JPH0462136B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a three-dimensional control drive device for an optical disc playback device.

Examples of this type of optical disc playback device include video disc players and digital audio disc players. In order to record information on or reproduce information from the disk in a non-contact manner, these optical disk devices are designed to prevent the reading light spot from being out of focus with respect to the information recording surface of the disk, orthogonally to the optical axis, and to approximately match the information track of the disk. Three deviations are detected: the track deviation of the reading light spot in the orthogonal direction, and the time axis deviation in the direction of the information track of the disk perpendicular to the optical axis.
The reading light spot is set to 3 depending on the detected amount of deviation.
It is necessary to perform tracking control in two almost orthogonal directions.

Conventionally, these controls were generally performed as follows. That is, a focus actuator receives an incident light beam, controls and drives an optical means for condensing the incident light beam and outputting the reading light spot in the direction of the optical axis of the light beam, and a focus actuator that controls and drives the optical means to condense the incident light beam and output it to a reading light spot; a first rotating mirror device provided in the middle and controlled and driven by tilting the light beam in a direction perpendicular to the information track of the disk;
3 with a second rotating mirror device that is controlled and driven by tilting the light beam in the direction of the information track of the disk;
It used two control and drive devices.

However, this conventional method requires three control drive devices, making it difficult to downsize.
Furthermore, since the first and second rotating mirror devices are provided midway through the optical path of the light beam, there is a drawback that adjustment of the optical system is complicated. Furthermore, since the light beam is controlled by tilting it, the objective lens used in the optical means needs to sufficiently guarantee aberrations, which has the disadvantage of making the objective lens expensive.

This invention has been made in view of the above-mentioned drawbacks, and includes an optical means having an objective lens and a lens holder, a fixed shaft, and an optical means rotatably and slidably attached to the shaft. A holder that holds the optical means in a translatable manner at a position where the optical axis is eccentric from the center of the shaft, a first control coil attached to the holder, and a second control coil attached to the holder. and a third control coil that is attached to the lens holder and has a symmetrical shape with respect to the rotation axis, and is provided opposite to at least a portion of the first control coil and the second control coil. and a second permanent magnet provided opposite at least a portion of the third control coil, and the shaft, the holder, the first control coil, and the first permanent magnet. A rotary drive device for rotating the optical means by a permanent magnet is moved in the optical axis direction of the light beam by the shaft, the holder, a second control coil, and a first permanent magnet. The third control coil and the second permanent magnet control the thrust drive device to control the optical means in the direction of rotation by the rotation drive device and in the direction of movement of the light beam in the optical axis direction by the thrust drive device. By configuring translation drive devices that perform translational operations in substantially orthogonal directions, it is possible to incorporate controls for focus shift, track shift, and time axis shift into an integrated device, making it possible to reduce the size of the device. The object of the present invention is to provide a new and easy three-dimensional control drive device for an optical disc playback device.

An embodiment of the present invention will be described below based on the drawings. 1 indicates an entrance hole 1b for the light beam a in the bottom part 1a.
and a housing having four sides 1c to 1f, 2
3 is a shaft fixed to the center of this housing, 3 is a bearing supported on this shaft via a Teflon resin coating with a low friction coefficient, and slides with a clearance of several μm to several tens of μm with respect to shaft 1. It is supported freely and rotatably.
Reference numeral 4 denotes a holder supported by the bearing 3 so as to be rotatable in the direction of the arrow A in the figure and slidably in the direction of the arrow B in the figure through the bearing 3;
The four side surfaces 1c to 1f have four side surfaces 4a to 4d facing each other through gaps, and the two opposing side surfaces 4
A and 4c are the sides of the arc.
5a and 5b are supports which are a pair of parallel plates made of an elastic body with one end fixed to the bottom of the holder;
It is supported so as to be movable in the direction of arrow C in the figure. Reference numeral 6 denotes a symmetrical lens holder fixed to the other end of this parallel plate, which is connected to the entrance hole 1b of the housing 1.
It has an entrance hole 6a at a position opposite to. Reference numeral 7 denotes an objective lens fixed to the entrance hole 6a of this lens holder, into which the light beam a that has passed through the entrance hole 1b of the housing 1 and the entrance hole 6a of the lens holder 6 is incident. It focuses the light to provide a reading light spot b,
Together with the lens holder 6, it constitutes an optical means. 8 are side surfaces 4a to 4d of the holder 4
Second control coils 9a to 9d for defocus control are wound around the outer periphery of the holder 4 on the side surfaces 4a to 9d.
The first control coils 10a and 10b for track deviation control are attached to the second control coil 8 at the outer circumferential corner 4d, and are attached to the inner surfaces of both opposing sides 1c and 1e of the housing 1, respectively. A pair of first permanent magnets are fixed so as to face each other with a gap between the arcuate side surfaces 4a and 4c of the holder 4, and are arranged so that the same polarity faces each other.
It faces at least a portion of the control coils 9a to 9d and the second control coil 8. Reference numeral 12 denotes a third control coil for time lag control, which is disposed at the center of the lens holder 6 and is wound in a cylindrical shape symmetrical about the rotation axis of the optical means. A pair of second permanent magnets are fixed to the upper ends of both opposing sides 1d and 1f of the casing 1 so as to face at least a portion of the third control coil 12 with a gap therebetween. are arranged so that they are facing each other. 14a and 14b have one end connected to the housing 1
It is an elastic body made of metal such as rubber material or spring stainless steel, whose other end is fixed to the bottom 1a of the holder 4, and the other end is fixed to the upper end of both opposing sides 4b, 4d of the holder 4. It creates a neutral point of motion in the direction.

