JPS60254425A - Objective lens driving device used for optical information reader - Google Patents

Abstract

PURPOSE:To completely eliminate the lead wire, etc., projected from a movable section and to simplify the constitution, by moving an objective lens supporting member and objective lens in the directions of focus and track around a guide shaft by utilizing the interaction between a magnet fixed to the objective lens and a coil fixed to the main body side. CONSTITUTION:An objective lens supporting member 22 is put on a guide shaft 23, with the inner peripheral section of a guide cylinder section 22a united with the member 22 in one body being contacted with the guide shaft 23 under a sliding-free and rotation-free condition and the top section of the guide shaft 23 being projected from the member 22. When electricity is supplied to a coil 26 for driving in the focussing direction, magnets 24a and 24b which are movable sections move in the focussing direction F together with the objective lens supporting member 22 as a result of the magnetic interaction between the magnets 24a and 24b and drive an objective lens 21. Moreover, when a track current IT is made to flow to another coil 27 for driving in the track direction, the left side magnet 24a moves to the back of the paper and the right side magnet 24b moves to the front side of the paper. Therefore, the objective lens supporting member 22 rotates clockwise around the guide shaft 23.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Purpose of the Invention 1. The present invention is used in an apparatus for optically reading information digitally recorded on a disc-shaped recording medium. The present invention relates to an objective lens driving device.

11. In order to record various input signals using a recording medium such as a compact disk (CD disk), it is necessary to convert them into bits, that is, digital signals of "0" and "1", write them, and read them. In some cases, an optical pickup equipped with an objective lens is moved along the disk surface, and a laser beam is used for detection by optical means.

The reading device described in ``2'' requires an optical system that uses an objective lens to focus light onto a spot of the same size as a small hole (pit) recorded on the disk. In addition to using a laser beam, focusing control and I-racking control between the objective lens and the disk must be performed accurately. Therefore, the objective lens installed in the optical pickup must be of a two-dimensional drive type that can be moved and adjusted in both the focus direction, that is, the direction perpendicular to the disk surface, and the track direction, that is, the radial direction of the disk surface. is necessary.

As a conventional two-dimensional drive type objective lens drive device, there is a movable coil type drive device that uses a voice coil for driving in the focus direction and a flat coil for driving in the track direction. It is widely used.

For example, in the case of the conventional example shown in FIG. 9, the objective lens 1 is fixed to the objective lens support member 2, and the objective lens support member 2 is 1
They are fitted together so that they can move in the rack direction T and focus direction F. As shown in FIG. 10, a plurality of flat coils 4, 4 for driving in the track direction are arranged on the outer peripheral surface of the objective lens support member 2, and a coil 5 for driving in the focus direction is wound on the outside thereof. The magnet 6 is arranged in a magnetic gap 8 formed by the magnet 6 and the yokes 7a and 7b shown in FIG.

FIG. 12 is a plan view showing the arrangement of the above-described main components.

In the above configuration, when a current is applied to the focus direction drive coil 5, the objective lens support member 2 can be moved in the focus direction F based on magnetic interaction.

On the other hand, the track direction drive coil 4 is configured using four coils in the illustrated example, and current flows in the same direction within the magnetic gap 8. The objective lens support member 2 can be moved in the track direction T. Reference numeral 10 shown in FIG. The other end of the lead wire 11 is soldered to the fixed substrate 10 and led out to the outside, so that power is supplied when each coil is energized.

However, in such a conventional objective lens driving device, the shape of each coil is complicated, and the number of man-hours during manufacturing increases. That is, in the illustrated example, four track direction drive coils 4 are required, and each coil must be electrically connected, making the assembly operation cumbersome. In addition, since a large number of current-carrying lead wires P are drawn out from each coil l\, care must be taken to dispose of these lead wires at all times, and there are other drawbacks such as the risk of adversely affecting the vibration characteristics of the drive unit. have.

