JPH11203700A - Optical pickup - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical pickup allowing both of changing over a direction of a light beam and a tracking control by one galvanometer mirror. SOLUTION: An optical pickup has a galvanometer mirror 120 deflecting a beam of light from a light source/detection part 110, two start-up mirrors 132, 134, and two objective lenses 142, 144. The two start-up mirrors 132 and 134 are mutually located on the opposite side to the light beam 170. The objective lens 142 is located above the start-up mirror 132 and faces a recording medium 152 above the optical pickup, and the objective lens 144 is located under the start-up mirror 134 and faces a recording medium 152 under the optical pickup. The galvanometer mirror 120 is located relatively near the two objective lenses 142, 144 and supported to be rocked, and its rocking axis 122 is extending in the direction almost perpendicular to the surfaces of the recording media 152, 154.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pickup used for an information recording and / or reproducing apparatus, and more particularly to an optical pickup provided with two light collecting means for condensing a light beam on a recording medium, for example, an objective lens. .

[0002]

2. Description of the Related Art As one type of optical pickup, there is a type provided with two condensing means for condensing a light beam on a recording medium. This type of optical pickup is, for example, for selectively condensing a light beam on each recording layer of a recording medium having recording layers on both sides, or for two recording media disposed above and below the optical pickup. To selectively focus the light beam,
Alternatively, two focusing means are provided to focus the light beam on different types of recording media to be exchanged.

Alternatively, two light collecting means are provided to share the access range of the recording medium with the two light collecting means, to reduce the movement amount of the optical pickup, and to improve the access speed.

[0004] An optical pickup having two condensing means as described above has a mechanism for directing a light beam emitted from a light source unit to one of the two condensing means.
This mechanism can be realized by various elements and structures, one of which is a galvanomirror.

Japanese Patent Laid-Open Publication No. Hei 3-25733 discloses, as a conventional example, a fixed optical unit for emitting a light beam and a movable optical unit having two objective lenses, and a galvanomirror provided in the fixed optical unit. An optical pickup is disclosed that directs a light beam to one of the objective lenses in a movable optic.

[0006]

It is desired that the optical pickup be reduced in size and weight. Therefore, it is preferable that the number of parts is small. Therefore, a configuration in which one component or element has a plurality of functions is excellent in reducing the number of components.

For example, in an optical pickup provided with a galvanomirror for switching the direction of a light beam, a configuration in which tracking control is left to this galvanomirror can be considered.

However, as described above, Japanese Patent Application Laid-Open No. 3-257
In the optical pickup disclosed in No. 33 as a conventional example, since the distance between the objective lens and the galvanometer mirror is wide, the light beam largely moves at the position of the objective lens even with a slight change in the inclination of the reflection surface of the galvanometer mirror. I do.

In the tracking control, it is preferable that the incident angle of the light beam with respect to the objective lens can be largely changed. However, in the above-described optical pickup, the light beam is moved from the pupil of the objective lens before obtaining a large change in the incident angle of the light beam. It will come off. Therefore, the tracking range of the galvanometer mirror was narrow, and good tracking servo characteristics could not be obtained.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an optical pickup which performs both switching of a light beam direction and good tracking control with one galvanomirror. It is.

[0011]

An optical pickup according to the present invention comprises a light source for emitting a light beam, two light condensing means for condensing the light beam on a recording medium, and two light beams from the light source. A galvanomirror for directing light to one of the condensing means, and the galvanomirror is located near the two condensing means, and the light beam is two-dimensionally swung by largely shaking the reflecting surface of the galvanomirror. The tracking control is performed by selectively directing one of the two light condensing means and swinging the reflecting surface of the galvanomirror in a narrow range.

In one embodiment, for example, each condensing means comprises an objective lens arranged opposite to the recording medium and a rising mirror for deflecting the light beam from the galvanometer mirror toward the objective lens. , The two mirrors are separated in a direction parallel to the plane of the recording medium,
The light beam emitted from the light source unit reaches the galvanometer mirror through the space between the two rising mirrors.

