JPH01192022A - Optical recording and reproducing device - Google Patents

Abstract

PURPOSE:To stabilize a displacement frequency characteristic in a focusing direction by providing a magnet which generates a magnetic field for driving symmetrically with respect to the center of gravity of a lens holder, and preventing a moment from being generated. CONSTITUTION:An objective lens 1 is supported by the lens holder 2, and forms a micro light spot on a recording medium. The holder 2 is mounted on an optical block 5 via a flat spring 3a. And the lens 1 performs parallel movement by a focusing coil 4 and a driving force generated by magnets 10a and 10b for the coil, and moves in the focusing direction F. Also, the lens 1 moves in a tracking direction T by the driving force generated by tracking coils 6a and 6b and magnets 8a and 8b for the coils via a block 5. At this time, the magnets 10a, 10b, and 8a, 8b are formed in columnar magnets, and whose longitudinal directions are arranged in parallel with a radius direction, and are arranged fixedly symmetrically with respect to the center of gravity of the holder by sandwiching the holder 2. In such a way, it is possible to prevent the moment from being generated around the center of gravity, and a stable displacement frequency characteristic in the focusing direction can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an optical recording and reproducing device for optically recording and reproducing information.

Conventional technology Conventionally, optical recording and reproducing devices are composed of optical elements such as semiconductor lasers, collimating lenses, and half mirrors.
Means for detecting a focus error signal on a disk-shaped recording medium such as a magneto-optical disk, means for detecting a tracking error signal on the disk-shaped recording medium, and information detection means for detecting information on the disk-shaped recording medium. An optical block comprising an objective lens for forming a minute light spot on the disc-shaped recording medium is connected to a focus direction 1 in a direction perpendicular to the recording medium surface of the disc-shaped recording medium and the recording medium surface. and a mechanism for driving in a radial tracking direction T parallel to the recording medium, and optically records and reproduces information on the disc-shaped recording medium.

A conventional optical recording/reproducing device of this type has a configuration as shown in FIG. FIG. 4 is a perspective view of a main part showing the configuration of a conventional optical recording/reproducing device, and FIG. 4(B) is a plan view of the same.

That is, the lens holder 2 holding the objective lens 1 is attached to a part of the optical block 6 via plate-shaped elastic members 31L and 3b. A focusing coil 4 for driving the objective lens 1 in the focusing direction y is wound around the lens holder 2, using an electrodynamic transducer in which the focusing coil 4 is placed in the surface magnetic field of the focusing magnet 1o.

Drive in the focus direction F is obtained by translational movement in the focus direction y via the elastic members 32L and 3b. The focusing magnet 1o is separated from the optical block 6- and fixed to the magnetic yoke 11.

As shown in FIGS. 4(M) and 4(B), the optical block 6 connects to the magnetic yoke via ball bearings 7 & ~ 7h (partially omitted in the figure) provided at the front, rear, upper and lower ends of the side surface of the optical block 6. It is movably attached to the magnetic yokes 91L and 9b, and is configured to be movable only in the tracking direction τ along the magnetic yokes 91L and 9b. Furthermore, the optical block 6 includes a tracking coil 6a,
6b is attached, and the tracking magnet sa,
Drive in the tracking direction T is obtained by an electrodynamic transducer in which tracking coils 61L and 6b are arranged in the gap of a magnetic circuit consisting of ab and magnetic yokes ga and gb.

In the optical recording/reproducing device having the above structure, by separating the magnetic circuit for driving the objective lens in the focus direction y from the optical block, the mass of the entire optical recording/reproducing device can be reduced and the access time can be reduced. We are trying to shorten the time.

Problems to be Solved by the Invention However, as shown in FIG.
Since it is installed only on one side, a moment force M is generated around the center of gravity by the driving force P during driving. Therefore, at a certain frequency, the lens holder 2 enters a vibration mode in which it rotates around the center of gravity G, as shown in FIG. 3(B), and the displacement frequency characteristic of the objective lens 1 in the focus direction changes. There were problems such as disturbances occurring.

SUMMARY OF THE INVENTION In view of the above problems, the present invention provides an optical recording and reproducing apparatus that can realize stable displacement frequency characteristics of an objective lens while shortening the access time.

Means for Solving the Problems In order to solve the above problems, the present invention provides a lens holder having an objective lens that forms a minute light spot on the edged medium surface of a disc-shaped recording medium, and a lens holder that includes an objective lens formed of an elastic body. a moving means for moving in a radial direction parallel to the surface of the recording medium, and a coil for the optical axis direction (focusing direction) for driving the objective lens in the optical axis direction perpendicular to the surface of the recording medium; One end of the elastic body is attached to the lens holder and the other end is attached to the moving means so that the objective lens moves in translation in the optical axis direction, and the two columnar magnets extend in the longitudinal direction. Insert the lens holder so that it is approximately parallel to the radial direction,
The lens holder is fixedly arranged symmetrically with respect to the center of gravity of the lens holder.

Operation The present invention drives the objective lens in the focus direction with the above configuration. Because the magnetic circuit for the lens holder is fixed and separated from the optical block, access time can be shortened, and at the same time, since the lens holder is driven symmetrically with respect to its center of gravity, no moment force is generated around the center of gravity, and the focus direction It is possible to obtain stable displacement frequency characteristics with respect to

Example Embodiments of the present invention will be described below based on the drawings.

