JPS63122028A - Lens actuator - Google Patents

Abstract

PURPOSE:To control two condensor lenses by a lens actuator with simple constitution by using a couple of focus drive sections and one set of tracking drive section so as to operate the two condensor lenses. CONSTITUTION:The focus control collating optimizingly the 1st and 2nd beams 71, 73 to a face of a recording medium 4 is conducted by the 1st 2nd focus actuators 81, 82 provided to a moving section 1 and the servo control mechanism comprising an external control circuit and position detectors (not shown) in 1st and 2nd focusing directions (a) corresponding respectively to the 1st and 2nd beams 71, 73 provided in the optical system 7. The 1st and 2nd actuators 81, 82 are arranged to drive the mechanism plated at a position deviated in the direction of the 1st and 2nd condensor lenses 11, 12 with respect to the gravity center of the moving section 1 and produces a torque in a direction to drive the moving section 1 corresponding to the difference of the force exerted by both the actuators 81, 82. Then the focus control is applied by the servo control mechanism so that the focus face of the condensor lenses 11, 12 is coincident with the face of the recording medium 4.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a lens actuator for an optical head that records information on a recording medium using optical means, or reproduces or erases already recorded information. In particular, the present invention relates to a lens actuator that moves a condenser lens in a focusing direction perpendicular to the surface of a recording medium and in a tracking direction parallel to the surface of a recording medium.

[Conventional technology]

An optical head that uses laser light as a light source and modulates this laser light with pulsed signals from an external information source to record binary information on the surface of a recording medium, or to reproduce or erase information that has already been recorded. In order to accurately record, reproduce, or erase information, a lens actuator is used to adjust the focus direction so that the recording medium surface is always at the focal point of the condenser lens. The axial position is controlled, and the laser beam is focused so that the light spot on the surface of the recording medium is accurately positioned with respect to the guide groove formed in advance on the recording medium. Tracking position control is performed by driving the optical lens in a tracking direction perpendicular to the guide groove. .

By the way, conventionally, in this type of optical head, the optical head has only one condenser lens. That is, conventionally, one optical head has only one condensing lens, and therefore, there is no single light spot for writing, reading, or erasing generated on the surface of the recording medium by this condensing lens. For example, in a magneto-optical disk drive, the only way to rewrite the recorded information is to erase the recorded information, wait for the disk to rotate to its original position, and then write new information. It was impossible to do.

Therefore, as a countermeasure to this problem, the present applicant has proposed a magneto-optical head having two condensing lenses arranged in the direction along the recording track on the surface of the recording medium. No., patent application 1986-2596
According to this, when rewriting information, the light spot from one of the condensing lenses is used for erasing, and the light spot from the other condensing lens is used for writing, and these are used for erasing and erasing. Since new information can be written in parallel, there is no need to wait for the disk to rotate to its original position as described above, and information can be rewritten faster than before. It has become possible.

[Problem that the invention seeks to solve]

However, if you try to perform the focus control and tracking position control as described above in such a magneto-optical head having two condensing lenses, and configure this using a lens actuator similar to the conventional one, in that case, teeth,
Since two sets of lens actuators are used in combination, a problem arises in that the head configuration becomes complicated, and furthermore, the two condensing lenses cannot be placed very close to each other. In a magneto-optical disk device that simultaneously generates separate optical spots for erasing and writing, the bias magnetic field applied at the position of the preceding optical spot for erasing and the optical spot for following writing on the recording trunk is Since it is necessary to reverse the direction, from this point of view it is not possible to bring the light spots very close together, but on the other hand, from the viewpoint of further reducing the wasted time from erasing to writing in such a two-light spot method, On the other hand, it is better to bring the two light spots as close together as possible. Therefore, when considering the device configuration, the distance between the two light spots should be a distance that is neither too close nor too far apart, for example, several n.
The level is considered appropriate.