The present invention eliminates the various drawbacks that occur due to the structure of the objective lens drive device used in the conventional optical information reading device as described above, simplifies the structure, reduces the manufacturing process, and eliminates the need for external protrusions such as lead wires. The objective is to provide an objective lens driving device that is easy to handle and has good vibration characteristics by eliminating the parts.

(2) Structure of the Invention In order to achieve the above object, the present invention provides a guide shaft that passes through the support member to which the objective lens is fixed, and the objective lens is guided along this guide shaft. At least two magnets are formed so as to move in the focus direction of the disc-shaped recording medium and also to move in the track direction of the disc-shaped recording medium, and are fixed to opposing parts of the objective lens support member. Optical information characterized in that a bobbin is disposed, and a coil for driving the objective lens in the focus direction and a coil for driving the l-rack direction intersecting the coil for driving the objective lens in the focus direction are wound around the bobbin. The main focus is to obtain an objective lens drive device for use in a reading device.

"lost" one sex Embodiments of the present invention will be described in detail below based on the drawings.

FIG. 1 is a perspective view showing the entire first embodiment of the present invention. In the figure, reference numeral 21 denotes an objective lens, which is fixed to an objective lens support member 22. As shown in FIG. This objective lens support member 22
The inner circumferential portion of the integrally formed guide tube portion 22a is slidably and rotatably fitted into a guide shaft 23 that protrudes through the objective lens support member 22. Therefore, the objective lens support member 22 is formed to slide in the focus direction F of a disc-shaped recording medium (not shown) and rotate in the track direction T.

1 m long magnets 24a and 24b are fixed to opposing parts of the objective lens support member 22, and are adapted to slide and rotate integrally with the objective lens support member 22. This pair of magnets 24a and 24b are arranged so that their opposing surfaces have the same polarity (S), and their outer sides are formed into a cylindrical shape. A pair of bobbins 25.degree. 25 is disposed close to each of the magnets 24a, 24b at opposing positions on the outside of the magnets 24a, 24b.
Focus direction drive coil 26.2 inside 5.25
6 is wound, and a track direction driving coil 2 is wound on the outside thereof.
7. Wrap 27. By forming the outsides of the magnets 24a and 24b into a cylindrical shape, the magnets 24a and 24b
, 24b rotates, the distance from the adjacent coil is always constant. A balance weight 28 is fixed to the lower side of the objective lens support member 22 so that the center of gravity of the co-moving portion of the objective lens support member 22 coincides with the guide shaft 23.

Further, as shown in FIGS. 2 and 3, a viscoelastic member 29 such as silicone rubber is inserted between a rod 30 protruding from the objective lens support member 22 and a rod 31 protruding from the main body 32 side. Even if the lens 32 is turned upside down, the movable part is prevented from falling from the guide shaft 23, and the objective lens 21 can be set at a substantially neutral position.

The bobbins 25, 25 are arranged to face each other on the outside of the magnets 24a, 24b, and the guide shaft 23
The bobbins 25 and 25 are fixed to the main body 32 so that the distances from the bobbins 25 and 25 are equal to each other.

The operation of the objective lens driving device according to the present invention described above is as follows. First, the focus direction drive coil 26
When energized, the movable parts of the magnets 24a and 24b move in the focus direction F together with the objective lens support member 22 due to magnetic interaction with the magnets 24a and 24b.
The objective lens 21 is driven. For example, when a focus current shown by .largecircle. in FIG. 5 is applied, the magnets 24a and 24b move in the direction of arrow F. When one track current is applied to the track direction driving coil 27, the left magnet 24a shown in FIG. 5 moves to the opposite side of the page, and the right magnet 24b moves to the front side of the page. Therefore, the objective lens support member 22 rotates to the right about the guide shaft 23. Note that the focus direction driving coil 26 shown in FIG.
The Q mark drawn on the cross section of the figure indicates the direction of current flowing perpendicular to the plane of the paper and toward the opposite side, and the Q mark drawn on the cross section of the figure indicates the direction of current flowing towards the front side and perpendicular to the plane of the paper. Magnet 24a, 2
The direction of movement of 4b is determined by the direction of the current.

