JPS58108039A - Optical system driver of optical information recording and reproducing device - Google Patents

Abstract

PURPOSE:To obtain a small-sized device by supporting an optical system movably in a vertical direction, and controlling driving current for the 1st and the 2nd coils on the basis of a prescribed error signal. CONSTITUTION:A couple of rectangular magnets 22 and 23 are arranged facing each other while an objective lens 21 constituting the optical system is interposed. The magnets 22 and 23 have platelike members 24 and 25 with high magnetic permeability on the opposite surfaces and are wound with the 1st and the 2nd coils 26a and 26b, and 27a and 27b independently so that they cross at right angles on the surfaces of the platelike members 24 and 25. The magnet 22 and 23 are magnetized as shown in a figure and are fixed to a rectangular annular frame 28 having high magnetic permeability to couple themselves mutually and magnetically. A frame 28 forms one magnetic closed loop as shown by arrows in the figure to reduce leakage of magnetic flux.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical system drive device in an optical information recording/reproducing device.

In an optical information recording/reproduction device, an information recording medium such as a video disk records the video signal by forming minute pits (indentations) corresponding to the video signal as a spiral track on its surface. It is something. When playing such a video disc, the disc is rotated at a predetermined number of revolutions while a spot light is irradiated onto the video track, and changes in the intensity of the reflected light or transmitted light are converted into electrical signals, which are then used as video signals. It is something to be regenerated.

In the reproduction of this video disc, since the irradiation light must always accurately track the recording track, it is necessary to control the irradiation light in the radial direction of the disc, that is, in the tracking direction (tracking servo). Position control (focus servo) of the optical system in a direction perpendicular to the recording surface, that is, in the focus direction, is also required to accurately converge the irradiated light onto the surface. For this purpose, an optical system driving device is used that drives an optical system for irradiating a spot light onto the recording surface of the disk in accordance with a tracking error signal and a focus error signal.

FIG. 1 is a sectional view showing a conventional example of such an optical system driving device, and FIG. 2 is a plan view thereof. In FIG. 1 and FIG. 2, 1 is an objective lens constituting an optical system;
2 is a ring-shaped magnet, 3.4 is a plate forming a magnetic circuit, 5 is a focusing voice coil, 6 is a bobbin around which the coil 5 is wound, 7 is a movable iron piece fixed to the objective lens 1, and 8 is a movable iron piece. 11.12 is a plate-shaped support spring that supports the objective lens 1 and the movable iron piece 7 movably in the tracking direction; 13.14 is the objective lens 1, the movable iron piece 7, and the voice Circular support springs 15° and 16 that support the movable part consisting of the coil 5, bobbin 6, and plate-shaped support springs 11 and 12 so as to be movable in the optical axis direction of the objective lens 1, that is, in the focus direction, form a magnetic circuit for driving in the tracking direction. It is a plate that does.

In the above configuration, the magnet 2 is magnetized in the thickness direction, and generates magnetic flux in the gap formed by the plates 3 and 4. In this state, when a current is applied to the coil 5, a force is generated in the optical axis direction of the objective lens 1, and the lens 1 is driven.

Therefore, in a disc player that performs optical recording or playback, the irradiated light is automatically focused on the disc by passing a current through the coil 5 based on the focus error signal detected by the above method. Objective lens 1
The position of the object can be controlled.

On the other hand, the magnets 9 and 10 are magnetized in the same longitudinal direction, and generate magnetic flux between the plate 15 and the iron piece 7 and between the iron piece 7 and the plate 16, respectively. In this state, by passing a current through the coil 8, a force in the left-right direction shown in FIG. 2 is generated in a portion of the coil 8 that is within the magnetic flux.

However, since the coil 8 is fixed, it is necessary to match the direction of the current flowing through the two coils 8, and the movable objective lens 1 and the iron piece 7 receive a reaction and are driven in the left-right direction in FIG. 2, that is, in the tracking direction. be done. Therefore, by applying current to the coil 8 based on a tracking error signal detected by some method, the position of the objective lens 1 can be controlled so that the spot light correctly follows the information track.

However, in the optical system driving device described above, independent magnetic circuits are used for the focus servo and the tracking servo, and the support of the objective lens 1 also has one degree of freedom in the focus direction and the tracking direction. Since an independent support means is used, the number of parts is large, the structure is complex, and the shape makes it difficult to downsize.

The present invention has been made in view of the above-mentioned points, and it is an object of the present invention to provide an optical system drive device for an optical information recording/reproducing device that has a simple structure, is easy to assemble, and is suitable for downsizing.

The optical system driving device according to the present invention has at least one pair of magnets disposed opposite to each other sandwiching the optical system in a direction perpendicular to the optical axis of the optical system, and magnets arranged perpendicularly to each other on opposing surfaces of the magnets. r and a second coil are wound around a magnet, and a magnetic member is provided integrally with the optical system so as to face the magnet, and the optical system is movably supported in the perpendicular direction, and based on a predetermined error signal. The drive currents of the first and second coils are controlled.

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

FIG. 3 is a plan view showing one embodiment of the present invention, and FIG. 4 is a sectional view. In the figure, reference numeral 21 denotes an objective lens constituting an optical system, and a pair of rectangular magnets 22 and 23 are arranged opposite to each other with the objective lens 1 in between. The magnets 22 and 23 are provided with plate members 24 and 25 having high magnetic permeability on their respective opposing surfaces. And magnet) 2
2 and 23, as shown in FIG.
first and second coils 26α, 26b and 27α, respectively, perpendicular to each other on the surface of 25;

276 are each wound independently. magnet 22
, 23 are magnetized with the polarity shown in FIG. 3, for example.
Further, they are fixed to a rectangular annular frame 28 having high magnetic permeability and are magnetically coupled to each other. The frame 28 forms a magnetic closed loop as shown by the arrow in FIG.
Reduces leakage magnetic flux.