However, this level of distance between the light spots is too close for a method in which two laser beams are incident on one condenser lens with their optical axes shifted, and it is difficult to use a method that uses two sets of lens actuators in combination as described above. However, this could not be easily achieved because it would be too far away.

It is an object of the present invention to further improve the above-mentioned problems and to provide a lens actuator that has a simple configuration and is capable of accurately forming two light spots on a recording medium with an interval of about several nanometers. be.

[Means for solving problems]

The present invention provides a lens actuator that moves a condensing lens that condenses light from a light source onto a recording medium in a focusing direction perpendicular to the surface of the recording medium and in a tracking direction parallel to the surface of the recording medium. a lens support mechanism that movably supports the movable part in the focusing direction and also movably in a rotational direction about the tracking direction; and drives two different parts of the movable part. It is characterized by having a first and a second focus driving section.

[Effect]

The movable part is centered on the focusing direction and the tracking direction so that the focal planes of the two condensing lenses mounted on the same movable part are aligned correctly on the surface of the recording medium according to the waviness of the surface of the recording medium. Erasing is achieved by moving a combination of movements in the rotational direction to form two sufficiently narrowed light spots, performing an erasing operation with the leading light spot, and recording with the following light spot. The operation and recording operations proceed almost in parallel with only a slight delay, making it possible to rewrite information at high speed. In addition, the above-mentioned operations in the focusing direction and rotational direction are performed using two different movable parts.
This is done in accordance with the average value and difference between the forces generated by the first and second focus drive sections that drive the focus drive section, but since the waviness of the recording medium surface is very slight and its frequency is low, Most of the force generated by the focus drive section is used for operation in the focusing direction. Therefore, the first and second focus drive sections need only be able to generate approximately the same driving force as a single conventional focus drive section, and can be constructed with almost the same size, and the tracking drive section Only one set of lens actuators is required, and the configuration of the lens actuator is much simpler than using two sets of lens actuators each driving one condensing lens.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a conceptual diagram showing an embodiment of the present invention.

As shown in FIG. 1, the lens actuator includes two condensing lenses 11 and 12, a first and second condenser lens 11 and 12, which condense light from a light source onto four surfaces of a recording medium, a movable part 1, and a lens support mechanism. 2, and first and second focus actuators 81 and 82 as first and second focus drive units.

The two condensing lenses 11 , 12 are mounted on the same movable part 1 .

The lens support mechanism 2 supports such a movable part 1 on the recording medium 4.
This is a support mechanism that supports the recording medium movably in the focusing direction perpendicular to the surface thereof, and also supports the recording medium movably in the rotational direction about the tracking direction parallel to the four surfaces of the recording medium.

The first and second focus actuators 81 and 82 are installed to drive two different parts of the movable part 1, and the movable part 1 is also provided with a tracking actuator 9 used for movement and positioning in the tracking direction. It is being

Further, as shown in FIG. 1, the arm portion 3, the bearing 5,
The optical head housing 6 includes an optical system 7 and two condensing lenses 11.
Each beam 71 , 73 for 12 is emitted from the optical system 7 .

Further, it will be explained in detail.

First and second condensing lenses 11 fixed on the movable part 1
．． 12 is an arm section using a lens support mechanism 2 whose one end is connected to the movable section 1 via one temporary spring 21 and the other end is connected to the arm section 3 via two parallel plate springs 22. 3
It is now supported by Lens support mechanism 2
consists of a leaf spring 21, two parallel leaf springs 22, and a connecting member 23 that connects them. Both the leaf spring 21 and the two parallel leaf springs 22 are arranged in a direction having a surface parallel to the recording medium 4. As a result, the movable part 1 operates in a rotational direction with the focusing direction perpendicular to the surface of the recording medium 4 (indicated by arrow a in the figure) and the tracking direction parallel to the axis (direction perpendicular to the plane of the paper). I can do it. The first and second condensing lenses 11 and 12 are arranged on the same movable part 1, with the focusing direction being the optical axis, and close to each other in a direction perpendicular to the tracking direction.

