JPS60212837A - Objective driving device for optical disk player - Google Patents

Abstract

PURPOSE:To form a highly accurate small-sized objective driving device for optical disk player, by fixedly providing magnets constituting parts of a motor for driving an objective holding the inside arc-shaped grooves in yokes and arranging the pair of yoke symmetrically about the supporting shaft of the objective holding tube. CONSTITUTION:A pair of yokes 10 and 11 of a linear motor for driving an objective holding tube which holds an objective 7 and is equipped with a coil 15 for focussing and coil 16 for tracking adjustment at its outer peripheral surface in the direction of optical axis, and a pair of magnets 12 and 13 are provided symmetrically about the supporting shaft 2 of the objective holding tube 4 which is set in the direction normal to the tracing direction and the rotating center of the tube 4. The yokes 10 and 11 and magnets 12 and 13 together with the coils 16A and 16B for tracking adjustment constitute a motor which rotates the objective holding tube 4 around the suporting shaft 2 and the magnets 12 and 13 are respectively put in arc-shaped grooves 9A and 9B of the yokes 10 and 11 so as to miniaturize this device.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an optical pickup device for a disk player, and more particularly to an improvement of an objective lens drive device having an automatic focusing adjustment mechanism and an automatic tracking adjustment mechanism.

[Background of the invention]

An objective lens device used in an optical disc player has an automatic focusing adjustment mechanism that moves the objective lens in the optical axis direction in order to focus the light beam on the disc surface, and an automatic focusing adjustment mechanism that moves the objective lens in the tracking direction perpendicular to the optical axis. It is known to be equipped with an automatic tracking adjustment mechanism for correctly tracking the information trunk of the entire disk surface of the displaced and focused source beam. In this conventionally known objective lens driving device, for example, an objective lens holding cylinder is rotatably attached to a support shaft and slidably in a thrust direction, and the objective lens is held eccentrically from its axis. Some lenses perform tracking adjustment by rotating the lens holding cylinder, and others perform focusing adjustment by sliding it in the thrust direction.

The adjustment mechanism that performs the tracking adjustment and focusing adjustment includes a first coil for focusing wrapped around the outer periphery of the objective lens holding tube, and a plurality of rectangular tracking adjustment coils attached to the outer periphery of the first coil. and a cylindrical magnet provided on the outer periphery of the holding cylinder and held vertically by the pair of yokes. The objective lens holding tube is driven in the thrust direction by the first coil and the pair of yokes,
Further, the objective lens holding cylinder is configured to be driven in the radial direction by the second coil and the pair of yokes.

However, in the conventional objective lens driving device described above, it is difficult to shorten the width in the tracking direction because the thickness in the optical axis direction is large and the magnet surrounding the objective lens holding cylinder is cylindrical. .

Therefore, not only does the external size of the drive device become large, but also a large space in the tracking direction for moving the objective lens device must be secured, which has the drawback of hindering miniaturization and thinning of the disk player. Furthermore, if the diameter of the cylindrical magnet is made smaller, the diameter of the objective lens holding cylinder is also made smaller, which has the disadvantage that the eccentricity of the objective lens is shortened and the sensitivity of tracking adjustment is reduced.

[Purpose of the invention]

Does the present invention have any disadvantages of the above-mentioned conventional devices? The purpose of the present invention is to provide an objective lens driving device that is small in size and highly accurate.

[Summary of the invention]

In order to achieve all of the above objectives, the entire objective lens is retained and a focusing coil is attached to the outer circumferential surface for tracking! iM
an objective lens holding tube having an I adjustment coil; a supporting means including a support shaft provided in parallel to the optical axis of the objective lens for slidably supporting the objective lens holding tube; and a focusing coil. In an optical pink-up device that includes a yoke that sandwiches a tracking adjustment coil and a tracking adjustment coil from the inside and outside of an objective lens holding tube, and a magnet fixed to this yoke, a pair of yokes each having an arcuate groove is attached to the yoke? and arranging each yoke symmetrically with respect to the spindle in a direction connecting the inside of the objective lens and the center of the spindle,
The technical key point is to insert an objective lens holding cylinder into the arcuate groove of each yoke, and to fix an arcuate magnet magnetized in the radial direction in the inner groove of the arcuate groove. .

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail based on all attached aspects.

Fig. 1 is a perspective view showing the configuration of an embodiment of the present invention, Fig. 2 is an assembled perspective view of the embodiment of the invention, Fig. 3 is a vertical sectional view of Fig. 2, and Fig. 4 is a perspective view of the embodiment of the present invention. FIG. 3 is a sectional view taken along line A-A in FIG. 3;

In FIG. 1, an oval-shaped plywood board 1 formed by cutting both sides of a disc parallel to each other has a support shaft 2 fixed at its center, and a support shaft 2 on the base plate 1 extends from the support shaft 2 A light beam passage hole 3 through which the light beam passes is provided at a spaced apart position.