As is clear from the above operation description, the magnet 24a.

Due to the current flowing through the coil adjacent to 24b, the magnet 2
4a, 24b are driven, but the magnets 24a, 2
4b and the coil located on the far side across the bobbin 25, the current flows in the opposite direction to the coil adjacent to the magnets 24a and 24b, and the driving direction is also opposite. However, by maintaining the thickness of the bobbin 25 at a predetermined value or more, the influence of the distant coil can be eliminated.

FIG. 6 shows a second embodiment of the present invention, the basic configuration of which is the same as the first embodiment shown in FIG. 1, and is designated by the same reference numerals. In the case of the second embodiment, bobbin 2
It is characterized in that coils 33 and 34 are wound around 5a so as to intersect at a predetermined angle. 7th
The figure is a side view showing the above-mentioned winding state, and FIG. 8 shows a matrix circuit used during driving.

In both the first and second embodiments, it is desirable to reduce the weight of the objective lens support member 22 and the magnets 24a and 24b, which are movable parts, and the magnets 24a and 24b are mainly made of lightweight plastic. It is better to use plastic magnets.

Further, the focus direction drive coil and the track direction drive coil may be wound so as to be perpendicular to each other, or may be wound at a predetermined angle to each other.

(G) By using the present invention described in detail, the following operational effects can be obtained. That is, the objective lens support member and the objective lens are brought into focus by the interaction between the magnet fixed to the objective lens and the coil fixed to the main body side, with the guide shaft 23 passing through the objective lens support member as the center of rotation. Since the movable member moves in both the direction and the track direction, there are no lead wires or the like protruding from the movable part, and the structure is simplified. Therefore, the number of manufacturing steps is reduced, making it easy to manufacture and reducing costs.7 As mentioned above, by eliminating the lead wires from the movable parts, it is easier to handle during use, and the vibration characteristics are reduced. It can bring about various effects such as improvement.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a first embodiment of the device of the present invention, FIG. 2 is a plan view of the same, FIG. 3 is a side view of the same, and FIG. 4 is an IV of FIG.
5 is an enlarged view showing the working part, FIG. 6 is a perspective view showing the second embodiment of the present invention, FIG. 7 is a side view of the main part of FIG. 6, and FIG. The figure is a schematic circuit diagram used when driving the second embodiment, and FIG. 9 is a perspective view showing an example of a conventional device.
FIG. 10 is a cutaway perspective view of the main part, FIG. 11 is a sectional view of the main part, and FIG. 12 is a plan view of the main part. 21... Objective lens, 22... Objective lens support member, 23... Guide shaft, 24a, 24b... Magnet, 25... Bobbin, 26... Focus direction drive coil, 27...・1
Coil for driving rack direction, 28... Balance weight, 29... Viscoelastic member, 32... Main body. , Fig. 1 - Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7 Fig. 8 Fig. 9 Fig. 11

Claims (1)

[Scope of Claims] (1) In an objective lens drive device installed in an optical information reading device that optically detects information recorded on a rotating disk-shaped recording medium, a support member to which the objective lens is fixed. A guide shaft passing through is provided, and the objective lens is formed to move along the guide shaft in the focus direction of the disc-shaped recording medium and rotate in the track direction of the disc-shaped recording medium, and the objective lens At least two bobbins are disposed close to magnets fixed to opposing portions of the support member, and a coil for driving the focus direction of the objective lens and a track intersecting the coil for driving the focus direction are arranged around the bobbins. An objective lens driving device used in an optical information reading device, characterized in that a directional driving coil is wound therein. (2) An objective lens drive device used in an optical information reading device according to claim 1, wherein the focus direction drive coil and the track direction drive coil are wound at a predetermined angle to each other. (3) An objective lens drive device for use in an optical information reading device according to claim 1, wherein the focus direction drive coil and the track direction drive coil are wound so as to be orthogonal to each other.