JPH0140408B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a light condensing means support device for an optical information reproducing device, and in particular for optically reproducing information recorded in an optical information reproducing device. The present invention relates to an improvement in a condensing means support device for an optical information reproducing device that drives an objective lens condensing light.

Conventionally, as optical information reproducing devices, for example, video disc players and digital audio disc players are known. The disk used in this optical information reproducing apparatus generally has a track pitch of about 1 to 2 .mu.m and a track width of about 0.1 .mu.m. In order to optically reproduce information recorded on a disk formed at such a high density, the light spot from the light source must be focused to a diameter of about 1 to 2 .mu.m, similar to the track pitch. Therefore, the tracking error due to relative positional deviation between the track and the light spot must be maintained on the order of microns, and the focusing error due to positional deviation in the optical axis direction of the light spot from the light source must also be maintained on the order of microns. It must be. In order to control these tracking errors and focus errors, conventional optical information reproducing devices are provided with movable mirrors and voice coil actuators. That is, the movable mirror corrects the tracking error by deflecting the light from the light source in the radial direction on the disk. The voice coil actuator drives an objective lens that focuses light from a light source onto a track, and corrects focal errors by driving this objective lens in the optical axis direction.

However, in the conventional optical information reproducing device, the movable mirror and the voice coil actuator are separately provided in the optical path of the light from the light source, so there is a problem that the device cannot be miniaturized. Also,
Since conventional optical information reproducing devices control tracking errors by deflecting light from a light source using a movable mirror, it was necessary to take into account aberrations caused by the optical axis tilt of the objective lens.

Therefore, an object of the present invention is to be able to reduce the size with an inexpensive and simple configuration, to correct errors using only the objective lens without deflecting the light from the light source, and to eliminate the need to take into account aberrations caused by the optical axis tilt of the objective lens. It is an object of the present invention to provide a light condensing means support device for an optical information reproducing device.

To summarize, the present invention corrects tracking errors and focusing errors using a condensing means that condenses light from a light source onto a track.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a front view of a condensing means support device of an optical information reproducing apparatus according to an embodiment of the present invention.

FIG. 2 shows a cross-sectional view of this embodiment.

FIG. 3 shows an external view of the movable yoke 21 of this embodiment.

FIG. 4 shows the magnetic path of the magnet 26 in this embodiment.

Next, the configuration will be described with reference to FIGS. 1 to 4. The condensing means support device of the optical information reproducing device is composed of at least a light source (not shown), an objective lens 11 as an example of the condensing means, a control circuit (not shown), and a driving section 20 as an example of the driving means. Ru. As shown in FIGS. 1 and 2, the drive unit 20 is configured such that an objective lens 11 can move up and down in the optical axis direction A of light 12 from a light source, and a disk 13 which is an example of a recording medium.
The information track 131 is configured to be rotatable along the information track 131 in the radial direction B of the information track 131.

More specifically, the objective lens 11 is fixed at a certain position in the hollow cylindrical portion 211 of the movable yoke 21. As shown in FIG. 3, the movable yoke 21 is formed into a rectangular parallelepiped shape having a hollow cylindrical portion 211 in which the objective lens 11 can be accommodated. A focus control coil 22, which is an example of a first coil, is provided on the outer focusing surface of the movable yoke 21.
is wound so as to move the leaf spring 23, which is an example of a moving member, in the optical axis direction A. The leaf spring 23 has a hole 2 at one end thereof through which at least the light 12 from the light source passes.
31 (in the illustration, a hole having approximately the same diameter as the objective lens 11) is formed. The leaf spring 23 is attached to the movable yoke 21 such that the hole 231 faces the hollow cylindrical portion 211.
to clamp. The other end of the leaf spring 23 is fixed by a spring support stand 24, which is an example of a fixed part. Spring support stand 24
has a movable yoke 21 on both sides to which a plate spring 23 is fixed.
information track 13 in the radial direction B of the disk 13
The pivot bearing 241 rotates along the
is formed. A pivot support portion 25 for supporting the spring support base 24 is provided on the frame 30 facing the pivot bearing 241. This frame 30 is the drive unit 2
0, and a hole through which at least light 12 from the light source passes is formed. On the outer periphery of the movable yoke 21, a magnet 26, which is an example of a magnetic flux generating means, and a fixed yoke 27 are arranged so as to surround the movable yoke 21.
will be provided. That is, the two magnets 26 having the same shape are arranged in parallel on both sides of the outer peripheral surface of the movable yoke 21 at the same position with a certain gap provided in the radial direction B of the disk 13. Further, the fixed yoke 27 is formed to be longer in its longitudinal direction by twice the length of the short side of the magnet 26. The fixed yoke 27 formed in this way is connected to the magnet 26.
is located at the same position where the magnet 26 is placed.
In other words, in the radial direction B of the disk 13,
It is placed at a position with a certain gap in the direction perpendicular to the . A track tracking control coil 28, which is an example of a second coil, is wound around the outer circumference of the fixed yoke 27 in the longitudinal direction so as to rotate the movable yoke 21 along the information track 131 in the radial direction B of the disk 13. Ru.

