JPS58146035A - Information reproducing device - Google Patents

Abstract

PURPOSE:To execute positioning control with high accuracy with simple constitution, by driving an objective lens by a rectangular moving coil which is suspended by a wire. CONSTITUTION:A moving coil 12 is wound around a rectangular winding core 11. To the winding core 11, an objective lens 22 and small magnets 13, 14 are fitted. To the moving coil 12, a radial magnetic flux passes through from a magnet which is not shown in the figure, through a yoke 20. The winding core 11 is supported by wires 17-19. When the coil 12 is conducted the objective lens moves in the X direction, namely, in the focusing direction. When a coil 16 is conducted, said objective lens moves in the Y direction, namely, in the tracking direction.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical information reproducing apparatus that irradiates a disk surface with a laser beam, detects the reflected beam, and converts the reflected beam into an electrical signal.

The configuration of an optical information reproducing apparatus using a laser beam, such as a video disc player 17-, is shown in FIG. In this device, a laser beam emitted from a laser light source 1 passes through a collimator lens 2 to a beam splitter 3.
After passing through there, the light passes through a quarter-wave plate 4 and an objective lens 5, and then converges onto a disk 6.

This laser beam is modulated when reflected by the disk 6. Therefore, the information recorded on the γ iscro is captured in the reflected modulated light.

The reflected beam passes through the objective lens 5 and 1/4 wavelength plate 4 again, enters the beam splitter 3, and this time passes through the cylindrical lens 7 and reaches the light receiving element 8. The light receiving element 8 outputs an electric signal according to this reflected beam. Here, since the disk 6 is rotating at a constant speed, continuous information can be extracted from the light receiving element 8.

In order to extract information accurately with such a device, the distance between the objective lens 5 and the disk 6 must be maintained accurately at the focal length of the objective lens 5, and the information on the disk 6 must be kept precisely at the focal length of the objective lens 5. You need to focus on the track. Therefore, the objective lens 5 can be moved not only in the focal direction (X direction in FIG. 1) but also in the
- It is also necessary to move it in the direction perpendicular to the rack (Y direction in Figure 1). In the conventional device, the configuration for this movement is extremely complicated, and the device itself is expensive.

The present invention has been made in view of these points, and it is possible to control the focal position of an objective lens placed opposite to the disk surface.
The track tracking control is performed by a moving coil wound in a rectangular shape and suspended by a wire, and track tracking control is performed by applying force in the direction of the long side or short side of the rectangle to the winding core of the moving coil, so that the structure is simple. This realizes an information reproducing device that can perform highly accurate positioning control.

Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 2 is a perspective view showing essential parts of an embodiment of the present invention, and FIG. 3 is a cross-sectional view of AΔ' in FIG. In both figures, 11 is a winding core bent into a rectangular shape, and 12 is a moving coil wound around the winding core 11 in a rectangular shape. 13.14 is the winding core 11
The small magnets are attached to one side of the movable coil 12 so as to sandwich the movable coil 12, and are arranged in a positional relationship such that the magnetic poles are oriented in the Y direction and the magnetic pole directions are reversed. 15 is an electromagnet having magnetic poles 15a and 15b facing small magnets 13 and 14; 16 is an excitation coil for the electromagnet 15; and 17 to 19 are wires that support the winding core 11 so that it can be displaced in the X and Y directions. . Also, 20 is the first. A yoke 21 consisting of the second yokes 20a and 20b is a magnet to which the yokes 20a and 20b are fixed under L. The moving coil 12 is placed in the magnetic gap formed by the yokes 20a and 2Qb.

22 is an objective lens attached to one end of the winding core 11.

The operation of the device configured in this manner will be described next.

First, the driving operation in the X direction will be explained.