Then, the shaft 2, holder 4, support body 5
a, 5b, the first control coils 9a to 9d, and the first permanent magnets 10a, 10b constitute a rotary drive device, and this rotary drive device controls the optical means consisting of the lens holder 6 and the objective lens 7. control the track deviation of the reading light spot b by rotating the
The shaft 2, the holder 4, the supports 5a, 5b,
Second control coil 8 and first permanent magnet 10
a and 10b constitute a thrust drive device, and the thrust drive device moves the optical means up and down in the direction of the optical axis of the light beam a to control the defocus of the reading light spot b. body 5
a, 5b, the third control coil 12, and the second permanent magnets 13a, 13b constitute a translational drive device, and this translational drive device translates the optical means in the left-right direction to move the reading light spot b. This is to control defocus. In other words, the optical means is held so as to be movable in three axes substantially orthogonal to each other as indicated by arrows A, B, and C in the figure by means of a rotational drive device, a thrust drive device, and a translation drive device. Note that when the optical means is rotated by the rotary drive device, since the holder 4 moves in a circular arc, the optical means also moves in a circular arc, and strictly speaking, the direction of movement by the thrust drive device and the direction of movement by the translation drive device are orthogonal. However, both the direction of movement by the thrust drive device and the direction of movement by the translation drive device
This is about 0.1 to 0.2 mm, and since the distance between the center axis of rotation, that is, the shaft 2, and the objective lens 7 of the optical means is several mm or more, this does not pose a problem.

In the three-dimensional control drive device for the optical disk device configured in this way, its operation is based on the light beam a.
When a track deviation of the reading light spot b in a direction perpendicular to the optical axis direction of the disc and perpendicular to the information track of the disk is detected, and a current corresponding to the detected amount flows through the first control coils 9a to 9d, this First control coils 9a to 9d and first permanent magnet 10
The holder 4 and the optical means are rotated in the direction of the arrow A in the drawing due to the relationship with the magnetic circuit constituted by a and 10b, and track deviation is controlled, and the focus deviation of the reading light spot b with respect to the information recording surface of the disk is prevented. When a current is detected and a current corresponding to the detected amount flows through the second control coil 8, the holder is 4 and the optical means are moved in the direction of arrow B in the figure to control the focus shift, and furthermore, the time axis shift of the information track on the disk is detected, and a current corresponding to the detected amount flows to the third control coil 12. , this third
control coil 12 and second permanent magnet 13a, 1
Due to the relationship with the magnetic circuit constituted by 3b, the optical means is moved in the direction of arrow C in the figure by the deflection of the supports 5a and 5b, thereby controlling the time axis shift.

In this way, the track deviation, focus deviation, and time axis deviation of the reading light spot b can be controlled by one control and drive device, resulting in a very small size and an extremely small number of component parts. . Moreover, since the control and drive device is separate from the optical system, the control and adjustment of the reading light spot b becomes easy, and the light beam a incident on the objective lens 7 of the optical means is not tilted.
This also makes it possible to reduce the cost of the objective lens 7.

Further, an optical means and a holder 4 which are movable parts are provided.
It is sufficient to provide only the first control coils 9a to 9d, the second control coil 8, and the third control coil 12, and the first permanent magnets 10a, 10b and the second permanent magnets 13a, Since 13b is provided in the housing 1, the weight of the movable part is significantly reduced, and the operating efficiency is significantly reduced.

