent magnet for tracking drive, and two permanent magnet pieces 18A, 1
8B, a flat T-shaped magnetic piece 18C sandwiched between the 8 poles of the two permanent magnet pieces 18A and 18H, and a flat T-shaped magnetic piece 18C fixed to the N pole side of the two permanent magnet pieces and a flat surface. It is composed of letter-shaped magnetic pieces 18D and 18B.

A gap 18F is formed between the magnetic piece 180 and the magnetic piece 18D and between the magnetic piece 18C and the magnetic piece 18g. The tracking drive permanent magnet 18 is fixed to the outer frame 12, and the tracking control square coil 17 is inserted into the gap 18F. In this way, the tracking drive section consisting of the tracking drive permanent magnet 18 and the trunking control rectangular coil 17 is arranged parallel to the disk D and on the same line as the focus drive section. Therefore, the large formula H2 in the two-axis direction of the optical pink amplifier device becomes smaller,
The optical pickup device can be made thinner.

Reference numeral 19 denotes a parallel plate spring for focusing, which is inserted between the outer frame 12 and the upper surface 130 of the vertically moving section 13 and between the outer frame 12 and the lower surface 13D of the vertically moving section 13 to elastically support the vertically moving section 16. . In addition, the square coil 17 for tracking control
The height is determined so that the tracking control rectangular coil 17 does not come into contact with the magnetic piece 180 of the tracking drive permanent magnet during focus movement (Z-axis direction).

Next, the effect will be explained. When the focus error signal or the tracking error signal is zero, the focus control round coil 14 or the tracking control square coil 1
No current flows through the lens 7, 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 round 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 round coil 14 receives a force in the vertical direction and the CZ axis direction based on Fleming's left hand rule. The focus control round coil 14 is integrated with the vertical moving unit 13 and is elastically supported by the focus parallel plate nonone 19, so that it can be rotated in the vertical direction (Z
axial direction]. Therefore, the focus control round coil 14 and the vertical moving section 13. The objective lens 1, which is integrated through the shaft 16, 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 round coil 14. Next, when there is a tracking error signal, a current flows through the tracking control rectangular coil 17. Since the direction of this current and the direction of the magnetic flux from the tracking drive permanent magnet 18 are perpendicular to each other, the tracking control rectangular coil 17 is moved in the left-right direction (
Force is received in the X-axis direction). The square coil 17 for tracking control is connected to the shaft 16. The arm 13A of the vertical moving part 13 is integrated with the tracking parallel plate plate 15.
Since it is elastically supported in the left-right direction (X-axis direction) by a tracking parallel plate spring 15 attached to the , it moves in the left-right direction (X-axis direction). Therefore, the objective lens 1, which is integrated with the tracking control rectangular coil 17 and the shaft 16, also moves in the left-right direction (X-axis direction). The direction and amount of movement are determined by the direction and magnitude of the current flowing through the tracking control rectangular coil 17. Note that the focus error signal and the tracking error signal are generated by the semiconductor laser 20 as shown in FIG.
Laser beam total collimator lens 21. Polarizing beam splitter 22° 174 wavelength plate 23.9 [1° deflection mirror 24
．． The reflected light from the disk D is returned to the polarizing beam splitter 22 in the reverse order, deflected by 9o0, and guided to a four-split sensor through a number of light shielding plates and converging lenses (not shown in the figure).

As explained above, the present invention arranges the tracking drive section and the focus drive section parallel to the disk and on the same line, and also shifts the objective lens from the center position of the focus drive section in the inner circumferential direction of the disk. By arranging this, the optical pickup device can be made thinner.

This provides the effect that the distance between the optical axis and the outer surface of the optical pickup device can be reduced.

[Brief explanation of drawings]

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 exploded perspective view of a tracking drive unit of the prior art. It is a view of the Imperial Palace taken from A'-A in FIG. 3. DESCRIPTION OF SYMBOLS 1... Objective lens, 2... Lens barrel, 3... Tracking phase parallel plate/piece, 4... Cylindrical permanent magnet, 5
... Zeiss coil, 6... Storage cylinder, 7... Linear motor electromagnetic drive section, 8... Discoil electromagnetic drive section,
9... Parallel plate spring for focus, 10... Coil,
DESCRIPTION OF SYMBOLS 11... Permanent magnet for focus drive, 12... Outer frame, 13... Vertical movement part, 14... Round coil for focus control. 15...Parallel plate for tracking, 16...Shaft, 17...Square coil for tracking control, 1
8... Permanent magnet for tracking drive, 19... Parallel plate spring for focusing, 20... Semiconductor laser, 21.
... Collimator lens, 22... Polarizing beam splitter.

Claims (1)

[Scope of Claims] 1. A ring-shaped focus drive permanent magnet consisting of a permanent magnet piece and a magnetic piece that are fixed to an outer frame. A round coil for focus control is disposed in the gap of the focus drive water magnet, and four arms protrude radially from the circumferential surface of the upper and lower ends. A vertical moving part with parallel through holes drilled therein, a tracking parallel plate spring attached to the left and right upper and lower arms perpendicular to the through hole, and a through hole drilled in the center top and bottom of the tracking parallel plate spring. ?, two shafts that pass through the through holes and are fixed to the tracking parallel plate nonones, and a lens barrel to which an objective lens fixed to the left end of the shaft is attached.At the right end of the shaft. A fixed square coil for tracking control, a permanent magnet for tracking drive consisting of a permanent magnet piece and a magnetic piece that are partially inserted into the hollow part of the square coil for tracking control and fixed to an outer frame, and an outer frame. A device for vertically and horizontally moving an objective lens of an optical pickup device, comprising a parallel plate spring for focusing inserted between an upper surface and a lower surface of the vertically moving section to elastically support the vertically moving section.