FIG. 1(M) is a perspective view of essential parts showing the configuration of an optical recording/reproducing apparatus according to an embodiment of the present invention, and FIG. 1(B) is a plan view thereof. As shown in FIG. 1, a lens holder 2 holding an objective lens 1 is attached to a part of an optical block 6 via leaf springs 3a and 3b provided parallel to each other. A focusing coil 4 for driving the objective lens 1 in the focus direction y is wound around the lens holder 2.
Column-shaped focusing magnet 10! Drive in the focus direction y is obtained by an electrodynamic transducer in which a focusing coil 4 is placed in the surface magnetic field of L and 10b, and is translated through leaf springs 31L and 3b. The focusing magnets 1oIL and 1ob are each configured so that its longitudinal direction is substantially parallel to the tracking direction T, and so as to sandwich the lens holder 2 therebetween. The optical block 5 has an inclined surface 51L at the upper end of the side surface and the lower side surface of the optical block 5.
, the ball bearings installed in each of 5b? ! L
~7h (partially omitted in the figure) through magnetic yokes 9a, 9
b, so that it can run, and the magnetic yoke 91L
.

It is configured to be movable only in the tracking direction T along the longitudinal direction of 9b. Furthermore, the optical block 6 includes a tracking coil e&.

6b is attached to surround the magnetic yokes ea and eb by a predetermined length, and the tracking magnets sa and s
A tracking coil 6& is placed in the air gap of the magnetic circuit consisting of magnetic yokes ea and gb.

Drive in the tracking direction T is obtained by the electrodynamic transducer arranged with 6b.

In the optical recording/reproducing apparatus of this embodiment, the focusing magnets 1o&, 1ob and the magnetic yoke 11 are used to drive the objective lens 1 and the lens holder 2 in the focus direction y.
Since a and 11b are fixed separately from the optical block 6, the mass of the entire optical recording/reproducing device can be reduced, and the access time can be shortened. At the same time, focus magnet 10IL.

10b and magnetic yokes 11&, 11b are arranged symmetrically with respect to the center of gravity of the lens holder 2, and no moment force is generated at the center of gravity when driven in the focus direction y, resulting in a stable displacement frequency in the focus direction. characteristics can be realized.

Next, another embodiment of the present invention is shown in FIG. 2. As shown in this embodiment, the optical block 6 is separated and fixed, and the light beam 14 emitted from the optical block 6 is attached to the transport body 12. Needless to say, if the light is configured to be incident on the objective lens 1 through the reflective mirror 13, the access time can be further shortened while maintaining stable displacement frequency characteristics in the focus direction y.

The optical block 6 is composed of optical elements such as a semiconductor laser, a collimating lens, and a half mirror. The configuration generally includes means for detecting an error signal and information detecting means for detecting information on the disc-shaped recording medium.

Effects of the Invention As described above, according to the present invention, the lens holder that holds the objective lens is connected to the moving means via the elastic body, so that the lens holder can move in the radial direction and optical axis direction of the recording medium. At the same time, two columnar magnets that apply a surface magnetic field to the optical axis direction coil are arranged so that the longitudinal direction of the columnar magnets is substantially parallel to the radial direction, and 1. By placing the lens holder in between, the magnetic circuit for driving the objective lens in the optical axis direction is fixed and separated from the optical block, reducing access time. Since the lenses are arranged symmetrically with respect to the center of gravity of the lens holder, no moment force is generated at the center of gravity, and stable displacement frequency characteristics in the optical axis direction can be obtained.

[Brief explanation of the drawing]

FIG. 1(M) is a perspective view of essential parts showing the configuration of an optical recording/reproducing device according to an embodiment of the present invention, FIG. 1(B) is a plan view of the same, and FIG. 2 is another embodiment of the present invention. FIGS. 3(B) and 3(B) are perspective views showing the configuration of the conventional optical recording and reproducing apparatus, and FIG. ) is a perspective view of a main part showing the configuration of a conventional optical recording/reproducing device, and FIG. 4(B) is a plan view thereof. 1... Objective lens, 2... Lens holder, 31L. 3b...Plate blade, 4...Focusing coil, 6...Optical block, csa, eb.
...Tracking coil, 71L, 7h...
...ball bearing, sa, sb...magnet, 9&, 9b...magnetic yoke, 10.10&,
10b...Focusing magnet, 11.111L
, 11b...magnetic yoke, 12...transfer body, 13...reflection mirror, 14...
Light beam, F... focus direction, T...
...Tracking direction. Name of agent: Patent attorney Toshio Nakao and one other person
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Claims (1)

[Claims] a lens holder having an objective lens that forms a minute light spot on the recording medium surface of a disc-shaped recording medium; a moving means that moves the objective lens in a radial direction parallel to the recording medium surface via an elastic body; and two columnar magnets that apply a surface magnetic field to an optical axis direction coil for driving the objective lens in the optical axis direction perpendicular to the recording medium surface, and the elastic body is arranged such that the objective lens is translated in the optical axis direction. One end of the columnar magnet is attached to the lens holder so as to move, and the other end is attached to the moving means, and the two columnar magnets are arranged such that their longitudinal directions are substantially parallel to the radial direction.
An optical recording/reproducing device, characterized in that the lens holder is inserted between the lens holders and the optical recording/reproducing device is fixedly arranged symmetrically with respect to the center of gravity of the lens holder.