Further, even if the optical means moves due to the control of the time axis shift by the third control coil 12 and the second permanent magnets 13a, 13b, the holder 5 only bends and the holder 5 does not move. The opposing positions of the first control coils 9a to 9d and the second control coil 8 and the first permanent magnets 10a and 10b do not change, and the third control coil 12 is rotated around the rotation axis of the optical means. Due to its symmetrical shape, even if the optical means is rotated by the rotary drive or raised or lowered by the thrust drive, the third control coil 12
The opposing positions of the second permanent magnets 13a and 13b do not change. Therefore, these control coils and permanent magnets are arranged so that they always face each other correctly even when the optical means moves, so that the arrows A,
There is no imbalance between the driving forces in the B and C directions, and stable operation can be obtained.

In the above embodiment, the rotational drive device controls the track deviation, and the translational drive device controls the time axis deviation.
Even if the rotation drive device controls the time axis shift and the translation drive device controls the track shift, the same effects as in the above embodiment can be obtained.

As described above, the present invention includes an optical means having an objective lens and a lens holder, a fixed shaft, and the optical means is rotatably and slidably attached to the shaft, and the optical axis of the optical means is attached to the shaft. a holder for translatably holding the optical means at a position eccentric from the center of the lens; a first control coil attached to the holder; a second control coil attached to the holder; and the lens holder. a third control coil mounted on the controller and having a symmetrical shape with respect to the rotation axis, and a first control coil provided opposite to at least a portion of the first control coil and the second control coil. a permanent magnet, and a second control coil provided opposite at least a portion of the third control coil.
a rotary drive device for rotating the optical means by the shaft, the holder, the first control coil, and the first permanent magnet; and a thrust drive device for moving the optical means in the optical axis direction of the light beam by the first permanent magnet, and by the third control coil and the second permanent magnet,
Since the optical disc is configured with a translation drive device that translates the optical means in a direction substantially perpendicular to the rotation direction of the rotation drive device and the direction of movement of the light beam in the optical axis direction of the thrust drive device, As a control device that can independently control track deviation, time axis deviation, and focus deviation in a playback device without affecting other devices, it can be made small, the number of component parts can be reduced, and the tracking control of the reading light spot is easy. This has the effect of

[Brief explanation of the drawing]

1 to 4 show one embodiment of the present invention, in which FIG. 1 is a plan view of a three-dimensional control drive device, and FIG.
The drawings are a cross-sectional view taken from FIG. 1, FIG. 3 is an enlarged partial cross-sectional view, and FIG. 4 is a partial perspective view. In the figure, 2 is a shaft, 4 is a holder, 5a,
5b is a support body, 6 is a lens holder, 7 is an objective lens, 8 is a second control coil, 9a to 9d are first
control coils, 10a and 10b are first permanent magnets, 12 is a third control coil, 13a and 13b
is the second permanent magnet.

Claims (1)

[Claims] 1. An optical means having an objective lens into which a light beam is incident, which condenses the incident light beam and emits a reading light spot, and a lens holder that holds the objective lens, a fixed shaft, and the shaft. a holder rotatably and slidably attached to the shaft, and holding the optical means in a translatable manner at a position where the optical axis of the optical means is eccentric from the center of the shaft; and a first control device attached to the holder. a coil, a second control coil attached to the holder, a third control coil attached to the lens holder and having a symmetrical shape with respect to the rotation axis, the first control coil and the above. A first permanent magnet provided to face at least a portion of the second control coil; and a second permanent magnet provided to face at least a portion of the third control coil. The optical means is rotated by the shaft, the holder, the first control coil, and the first permanent magnet to detect a track deviation of the reading light spot with respect to the information track of the disk on which information is recorded, or a track deviation of the disk. A rotary drive device that controls one of the time axis deviations of the information track is moved by the shaft, the holder, the second control coil, and the first permanent magnet in the direction of the optical axis of the light beam. , the thrust drive device for controlling the focal shift of the reading light spot with respect to the information recording surface of the disk is rotated by the third control coil and the second permanent magnet, and the optical means is rotated by the rotation drive device. The reading light spot is translated in a direction substantially perpendicular to the direction of movement of the light beam in the optical axis direction by the thrust drive device, and the track deviation of the reading light spot with respect to the information track of the disk or the time axis deviation of the information track of the disk is corrected. A three-dimensional control drive device for an optical disc playback device, each comprising a translation drive device controlling the other.