The objective lens holding cylinder 4 is formed into a double cylindrical shape with an inside and outside as shown in FIG. It is rotatably and slidably supported by the support shaft 2.

Further, the upper surface 314CK, which is fully connected to the inner cylinder part 4A and the outer cylinder part 4B, is provided with an objective lens 7 eccentrically from the rotation center of the objective lens holding cylinder 4, and passes through the light beam passage hole 3 on the base plate l. The light beam is the objective lens 7'! ! - configured to be focused through. Further, on the upper surface portion 4C of the objective lens holding cylinder 4 on the opposite side from the objective lens 7 with respect to the center of rotation, a plate spring 8 extending in the radial direction and for holding a neutral point is fixedly provided. This leaf spring 8 maintains a neutral point for tracking adjustment of the objective lens 7, and at the same time
It is constructed to maintain a weight balance with the objective lens 7.

Further, on the base plate 1, arc grooves 9A, 9Bi formed around the support shaft 2 are sandwiched between the arc inner cylinder parts 10A, IIA and the arc outer cylinder parts 10B, IIB? A pair of fan-shaped yokes 10 and 11 each having a U-shaped cross section are fixed symmetrically to the support shaft 2 and in a direction substantially perpendicular to the tracking direction. Arc-shaped magnets 12 and 13 magnetized in the radial direction are fixed to the inner circumferential surfaces of the arcuate outer cylindrical parts 10B and 11B, respectively, and the magnets 12 and 13 are
Together with the yokes 10 and 11, they are formed into a fan shape that forms approximately 90° in the circumferential direction. The outer cylinder part 4B of the objective lens holding cylinder 4 is inserted as shown in FIG. 12. Each line of magnetic force in 13 is connected to the outer cylinder part 4B of the objective lens holding cylinder 4? It is configured to cross in the radial direction. In addition, a notch 10a is provided in the arcuate inner cylinder part 10A of one yoke 1° so that the peripheral light of the original beam can pass through, and in the center of the upper surface of the arcuate outer cylinder part of the other yoke 11, A retaining pin 14 having a slot 14a that engages with the free end of the neutral point retaining plate spring 8 provided on the upper surface portion 4C of the objective lens retaining cylinder 4 is implanted.

On the other hand, a focusing coil 15 is wound around the outer periphery of the outer cylinder portion 4B of the objective lens holding cylinder 4, and four tracking adjustment coils 16 wound in a rectangular shape are provided on the focusing coil 15. There is. As shown in FIG. 4, this tracking adjustment coil 16 has both ends i (+12a, 12b, 13a
, 13b, one half 16A is located in the arcuate grooves 9A, 9B of the yokes 10 and 11, and the other half 16
B is the space P3VC between the yoke 10 and another yoke 11
It is set up so that it is located.

Note that the focusing coil 15. A linear motor that drives the objective lens holding cylinder 4 in the optical axis direction with a pair of yokes 10 and 11 and a pair of magnets 12 and 13t is m1.
Et, and the tracking adjustment coil 16A
, 16B, a rotation motor for rotating the objective lens holding cylinder 4 around the supporting shaft 2 with a pair of yokes 10 and 11 and a pair of magnets 12 and 13 is constructed. In this case, the magnets 12 and 13 are respectively placed in the arcuate grooves 9A of the yoke 10 and 11.
.

9B, the height t of the conventional objective lens driving device can be lowered.

In addition, the yoke 10.11 and the magnets 12 and 13F'i
In both cases, both sides of the cylinder are cut out with segments mIEj, -s, so the width of the device in the tracking direction is as shown in Fig. 4.
It can be shortened to a size equal to the outer circumferential diameter of 4.

Since the embodiment shown in FIGS. 1 to 4 is constructed as described above, the surface of the rotating disk (not shown) is oscillated, and the surface of the disk is moved from the position where the light beam is focused by the objective lens 7Vc. When is displaced in the optical axis direction, the displacement is immediately detected by a focus detection device i1 (not shown), and a current is supplied to the focusing coil 15 in accordance with the detection signal. When a current flows through the focusing coil 15, a driving force is generated in the optical axis direction of the coil 15, and the objective lens 7 is moved along with the objective lens holding cylinder 4 in the optical axis direction Kffi. At that time, is the tip of the neutral point holding plate spring 8 located within the slot 14a of the engagement pin 14? slide. In addition, since the weight of the objective lens 7 and the neutral point holding plate spring 8 is balanced with respect to the center of the objective lens holding tube 4, the tilting of the objective lens holding tube 4 is suppressed to a minimum, and the objective lens 7 is follows the disk surface faithfully.