When an excitation current is applied to the movable coil 12, a force in the X direction acts on the movable coil 12 according to Fleming's left hand rule, the wires 17 to 19 are bent, and the movable coil 12 is displaced in the X direction. If the direction of the current flowing through the moving coil 12 is reversed,
The moving coil 12 is displaced in the opposite direction. Therefore, when a control signal (current) is applied to the movable coil 12 in accordance with the direction and amount of shift of the focal position, the objective lens 22 attached to the winding core 11 is also displaced together with the movable coil 12. , focusing can be performed.

Next, the driving operation in the Y direction will be explained.

When an excitation current is passed through the excitation coil 16, the electromagnets 15 act to cause the magnetic poles 15-a, 15b and the small magnets 13, 14 to perform repulsion or attraction depending on the polarity of the current flowing through the excitation coil 16. Therefore, if the electromagnet 15 is fixed, the winding core 11 can be displaced in the Y direction (coinciding with the long side or short side direction of the rectangle of the winding core 11). When the winding core 11 is displaced, the objective lens 2 attached to it
2 is also displaced in the same direction, tracking can be performed by applying a control signal (current) according to the direction and amount of deviation of the disk 6 from the track.

As described above, in this embodiment, by passing a current through the movable coil 12 and the excitation coil 16, the X of the objective lens 22,
Position control in the Y direction, in other words, focusing and tracking can be performed.

In the case of this information reproducing device, since the movable coil 12 is wound in a rectangular shape, the length of the movable coil 12 within the magnetic gap can be made sufficiently large, so that a large driving force can be obtained. Furthermore, since the winding core 11 is not displaced in the Z direction in FIG. 2, the gap distance in A can be made very small. Therefore, an extremely large driving force can be obtained compared to the conventional one, and positioning accuracy and frequency response during focusing are greatly improved. In addition, in this embodiment, the entire device is connected to the wire 1.
Since it is supported by 7 to 19, the configuration becomes simple.

In the above embodiment, the entire movable part is supported by three wires 17 to 19, and two small magnets 13 and 14 are provided above and below one surface of the winding core 11. It is not necessarily limited to this.

That is, the mounting position and number of the small magnets on the winding core 11,
The mounting position and number of the wires may be selected in any manner as long as the winding core 11 is not tilted during focusing or tracking. Therefore, the number of the wires does not need to be three, and it is not necessary that they all have the same diameter. Similarly, the above-mentioned small magnets may be provided on both sides of the winding core 11, or only one small magnet may be provided at a position where the winding core 11 is not tilted. Furthermore, the magnetic pole 1 of the electromagnet 15
5a (the same applies to 15b), if the shape is made wide in the X direction as shown in FIG. can be avoided, and interference between focusing and tracking operations can be almost completely eliminated.

As described above in detail, according to the present invention, it is possible to realize an information reproducing device with a simple configuration that can perform positioning control with island precision.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing an example of an information reproducing device, FIGS. 2 and 3 are configuration diagrams showing an embodiment of the present invention, and FIG. 4 is a configuration diagram showing a part of another embodiment of the present invention. It is a diagram. 1...Laser light source 2...Collimator lens 3...Beam splitter 4...1/4 wavelength plate 5.22...Objective lens 6...Disc 7...Cylindrical lens 8... Light receiving element 11... Winding core 12... Moving coil 13.14... Small magnet 15... Electromagnet
16... Excitation coil 17-19... Wire
20...Yoke 21...Magnet patent applicant Foster Electric Co., Ltd. Representative Patent attorney Fuji Ijima Figure 1 M2'') 9 Leather 3 Figure Leather 4 Figure 1

Claims (1)

[Claims] In an optical information reproducing device that irradiates a laser beam onto a disk surface, detects the reflected beam, and converts it into an electrical signal, the focus position of an objective lens placed opposite the disk surface is controlled using a wire wound in a rectangular shape. An information reproducing device characterized in that track tracking control is performed by a movable coil suspended by a movable coil, and track tracking control is performed by applying force in the direction of a rectangular long side or short side to a winding core of the movable coil.