Here, FIG. 2 shows the first and second condensing lenses 11°12
and first and second focus actuators 81°82
FIG. 2 is a diagram for explaining the positional relationship between the two and one configuration example of the first and second focus actuators.

As shown in FIG. 2, first and second condensing lenses 11.
A first coil 811 wound in a flat donut shape is mounted on the side surface of the movable part 1 on which the movable part 12 is mounted, on the first condensing lens 11 side.
A second coil 821 having the same shape as the first coil is attached to the side surface of the second condensing lens 12 examples. and,
One side of each of these donut-shaped coils 8o and a2i, on which the conductive wire is arranged in the tracking direction, is arranged in a magnetic circuit gap (not shown), and each coil 811
, 821 to generate a force in the focusing direction.

Furthermore, as shown in FIG. 1, the arm section 3 is connected to the optical head housing 6 by a bearing 5 that supports the rotation direction about the focusing direction, and as a result, the movable section 1 can also move in the tracking direction. It is possible.

This lens actuator is a lens actuator that moves a condensing lens that focuses light from a light source onto four surfaces of a recording medium in a focusing direction perpendicular to the four surfaces of the recording medium and in a tracking direction parallel to the four surfaces of the recording medium. 1
Two condensing lenses 11 and 12 mounted on the top, a lens support mechanism 2 that movably supports the movable part 1 in the focusing direction and also movably in the rotational direction about the tracking direction, and the movable part 1. First and second focus actuators 81, 8 that drive two different locations of
2, and the focusing lenses 11, 12 are moved not only in the focusing direction and the tracking direction, but also in the rotational direction about the tracking direction.

Next, the operation will be explained.

When the beams 71° 73 are emitted from the optical system 7 in the optical head housing 6, the first beam 7 emitted from the optical system 7
1 is condensed onto the recording medium 4 via the first condensing lens 11 to form a minute first light spot 72 . The second beam 73 emitted from the optical system 6 is condensed onto the recording medium 4 via the second condenser lens 12 to form a minute second light spot 74 .

Since two light spots 72 and 74 can be formed simultaneously on the recording medium 4 in this way, when rewriting information, one of the light spots 72 and 74 can be formed as described below.
2 can be used for erasing, and the other light spot 74 can be used for writing.

Focus control for these two light spots 72 and 74 is performed by moving the movable portion l by combining an operation in the focusing direction and an operation in the rotation direction about the tracking direction.

That is, focus control to optimally focus the first and second beams 71.73 on the surface of the recording medium 4 is performed by the first and second focus actuators 81.82 provided for the movable part 1 and the optical First and second beams 71 and 73 respectively corresponding to the first and second beams provided in the system 7
This is performed by a servo-controlled '4B mechanism consisting of a position detector (not shown) in the focusing direction a and an external control circuit. First and second focus actuators 81.
82 is installed so as to drive a position shifted toward the first condensing lens 11 and a position shifted toward the second condensing lens 12 with respect to the center of gravity of the movable part 1, and both actuators A driving force in a direction to rotate the movable part 1 is generated in accordance with the difference between the generated forces of 81 and 82. As a result, the movable part 1
is driven in the focusing direction, and the two condensing lenses 11.1 are driven by the aforementioned servo control mechanism.
The condenser lens 11 is configured such that the focal planes of the two focal planes of the two focal planes are correctly aligned on the surface of the recording medium 4 according to the waviness of the surface of the recording medium 4.
．． 12 is moved and focus control is performed.

On the other hand, the movement and positioning of the first and second light spots 72 and 74 in the tracking direction is performed by a tracking actuator 9 provided for the movable part 1 and one or two of the tracking actuators provided in the optical system 7. This is done by a separate servo mechanism consisting of a position detector (not shown), a hand positioner mechanism (not shown) that moves the entire head, and an external control circuit.

Regarding this tracking control, even if there are two condensing lenses, since they are mounted on the same movable part 1, as shown in FIG. All you have to do is set it up.

