JPH1048499A - Pickup device for optical information reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily make the structure of a pickup device simple, smaller in size, and low in cost by providing the device with four pieces of slender flexible members of a cantilever from which are flexible in either of the optical axis direction and the perpendicular direction of the an objective lens, and support the objective lens at the free ends. SOLUTION: The respective free ends of the flexible members 22 fixed like the cantilever to a fixing part 20 are coupled with coupling members to the outer peripheral surface of cylindrical part 14. The four flexible members 22 are respectively approximately parallel and are so arranged that their sections face the same direction. The coupling points of the flexible members 22 and the cylindrical part 14 are so positioned that the straight lines connecting the coupling points pass the centroid of an optical system 11. The flexible members 22 are deflected in a focusing direction Z and a tracking direction X on occation and the optical system 11 is driven parallel in both directions without rotating when respective adequate currents are supplied to respective driving coils 13, 17 and 18 during the reading action of the pickup device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pickup device in an optical information reading device.

[0002]

2. Description of the Related Art In an optical information reading apparatus, a disk such as a video disk or a digital audio disk as an information recording medium has fine pits (dents) formed on its surface as spiral tracks in accordance with an information signal. Thus, the information signal is recorded. When reproducing such a disc, the disc is irradiated with spot light while rotating the disc at a predetermined number of revolutions, and a change in the intensity of the reflected light or transmitted light is converted into an electric signal, which is used as an original information signal. It is something to play.

In the reproduction of the disk, the irradiation light must be accurately focused on the recording surface of the disk. Therefore, the position control (focus servo) in the direction perpendicular to the recording surface of the optical system, that is, in the focus direction, is required. In addition, the irradiation light must always accurately follow the recording track, and therefore, it is necessary to control the irradiation light in the radial direction of the disk, that is, in the tracking direction (tracking servo).

For this purpose, in a reading pickup device in an optical information reading device, a support mechanism for movably supporting an optical system for irradiating a spot light for reading information on a disk recording surface in a focusing direction and a tracking direction, a focusing error, And a driving device for driving the optical system in the focusing direction and the tracking direction according to the signal and the tracking error signal.

[0005] Various such pickup devices have been proposed in the past, one example of which is shown in FIG. As shown, an optical system 4 having an objective lens 2 and a cylindrical portion 3 is fixed to a free end of a cantilever-like member 1 having one end fixed. The cantilever-shaped member 1 is disposed in parallel with a disk recording surface (not shown), and has a leaf spring portion 5 that is flexible only in the optical axis direction of the optical system 4, that is, in the focus direction Z. And a leaf spring portion 6 that is flexible only in a tracking direction X perpendicular to the tracking direction. A driving coil 8 in the focus direction Z is wound around a circular bobbin 7 fixed below the cylindrical portion 3, and a pair of bobbins 9 provided on the cylindrical portion 3 so as to protrude in the tracking direction X. Has the tracking direction X
The driving coil 10 is wound. Further, a magnetic circuit (not shown) for applying an electromagnetic driving force to each of the driving coils 8 and 10 is provided. When an appropriate current is supplied to the driving coils 8 and 10, the leaf springs 5 and 6 bend in the focusing direction Z and the tracking direction X, respectively, and the optical system 4 is driven.

[0006]

In a conventional pickup device of an optical information reading apparatus, a support mechanism of an optical system is composed of two support mechanisms having a degree of freedom in only one of a focus direction and a tracking direction. It is configured by a combination. Therefore, the structure was complicated, and it was difficult to manufacture. In addition, since the two support mechanisms are combined, there are disadvantages that a large volume is required, miniaturization is difficult to achieve, and parasitic resonance easily occurs.

The present invention has been made in view of the above points, and an object of the present invention is to provide a pickup device which has a simple structure, is easily miniaturized, and is inexpensive.

[0008]

According to the present invention, there is provided a pickup apparatus for an optical information reading apparatus, wherein a holding member for holding an objective lens is movable in an optical axis direction and a direction perpendicular thereto, and the optical axis of the objective lens is adjusted. A support mechanism for supporting the disk so as to be perpendicular to the disk surface extends substantially perpendicularly to the two directions, and is flexible in both of the two directions over its entire length and is free at the free end. And four elongated cantilevered flexible members supporting the objective lens.

[0009]

According to the present invention, the support mechanism of the holding member of the pick-up device of the optical information reading device is extended in four directions perpendicular to the optical axis direction and two directions perpendicular to the optical axis direction. Since the cantilever-shaped elongated flexible member is used, a single support mechanism can be configured to have a degree of freedom in the above-described two directions, and the support mechanism can be reduced in size as compared with the related art.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A pickup device according to the present invention will be described below with reference to the accompanying drawings. As shown in FIGS. 1 and 2, a driving coil 13 in the optical axis direction of the optical system 11, that is, in the focus direction Z is provided on the outer periphery of the circular bobbin portion 12 provided in the optical system 11 in the circumferential direction. It is wound. A pair of substantially rectangular bobbin parts 15 and 16 are provided on the cylindrical part 14 of the optical system 11 so as to protrude in a direction perpendicular to the optical axis direction, that is, in the tracking direction X.
Drive coils 17 and 18 in the focus direction X are wound around the bobbin portions 15 and 16, respectively. Also,
Reference numeral 19 denotes an objective lens fitted in the cylindrical portion 14 and constitutes a part of an optical system together with the cylindrical portion 14.