Reference numeral 29 denotes a magnetic member made of a high magnetic permeability material, and the magnetic member 29 is provided integrally with the objective lens 21 so as to face the plate members 24 and 25 with a predetermined gap therebetween, and further includes a support member. It is supported elastically and two-dimensionally in parallel by a pair of elastic supports 29 and 30. The elastic supports 29 and 30 are magnets) 22
, 23 and the magnetic member 29, it is strong against forces in this direction, and it is easy to move in the optical axis direction of the objective lens 21 and in the left and right directions in FIG. 21 can be moved in parallel (see FIG. 4).

In the above embodiment, the magnets 22 and 23 have plate members 24 and 25 having high magnetic permeability on each opposing surface, but the plate members 24 and 25 may be omitted. It is possible.

The operating principle when the plate members 24 and 25 are omitted is explained in the sixth section.
This will be explained based on the diagram. now, magnet) 22, 23
Assuming that is magnetized as shown in FIG. If you apply a current to
The coil portions located in the air gaps between the magnet 22 and the magnetic member 29, and between the magnet 23 and the magnetic member 29 have a direction perpendicular to the magnetic flux and current (in the direction of the arrow).
The force of is generated. However, the coil is 26g.

Since 266 is fixed, the movable magnetic member 29 is driven in the direction of the arrow by the reaction. In addition, a coil 26 is placed on each opposing surface of the magnets 22 and 23.
g, the coil 27 wound perpendicularly to 266;
α.

By applying a current to 276 (see FIG. 5), the magnetic member 9 can be driven in a direction perpendicular to the plane of the paper based on the same principle as described above. Therefore, the objective lens 21 is attached to the magnetic member 9, and the direction perpendicular to the plane of the paper is made to correspond to the focusing direction, and the arrow entry direction is made to correspond to the tracking direction.1. Focus servo and tracking servo can be performed by appropriately controlling the drive currents of the first and second coils 26g, 266, 2'la, 276 based on the focus error signal and the tracking error signal.

Further, as shown in FIG. 7, when plate members 24 and 25 are provided, the magnetic flux generated by the magnet 22 passes through the plate member 24, which also has high magnetic permeability. The magnetic member 2
Similarly, the magnetic flux that has passed through the magnetic member 9 also concentrates on the plate member 25 and enters the magnet 23. Therefore, the magnetic flux density across the portion of each coil that faces the magnetic member 29 is greater than when the plate members 24 and 25 are omitted, so that the driving efficiency of the magnetic member 29 increases.

FIG. 9 is a plan view showing another embodiment of the present invention, and FIG. 9 is a sectional view. In this embodiment, the frame 28 is made into a U-shape, and the objective lens path is attached to an elastic support.
1 to 1! 'The structure is supported only on one side, and the other structure is exactly the same as in FIGS. 3 and 4. According to this configuration, when reproducing the innermost circumference of the disk, there is an advantage that a large spindle motor, a disk clamper, etc. can be used because there is ample space, and the degree of freedom in shape is also increased.

As described in detail above, according to the present invention, the number of parts is small, the structure is simple and easy to assemble, and the size can be reduced. In addition, because the movable part uses lead wires and has a dangerous structure, the movable part can be driven smoothly, and there is no fear of breakage of the lead wire, so assembly is easy. Furthermore, since it is based on the operating principle of a moving iron (MI) type linear motor, linearity is good.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing a conventional example, Fig. 2 is a plan view thereof, Fig. 3 is a plan view showing an embodiment of the present invention, Fig. 4 is a sectional view thereof, and Fig. 5 is a coil winding. FIGS. 6 and 7 are diagrams for explaining the principle of operation, FIG. 8 is a plan view showing another embodiment of the present invention, and FIG. 9 is a sectional view thereof. . Explanation of symbols of main parts 21...Objective lenses 22, 23...Magnets 24, 25...Plate members 26α, 26b
, 27α, 27b...Coil 28...Frame 29...Magnetic member 30...Elastic support Applicant Pioneer Co., Ltd. Agent Patent attorney Motohiko Fujimura Maku1 Figure 2riJ

Claims (4)

[Claims] (1) An optical system drive device that drives an optical system for irradiating a recording surface of a recording medium with a spot light, the optical system being arranged opposite to each other with the optical system in between in a direction perpendicular to the optical axis of the optical system. at least one pair of magnets, first and second coils wound around the magnets so as to be orthogonal to each other on opposing surfaces of the magnets, and integrated with the optical system so as to face the magnets. and a support member that supports the optical system movably in the perpendicular direction, and controls drive currents of the first and second coils based on a predetermined error signal. An optical system drive device in an optical information recording/reproducing device, characterized in that: (2) An optical system drive device in an optical information recording/reproducing apparatus according to claim 1, wherein the magnetic member is made of a material with high magnetic permeability. (3) The magnet is provided with a plate-like member having high magnetic permeability on its opposing surface.
An optical system drive device in the optical information recording/reproducing apparatus according to item 1 or 2. (4) The optical information recording and reproducing apparatus according to claim 1, 2, or 3, wherein the pair of magnets are coupled by a magnetic member to form a magnetic closed loop. System drive device.