JPS6126945A - Objective lens driver for optical information recording and reproducing device - Google Patents

Abstract

PURPOSE:To facilitate the winding of two coils and to attain the simple and assured control of the distance between both coils and two magnets, by using an objective lens holder that can move in both focusing and tracking directions as well as said two coils and two magnets. CONSTITUTION:When two track coils 105 are energized, coincidence is obtained between the directions where both coils 105 receive the force since two magnets 107 are set so that they have the same polarity at the side of an objective lens 1. Thus an objective lens holder 101 is driven toward the track direction T. When a focus coil 106 is energized, coincidence is obtained between the directions of the force received from magnets 107. Thus the holder 101 is driven in the focusing direction. The coil 105 is wound around a bobbin 104 and fixed to the holder 101. Thus no disconnection is caused since the coil 106 is wound orthogonally round the outer circumference of the holder 101. Furthermore the gap distance between the magnet and the coil can be controlled simply and accurately. This can decrease the number of manufacturing processes and improve the productivity of the titled objective lens driver.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an objective lens driving device used in an optical information recording device that writes information on an optical disk or an optical information reproducing device that reads information recorded on an optical disk.

Prior Art and Intervals An optical information recording device writes information by irradiating an optical disk with a laser beam focused by an objective lens, and an optical information reproducing device writes information by irradiating an optical disk with a laser beam focused by an objective lens. Although this device is different from the conventional one, it irradiates an optical disk with a laser beam focused by an objective lens and reads information recorded on the disk from the reflected light. The objective lens used in these optical information recording devices or reproducing devices can move in the focus direction, that is, the optical axis direction, and in the track direction, that is, the radial direction of the disk, in order to accurately write or read information. Therefore, the objective lens driving device must be of a two-dimensional type capable of focusing control and tracking control.

An example of a conventional two-dimensional drive type objective lens drive device will be described below with reference to the drawings.

3 to 5 show a conventional example, where FIG. 3 is a side sectional view, FIG. 4 is a plan view, and FIG. 5 is a perspective view showing the fixed state of the focusing coil and the tracking coil. be.

The objective lens 1 is fitted into and fixed to an objective lens support frame 2, and the objective lens support frame 2 is fixed to an intermediate member 4 to which a balance weight 3 is fixed. A plate spring 5 is attached to the intermediate member 4.
The plate spring 5 is fixed to the main body 8 integrally with the plate spring 7 via the relay member 6. A focusing coil 9 is wound around the outer periphery of the objective lens support frame 2, and tracking coils 10 are divided into four groups and arranged at the corners of the objective lens support frame 2. . The track coil 10 has gaps lla and ll in two magnetic circuits facing each other with the objective lens 1 in between.
The track coil 10 located in the gap lla and the track coil 10 located in the gap llb are wired so that current flows in the same direction within the same gap. Reverse 4
It is wired so that current can flow through it. The two magnetic circuits each include a U-shaped yoke 12 and a magnet 13, and are magnetized so that the objective lens 1 side has the same polarity (in FIGS. 3 and 4, the objective lens 1 side is N
pole) is fixed to the main body 8.

In the above configuration, when a current is passed through the focusing coil 9, the directions of the current across the gaps lla and llb are reversed, respectively, except for the gap 11a.

Since the directions of the magnetic flux lines generated in 11b are both toward the objective lens 1 side, the focusing coil 9 receives a force in the focusing direction F, and the objective lens 1 moves in the focusing direction F.

Furthermore, when a current is applied to the track coil 10, the current flows in the same direction within the same gap, so the track coil 10 receives a force in the track direction T, and the objective lens 1 moves in the track direction T. do.

However, in the conventional example, it is necessary to firmly fix the focusing coil 9 and the tracking coil 10 to each other as shown in FIG.
°Bending is required, and the coil is prone to breakage, resulting in poor productivity. In addition, while the focusing coil 9 and the tracking coil 10 are fixed, they must be placed within the gaps lla and llb so as not to contact the magnet 13, and there are restrictions on the number of turns of the coil and the gap distance. There was a problem in that precision was also required.

Purpose The present invention has been made in view of the above points, and it is possible to easily wind a focusing coil and a tracking coil, and to easily and reliably adjust the gap distance to the magnet. It is an object of the present invention to provide an objective lens driving device for an optical information recording or reproducing device that is small and has high productivity.

Configuration of example The present invention will be described in detail below based on the drawings.

