JPH09198708A - Actuator for optical pickup - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform a recording and a reproducing with resprect to recording medium having different recording densities by providing respective lenses to be used for light beams having different wavelengths in an actuator main body. SOLUTION: When a first light beam is made incident on an objective lens 4, a servo circuit performs focus servo and tracking servo controls with respect to the lens 4 by controlling the actuator main body 3. Moreover, when a second light beam is made incident on an objective lens 5, the servo circuit performs focus servo and tracking servo controls with respect to the lens 5 by controlling the main body 3. Thus, the actuator main body 3 in which two objective lenses are arranged is controlled in accordance with respectively different wave lengths by one servo circuit.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pickup for recording and reading information on an information recording medium.

[0002]

2. Description of the Related Art As the density of information recording media has increased, development of high density information recording media and recording / reproducing devices for recording and reproducing by using a light beam having a wavelength of about half that of conventional ones has been advanced. When the software is enhanced due to the spread of these, the demand for a recording / reproducing apparatus that can use both a conventional information recording medium disc and a high density information recording medium will increase.

Conventionally, in order to use these information recording media, respective dedicated recording / reproducing devices have been used, or respective dedicated optical pickups and control devices have been provided in the recording / reproducing device and switched and used. .

[0004]

However, if the recording / reproducing apparatus dedicated to each information recording medium is used,
The recording / reproducing device becomes large. Further, when two types of optical pickups are provided in the recording / reproducing apparatus to form a combined type apparatus, there is a drawback that the number of parts increases and the structure becomes complicated.

Therefore, an object of the present invention is to provide a combined type recording / reproducing apparatus for recording / reproducing information recording media having different recording densities, which is not so different from the conventional recording / reproducing apparatus.

[0006]

Therefore, according to the present invention of claim 1, an objective lens for converging a light beam into a beam spot diameter adapted to recording and reproducing on an information recording medium, and an actuator main body for holding the objective lens. An optical pickup actuator comprising: a focus coil and a tracking coil installed in the actuator body; and a magnetic circuit for driving the focus coil and the tracking coil. The actuator body uses a light beam of a first wavelength. It is characterized by including a first objective lens and a second objective lens used for a light beam of a second wavelength.

According to the present invention, since a plurality of objective lenses corresponding to different wavelengths can be arranged in one actuator, one drive and control circuit can control the light beams of two optical path systems. it can.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described with reference to the top view of FIG. 1 and the vertical sectional view of FIG. FIG. 1 is a top view showing an embodiment of an optical pickup actuator of the present invention. FIG. 2 is a vertical sectional view showing an embodiment of the optical pickup actuator of the present invention.

In FIG. 1, an actuator body 3 which is slidably and rotatably supported is provided on a shaft 2 which is vertically erected on the yoke body 1. Then, in the actuator body 3, a plurality of objective lenses are arranged side by side in the tangential direction of the track of the information recording medium (not shown), and at positions symmetrical about the axis 2. In this embodiment, as the plurality of objective lenses, the first objective lens 4 corresponding to the wavelength of the first light beam conventionally used, and approximately half of the first light beam conventionally used. Two second objective lenses 5 corresponding to the second light beam having the wavelength of are arranged. The light beam is a laser beam emitted from a semiconductor laser.

Further, the yoke body 1 and the actuator body 3 are provided with driving means for sliding and rotating the actuator body 3 with respect to the shaft 2. The drive means is composed of a magnetic circuit of a coil and a magnet, and sliding and rotation are controlled by a current supplied from a servo circuit (not shown). A tracking coil 6 and a focus coil 7 are attached to the actuator body 3, and a tracking coil magnet 10 and a focus coil magnet 11 are fixed to the yoke body 1 at positions facing the tracking coil 6 and the focus coil 7. ing.

The actuator body 3 and the yoke body 1 are connected by a rubber damper 8 to support the actuator body 3. Then, the yoke body 1 is provided with through holes 9 into which the light beams are incident, at positions facing the respective objective lenses.

As described above, the first objective lens 4 and the second objective lens 5 used for the light beams of different wavelengths are arranged in the actuator body 3 at symmetrical positions with respect to the axis 2. . The actuator body 3 includes a tracking magnetic circuit including the yoke body 1, the tracking coil 6, and the tracking coil magnet 11, and a focusing magnetic circuit including the yoke body 1, the focus coil 7, and the focus coil magnet 11. And are provided.