The objective lens holder @< moves in the optical axis direction, and the objective lens 7
When the distance between the light beam and the disk surface reaches a predetermined value and the focus position of the light beam matches the disk surface, the detection signal from the focus detection device becomes F, the current flowing through the focusing coil 15 becomes zero, and focusing Coil 15F
'i Stop at that position.

Therefore, the objective lens 7 is automatically displaced in accordance with the deflection of the disk surface, and can constantly focus the light beam on the disk surface.

On the other hand, when the light beam focused by the objective lens 7 is displaced from the center of the track width on the scanning surface of the disk, the displacement is detected by a detection device (not shown), and the next current is adjusted according to the detection signal. The current flows to the maintenance coil 16. When a current flows through the tracking adjustment coil 16 wound in a square shape on the outside of the objective lens holding tube 4, a rotational torque is generated in one outgoing path 16A (see FIG. 4) of the trunking adjustment coil 16 that intersects with the magnetic field. ? Rotational torque is generated, but on the other return path 16B that does not intersect with the magnetic field? Does not occur. Therefore, the torque generated in the outward path 16A directly becomes rotational torque, and the objective lens holding cylinder rotates in either the left or right direction depending on the direction of the flowing current. Therefore, the objective lens 7 is driven in the tracking direction, and tracking adjustment is automatically performed.

Note that the present invention is not limited to the above-mentioned embodiments, and for example, the arcuate cylinder portions 10A, 10B, -j or IIA, ]IB' sandwiching the arcuate grooves 9A, 9B of the yoke 10.11.
ji7 After separating and forming, they are combined into one circular arc groove 9A, 9B'! r may be formed.

〔Effect of the invention〕

As described above, according to the present invention, the foundation stone forming part of the molding that drives the objective lens holding cylinder is fixed in the circular arc groove provided in the yoke, so that the height of the objective lens driving device is reduced. In addition, the pair of yokes and the objective lens holding tube are arranged symmetrically with respect to the supporting shaft that supports them so that they can slide all the way around, so that the width of the device in the tracking direction is approximately equal to the outer diameter of the objective lens holding tube. The width K can be shortened to a new width K, and the entire device can be made compact and compact.

In addition, since the entire outer diameter of the objective lens holding tube can be expanded to an outer diameter that is approximately equal to the width in the tracking direction, the amount of deviation of the objective lens provided on the upper surface side of the objective lens holding tube can be increased. It is possible to increase the total sensitivity of the 9 tracking adjustments.

[Brief explanation of the drawing]

Fig. 1 is an exploded perspective view showing the components of an embodiment of the present invention;
The figure is an assembled perspective view of Figure 1, Figure 3 is a vertical sectional view of Figure 2,
FIG. 4 is a sectional view taken along the line AA in FIG. 3. [Lord g! ! Explanation of part symbols] 1... Base plate, 2... Support shaft, 4... Objective lens holding tube. 7... Objective lens, 8... Leaf spring for holding the neutral point. 9A/9B...Circular groove, 10-11...Yoke. 10A-11A...Circular inner cylinder part. 10B/IIB...Circular outer cylinder part, ]4...Engagement pin. 15...Focusing coil. 16...Toratsukifugu adjustment coil Applicant: Takashi Watanabe, Agent, Nippon Kogaku Kogyo Co., Ltd. Figure 1 Figure 3 Figure O

Claims (3)

[Claims] (1) An objective lens holding tube that holds the entire objective lens and has a focusing coil and a tracking adjustment coil on its outer peripheral surface; a support means including a support shaft provided parallel to the optical axis of the objective lens; a yoke sandwiching the focusing coil, the tracking adjustment coil, and the lens holding cylinder from the inside and outside; and a yoke fixed to the yoke. In an optical big amplifier device equipped with a magnet and metal,
All of the yokes are separately formed as a pair of yokes each having an arcuate groove, and each yoke is arranged symmetrically with respect to the support shaft in a direction connecting the lens center of the objective lens and the center of the support shaft. An optical disc player characterized in that the objective lens holding cylinder is fully inserted into the arcuate groove, and a radially magnetized arcuate magnet is fixed to the inner wall of each of the arcuate grooves. Relative object lens drive device. (2) The yoke (10, l1) and the magnet (12
, 13) are located at two locations perpendicular to the tracking direction and symmetrical with respect to the center of rotation of the objective lens holding tube. Objective lens drive device for disc players. (3) One of the pair of yokes (11JKV′i), an elastic member for holding the neutral point (11JKV'i) for holding the neutral point of the objective lens (7) in the tracking direction and balancing the weight with the objective lens (7); 8) An objective lens drive device for an optical TiSF player according to claim 1 or 2, characterized in that a retaining pin (16) that engages with the free end is provided. .