The magnet 26 is provided so that its magnetic path is fixed yoke 27 - movable yoke 21 - fixed yoke 27 as shown in FIG. Further, the shape of the movable yoke 21 is not necessarily limited to a rectangular parallelepiped.

Next, the operation of this embodiment will be explained with reference to FIGS. 1 to 4. First, correction due to focus error will be described. In this case, a current corresponding to the focus error from a control circuit (not shown) flows through the focus control coil 22 in a direction to move the movable yoke 21 up and down in the optical axis direction A, as shown in FIG. Therefore, the leaf spring 23 receives a force in the optical axis direction A by an amount of current corresponding to the focus error, and is displaced about the spring support base 24 as a fulcrum. As a result, the objective lens 11 corrects the positional deviation of the light 12 from the light source in the optical axis direction.

Next, correction due to tracking error will be described. In this case, a current corresponding to the tracking error from the control circuit flows through the track tracking control coil 28 in a direction that causes the movable yoke 21 to rotate along the information track 131 in the radial direction B of the disk 13. Therefore, the leaf spring 23 is rotated by receiving a force in the radial direction B by an amount of current corresponding to the tracking error. As a result, the objective lens 11 corrects the relative positional deviation between the information track 131 and the light spot of the light 12 from the light source.

FIG. 5 shows a sectional view of a condensing means support device of an optical information reproducing apparatus according to a preferred embodiment of the present invention.

FIG. 6 shows a front view of the preferred embodiment.

In configuration, this embodiment is similar to FIGS. 1 and 2.
The difference from the figure is that the spring support base 24 is formed in a concave shape, and an elastic body 50 is placed between the concave surface 242 and the frame 30.
This means that the . As shown in FIG. 6, when the entire leaf spring 23 rotates in the radial direction B, the elastic body 50 has a center of rotational displacement at the pivot support portion 25.
on the central axis O-O'.

By attaching the elastic body 50 in this manner, the rotation center position of the leaf spring 23 in the radial direction B can be set, and there is an advantage that the rotation angle can be limited.

In addition, although the above-mentioned embodiment has been described using a magnet as the magnetic flux generating means, the present invention is not limited to this, and other magnetic flux generating means may be used. Further, in the above embodiment, the long side of the fixed yoke is twice as long as the short side of the magnet. However, the long side of the magnet is not limited to this. It is also possible to use one that is twice as long as the side.

As described above, according to the present invention, the condensing means for condensing light from the light source onto the information track is moved up and down in the optical axis direction and rotated along the information track in the radial direction of the recording medium. By the way,
Without deflecting the light from the light source, it is possible to reduce the size with an inexpensive and simple configuration, and by driving only the condensing means, tracking errors and focusing errors can be corrected. Therefore, the driving force for error correction may also be small. Furthermore, since the optical axis of the condensing means is supported in a direction substantially perpendicular to the disk surface, there is an effect that there is no need to take into account aberrations caused by optical axis tilt.

[Brief explanation of drawings]

FIG. 1 shows a front view of a condensing means support device of an optical information reproducing apparatus according to an embodiment of the present invention. FIG. 2 shows a cross-sectional view of this embodiment. FIG. 3 shows an external view of the movable yoke of this embodiment. FIG. 4 shows a magnetic path distribution diagram of the magnet of this embodiment. FIG. 5 shows a sectional view of a condensing means support device of an optical information reproducing apparatus according to a preferred embodiment of the present invention. 6th
The figure shows a front view of the preferred embodiment. In the figure, 11 is an objective lens, 13 is a disk, 131 is an information track, 21 is a movable yoke,
22 is a focus control coil, 23 is a leaf spring, 24 is a spring support, 25 is a pivot support, 26 is a magnet, 27 is a fixed yoke, 28 is a track tracking control coil, and 50 is an elastic body.

Claims (1)

[Scope of Claims] 1. A light condensing means for forming the light spot by detecting a track deviation of the light spot with respect to the information track of the disk on which information is recorded and a focus deviation of the light spot with respect to the information recording surface of the disk. The position of the information track is controlled according to the detected amounts of the track deviation and defocus, and the information is optically read out from the information track by the light spot irradiated from the controlled condensing means, wherein the information is read out optically from the information track. a rotating mechanism that is rotatably supported about an axis substantially orthogonal to the axis; an elastic member that is provided on the rotating portion of the rotating mechanism and that is movable up and down in the axial direction with one end as a fulcrum; The member is supported at the other end of the member so that its optical axis is substantially parallel to the axis, and focuses a light beam emitted from an optical system including a light source provided on a fixed portion of the rotating mechanism onto the disk surface. a condensing means for emitting light, a means for controlling the track deviation by rotating the condensing means about the axis, and controlling the defocus by moving the condensing means up and down in the axial direction; A condensing means support device for an optical information reproducing device, comprising: 2. The condensing means support device for an optical information reproducing device according to claim 1, wherein the elastic member is comprised of a pair of elastic pieces disposed above and below in the axial direction.