FIG. 1 is a perspective view of one embodiment of the present invention, and FIG. 2 is a partially sectional side view of FIG. 1.

The objective lens 1 is fitted and fixed in an objective lens holder 101, and the objective lens holder 101 has eight elastic members 102.
It is installed in the main body 103 so as to be movable in the focus direction F and the track direction T via. Further, a track coil 105 is wound around the bobbin 104.
The two bobbins 104 are fixed to the objective lens holder 101 symmetrically with respect to the objective lens l with the track coil 105 wound thereon. Further, a focusing coil 106 is wound around the outer peripheral surface of the objective lens holder 101 and a bobbin 104 fixed to the objective lens holder 101 so as to be substantially orthogonal to the tracking coil 105. Further, on the outside of the focusing coil 106, there are magnets 107 facing each of the two bobbins 104.
A yoke 108 to which is fixed is disposed, and the yoke 108
One end is fixed to the main body 103. The two magnets 107 are magnetized so that the objective lens 1 side has the same polarity, and the two track coils 105
A focusing coil 10 is wound so that currents in opposite directions flow through the objective lens 1 between the opposing surfaces of the focusing coil 10.
The objective lens 1 is also sandwiched between the surfaces of the magnets 6 facing the two magnets 107, so that currents in opposite directions flow therebetween. Furthermore, the gap distances between the magnet 107 and the coils 105 and 106 are set to be approximately equal on both the left and right sides.

The operation of the objective lens driving device according to the present invention configured as described above will be explained.

First, in operation, when the track coil 105 is energized, the two magnets 107 have the same polarity on the objective lens side (N in the figure).
pole), and the track coil 1
Since current flows in opposite directions across the objective lens 105, the two tracking coils 105 receive forces in the same direction, and are driven by a predetermined amount in the tracking direction 'r.

Furthermore, even when the focusing coil 106 is energized, currents in opposite directions flow through the focusing coil 106 in the plane facing the two magnets 107, so that the focusing coil 106 receives a force from the two magnets 107. The directions coincide with each other and are driven in the focus direction F by a predetermined amount.

Note that the ■ symbol drawn on the cross section of the focusing coil 106 shown in FIG. 2 indicates the direction of the current flowing perpendicular to the page and toward the opposite side, and the O symbol indicates the direction of the current flowing perpendicular to the page and toward the front. ing.

As is clear from the above operation description, the objective lens 1 is equipped with a tracking coil 105 or a focusing coil 106.
Coil 105 or 106 according to the direction of current flowing in
is driven by receiving force from the magnet 107. In order to drive the objective lens 1 smoothly, each of the tracking coil 105 and the focusing coil 106 must be wound so that currents flow in opposite directions on the surfaces facing the two magnets 107. As in this embodiment, after winding the tracking coil 105 around the bobbin 104 and fixing it to the objective lens holder 101, the focusing coil 106 is wrapped around the outer peripheral surface of the objective lens holder 101 and the bobbin 104. 105
If the coils 105 and 106 are wound in a direction substantially perpendicular to the magnet 107 and the track coil 105, the coils 105 and 106 can be easily wound with little risk of wire breakage during manufacturing.
．． The gap distance to the focusing coil 106 can also be easily adjusted.

- As described above, according to the present invention, the coil can be easily wound with almost no risk of wire breakage, and the gap distance to the magnet can also be easily and reliably adjusted. Therefore, not only can manufacturing steps be reduced and productivity greatly improved, but also a compact and highly accurate objective lens driving device can be achieved.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of an embodiment according to the present invention, Fig. 2 is a partially sectional side view of the same, Fig. 3 is a side sectional view of a conventional example, Fig. 4 is a plan view of the same, and Fig. 5 is a conventional example. FIG. 2 is a perspective view showing a fixed state of a focusing coil and a tracking coil.

Claims (1)

[Claims] An objective lens holder is installed to be movable in a focusing direction and a tracking direction with respect to the main body, and an objective lens is fitted and fixed thereto, and the objective lens holder is fixed to both ends of the objective lens holder with the objective lens in between, and a track coil is wound around the objective lens holder. two bobbins, a focusing coil wound in a direction substantially perpendicular to the tracking coil over the outer circumferential surface of the bobbin and the objective lens holder, which are fixed to each other, and a focusing coil that is spaced at substantially equal distances from each of the bobbins. An objective lens driving device for an optical information recording/reproducing device, comprising two magnets facing each other and fixed to the main body via a yoke.