When the first light beam is incident on the first objective lens 4, the servo circuit controls the actuator body 3 to perform focus servo and tracking servo control on the first objective lens 4. When the second light beam is incident on the second objective lens 5, the servo circuit controls the actuator body 3 to perform focus servo control and tracking servo control on the second objective lens 5. That is, one servo circuit can control the actuator body in which the two objective lenses are arranged according to different wavelengths.

The optical pickup actuator having the above structure can irradiate optical disks having different recording densities with light beams of different wavelengths without increasing the number of optical pickups and the mechanisms and circuits for driving and controlling the optical pickups.

Further, as shown in FIG. 2, in the fixed frame 12 of the second objective lens 5, the upper end surface of the first objective lens 4 and the upper end surface of the second objective lens 5 are flush with each other. It is arranged. That is, the fixed frame 12 performs the function of adjusting the heights of the upper ends of the first objective lens 4 and the second objective lens 5 protruding from the actuator body 3, and the balance adjustment with respect to the axis 2 of the actuator body 3. Combines functions.

That is, when the sizes of the first objective lens 4 and the second objective lens 5 are different, the first objective lens 4
From the upper end surface of the first objective lens 4 to the information recording medium (hereinafter referred to as an optical disk), and the upper end surface of the second objective lens 4 and the optical disk are different from each other. It is closer to the optical disc than the upper end surface of the objective lens 5 of. At this time, if the second objective lens 5 is adjusted to the focus position, the first objective lens 4 may erroneously come into contact with the optical disc and damage the optical disc. Therefore, the fixed frame 12 adjusts the height position with respect to the actuator body 3 so that the upper end surfaces of the first objective lens 4 and the second objective lens 5 are flush with each other.

When the weights of the first objective lens 4 and the second objective lens 5 are different, the first objective lens 4 side and the second objective lens 5 side of the actuator body 3 are centered around the axis 2. The balance may be lost, the actuator body 3 may not be able to slide and rotate on the shaft 2, and the operation may be slow. Therefore, the fixed frame 12 has a function of adjusting the balance between the first objective lens 4 and the second objective lens 5 with respect to the axis 2.

The fixed frame 12 may be molded integrally with the second objective lens 5. That is, the fixed frame 12
Fixes the second objective lens 5 to the actuator main body 3, and at the same time, the first objective lens 4 and the second objective lens 5 are
It is sufficient to adjust the height position and balance of the.

In the optical pickup actuator having the above structure, when a plurality of objective lenses are arranged on the actuator body that slides and rotates about the axis, at least one objective lens among the plurality of objective lenses is
The actuator is fixed to the actuator body via the fixing frame. Therefore, even with a plurality of objective lenses having different outer shapes or optical specifications, the height position or the optical position can be adjusted with respect to the optical disc. Further, even a plurality of objective lenses having different weights can be arranged in a balanced state with respect to the axis on which the actuator body slides and rotates.

[0020]

As described above, according to the present invention, it is possible to provide a combined recording / reproducing apparatus for recording / reproducing information recording media having different recording densities, which is not so different from the conventional recording / reproducing apparatus.

[Brief description of drawings]

FIG. 1 is a top view showing an embodiment of an optical pickup actuator of the present invention.

FIG. 2 is a longitudinal sectional view showing an embodiment of the optical pickup actuator of the present invention.

[Explanation of symbols]

 1 ・ ・ ・ Yoke body 2 ・ ・ ・ Axis 3 ・ ・ ・ Actuator body 4 ・ ・ ・ First objective lens 5 ・ ・ ・ Second objective lens 6 ・ ・ ・ Tracking coil 7 ・ ・ ・ Focus coil 8 ・ ・・ Rubber damper 9 ・ ・ ・ Through hole 10 ・ ・ ・ Tracking coil magnet 11 ・ ・ ・ Focus coil magnet 12 ・ ・ ・ Fixed frame

Claims (1)

[Claims] 1. An objective lens for condensing a light beam into a beam spot diameter suitable for recording and reproduction on an information recording medium, an actuator main body for holding the objective lens, a focus coil and tracking installed in the actuator main body. In an actuator for an optical pickup including a coil and a magnetic circuit for driving the focus coil and the tracking coil, a first objective lens used for a light beam of a first wavelength and a second wavelength An actuator for an optical pickup, comprising: a second objective lens used for a light beam.