On the upper and lower surfaces of the fixed portion 20, four grooves 21 are provided at right angles to the focus direction Z and the tracking direction X, each of which is two in total. One end of each of the four longitudinal flexible members 22 is fitted into the four grooves, and is fixed with an adhesive or the like. The flexible members 22 are made of, for example, beryllium copper or the like, and are formed so that four of them have substantially the same length and a cross section perpendicular to the longitudinal direction is rectangular.

As described above, each free end of the flexible member 22 fixed in a cantilever shape to the fixing portion 20 is connected to the outer peripheral surface of the cylindrical portion 14 by the connecting member 23, The flexible members 22 are arranged so that they are substantially parallel and their cross-sections face the same direction. As is clear from FIG. 2, the connection points between the flexible member 22 and the cylindrical portion 14 are defined by straight lines AA and BB connecting the connection points with the center of gravity (G
(Point).

Each of the driving coils 1
A magnetic circuit (not shown) for applying an electromagnetic driving force to each of the driving coils corresponding to 3, 17 and 18
Is provided.

During the reading operation of the pickup device, when an appropriate current is supplied to each of the driving coils 13, 17, and 18, the flexible member 22 flexes in the focus direction Z and the tracking direction X as needed, causing the optical system 11 to flex. It is driven in both directions. .

Here, as described above, by making the straight line connecting the connecting point between the flexible member 22 and the cylindrical portion 14 pass through the center of gravity of the optical system 11, the optical system 11 rotates. Instead, they are driven parallel to the tracking direction X or the focus direction Z.

The cross-sectional shape of the flexible member 22 is not limited to the rectangular shape as described above, but may be, for example, a circular shape or a square shape. However, by making the cross-sectional shape rectangular, the cross-sectional dimensions in the focus direction Z and the tracking direction X are changed, and the bending rigidity of the flexible member 22 in each of the above directions can be appropriately determined. 2
The low-band resonance frequency in each of the two directions can be any convenient frequency. If the cross-sectional areas are the same, the torsional rigidity can be maximized by making the cross-sectional shape rectangular.

On the other hand, when the cross section is circular or square, there is no directionality of the cross sectional shape, so that it is possible to form, for example, only by cutting a commercially available wire into an appropriate length, thereby simplifying the assembling work and Costs can be reduced.

[0018]

As described above in detail, in the pickup device of the optical information reading apparatus according to the present invention, the support mechanism of the holding member for the objective lens is provided in two directions, the optical axis direction and the direction perpendicular to the optical axis direction. A substantially cantilever-like elongated flexible member that is substantially perpendicular to the body and is flexible in any of the two directions over substantially the entire length thereof and supports the objective lens at a free end portion. It is configured. Therefore, a single support mechanism can be configured to have a degree of freedom in the two directions, and the support mechanism can be downsized as compared with a conventional pickup device. Further, in the pickup device of the optical information reading device according to the present invention, the above-mentioned elongated flexible member can be formed by merely cutting a commercially available wire into an appropriate length, thereby reducing costs. It is easier.

[Brief description of the drawings]

FIG. 1 is a perspective view of a pickup device of an optical information reading device according to the present invention.

FIG. 2 is a sectional view of a pickup device of the optical information reading device according to the present invention.

FIG. 3 is a diagram showing a pickup device of a conventional optical information reading device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Optical system 12, 15, 16 Bobbin part 13, 17, 18 Driving coil 14 Cylindrical part 19 Objective lens 20 Fixed part 22 Flexible member

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[Procedure amendment]

[Submission date] June 18, 1997

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Name of invention

[Correction method] Change

[Correction contents]

Patent application title: Pickup device in optical information reading device

Claims (1)

[Claims] 1. An objective lens for irradiating a recording surface of a recording medium with light, an objective lens holding member for holding the objective lens, and an objective lens having an optical axis direction of the objective lens and an optical axis direction. A pickup device including a driving unit that drives the objective lens in a vertical direction, and a support mechanism that movably supports the objective lens in the optical axis direction and in a direction perpendicular to the optical axis, wherein the driving unit includes the objective lens A focus coil and a plurality of tracking coils fixed to a holding member, and a magnetic circuit for applying a magnetic flux to the focus coil and the tracking coil, wherein the support mechanism includes the optical axis direction and the optical axis direction. Extending substantially perpendicularly to the two directions in a direction perpendicular to the direction, and is flexible in any of the two directions over substantially the entire length thereof and has a front end at a free end. A pickup device in an optical information reading device, comprising four cantilever elongated flexible members supporting the objective lens.