In this way, the two condensing lenses 11 and 12 can be moved not only in the focusing direction and the tracking direction but also in the rotational direction as described above, so even if they are mounted on the same movable part 1, the recording medium Two light spots 7 that can correspond to the undulations of 1 and are sufficiently focused on one surface of the recording medium.
2.74, it is possible to accurately focus even if the recording medium 1 causes waviness, and even if it has two condensing lenses 11 and 12, the common movable part 1
The first and second focus actuators 81.
82 and a tracking actuator 9,
Unlike when simply using two sets of lens actuators in combination, the head configuration does not become complicated, and the formed light spots 72 and 74 are not too far apart, and the light spots 72 and 74 are spaced several millimeters apart. ) 72 and 74 can easily realize a lens actuator with a simple configuration that can control two adjacent condenser lenses 11 and 12.

In the case of rewriting information, the two spots 72 and 74 formed as described above are used together, one for erasing and one for recording.

Erasing and recording on the recording medium 4 is performed by direct current irradiation of the first beam 71 in accordance with an input signal from an external control device, which moves the recording medium 4 from the first condensing lens 11 to the second condensing lens 12. As the first light spot 72 moves in the direction of the arrow in FIG. By modulating the beam 73, a second light spot 7 follows immediately after the first light spot 72.
4, information is recorded in the area where the first light spot 72 has been erased.

In this way, among the two optical spoilers 1-72.74 formed by the two condensing lenses 11.12 at an interval of about several n, the laser beam is irradiated in a direct current manner at the leading optical spot 72. erase operation and follow the light spot 74.
By modulating the laser beam and recording, the erasing and recording operations can proceed almost in parallel with only a slight delay, making it possible to rewrite information at high speed with as little wasted time as possible. becomes.

In this embodiment, an example was explained in which one end of one plate spring 21 is connected to the movable part 1 and one ends of two parallel plate springs 22 are connected to the arm part 3 as the lens support mechanism 2. Conversely, one end of two parallel plate springs is connected to the movable part 1,
Even in a configuration where one end of one temporary spring is connected to the arm part 3,
The basic effect remains the same, and a lens support mechanism with this configuration may be used.

〔Effect of the invention〕

As explained above, according to the present invention, a pair of focus drive sections and a set of tracking drive sections, which are almost the same in size as the focus actuator in the conventional lens actuator that drives one condenser lens, are used to drive two condensing lenses. In order to operate two condensing lenses, it is possible to control the two condensing lenses with a lens actuator having a simple configuration.

The formation of two light spots on the recording medium by the two condensing lenses is accurate, and even on a recording medium that causes undulations, accurate focusing can be performed, and two adjacent light spots can be formed at intervals of several cranes. A lens actuator having a condensing lens can be easily obtained, and with this, when rewriting information, the information already recorded in the preceding light spot is erased, and the following light spot 7 is erased in parallel. )
Information can be recorded quickly, and information can be rewritten faster with less wasted time.

[Brief explanation of the drawing]

FIG. 1 shows an example of a lens actuator according to the present invention; FIG. 2 is a perspective view showing an example of the configuration of the movable portion of FIG. 1; 1... Movable part 2... Lens support mechanism 3... Arm part 4... Recording medium 5... Bearing 6... Optical head housing 7... Optical system 9... Tracking actuator 11, 12... Converging lenses 71, 73... Light beams 72, 74... Light spots 81, 82... Focus actuator 811,
821...Coil

Claims (1)

[Claims] (1) In a lens actuator that moves a condenser lens that condenses light from a light source onto a recording medium in a focusing direction perpendicular to the surface of the recording medium and in a tracking direction parallel to the surface of the recording medium, two actuators mounted on the same movable part are used. A condensing lens, a lens support mechanism that movably supports the movable part in the focusing direction and also movably in a rotational direction about the tracking direction, and drives two different parts of the movable part. A lens actuator comprising first and second focus drive sections.