In another embodiment, for example, one of the light-collecting means is constituted by an objective lens arranged to face the recording medium, and the other light-collecting means is arranged to face the recording medium. It comprises an objective lens and a rising mirror for deflecting the light beam from the galvanometer mirror toward the objective lens.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. First, an optical pickup according to the first embodiment will be described with reference to FIG. As shown in FIG. 1A, the optical pickup includes a light source / detector 110 that emits a light beam and detects a return light beam, and a galvanomirror 120 that deflects the light beam from the light source / detector 110. , Two launch mirrors 1
32 and 134 and two objective lenses 142 and 144.

The objective lens 142 forms one condensing means, and the objective lens 144 forms another condensing means.
Although not shown, the light source / detection unit 110 includes a light source unit that emits a light beam, a detection unit that detects a return light beam, and a beam splitter that separates the return light beam and guides the return light beam to the detection unit. .

Start-up mirror 132 and start-up mirror 1
Numeral 34 is spaced apart in a direction parallel to the surfaces of the recording media 152 and 154, and from the light source / detection unit 110 to the galvanomirror 12
0 so as to sandwich the light beam 170 going to zero.
0 are opposite to each other. Therefore, the light beam emitted from the light source / detection unit 110 reaches the galvanometer mirror 120 after passing between the two rising mirrors 132 and 134.

As shown in FIG. 1B, the objective lens 142 is located above the rising mirror 132, and the objective lens 144 is located below the rising mirror 134. The objective lens 142 faces the recording medium 152 disposed above the optical pickup, and the objective lens 144
It faces the recording medium 154 arranged below the optical pickup.

The galvanometer mirror 120 is located relatively close to the two objective lenses 142 and 144, and is supported so as to be swingable about a swing shaft 122 as a swing center. Swing shaft 12
Reference numeral 2 extends in a direction substantially perpendicular to the surfaces of the recording media 152 and 154.

The above-described optical member is housed or attached to the housing 160. The housing 160 includes the objective lens 1
Any structure can be used as long as the tracks 42 and 144 are movably supported so as to cross the tracks provided on the recording media 152 and 154, preferably substantially vertically. In the present embodiment, the swing arm rotates around the shaft 161.

Here, the specific structure of the galvanometer mirror 120 will be described with reference to FIG. As shown in FIG. 7A, the galvanometer mirror 120 includes a mirror unit 710 having a reflection surface, and a pair of spring units 720 supporting the mirror unit 710.
And a frame portion 730 for supporting the same.
The mirror part 710, the spring part 720, and the frame part 730
It is formed integrally by etching the silicon substrate.

Further, the galvanometer mirror 120 has a coil pattern 740 which goes around the periphery of the mirror section 710, and a pair of magnets 750 which are supported on the upper and lower side end faces of the mirror section 710 at intervals.

The coil pattern 740 extends in the spring portion 720 and terminates at the power supply pad 742. The coil patterns 740 are provided on both surfaces of the mirror unit 710, as shown in FIG. For example, the coil pattern 740 is a copper pattern, which is formed by etching a copper thin film.

The two magnets 750 are fixed to the frame 730 such that magnetic poles of opposite polarities face each other.
The mirror unit 710 is located between them. In the galvanomirror 120, current is supplied to the coil pattern 740 via the power supply pad 742. Coil pattern 740
Of the coil pattern 740 provided on the peripheral portion of the mirror portion 710, the portion extending in parallel with the magnet 750 is perpendicular to the reflection surface 712 of the mirror portion 710 in the upside down direction. In the direction you want. As a result, the spring section 720 is twisted, and the reflection surface 712 of the mirror section 710 is inclined.

The amount by which the reflection surface 712 of the mirror section 710 is inclined, that is, the inclination angle, changes depending on the value of the current flowing through the coil pattern 740. The direction in which the reflection surface 712 of the mirror unit 710 is inclined corresponds to the direction of the current flowing through the coil pattern 740.

The galvano mirror 120 is actually such a structure, but is schematically illustrated in FIG. Further, in other embodiments, the galvanomirror is schematically illustrated in the drawings relating thereto, but the actual structure is the same as that of the galvanomirror 120 in FIG.

As shown in FIGS. 1A and 1B, the light beam 170 emitted from the light source / detection unit 110
Is set up by a galvanomirror 120 according to the orientation of the surface thereof, by a rising mirror 132 or a rising mirror 13.
4 is reflected.

Light beam 1 heading to rising mirror 132
Numeral 72 is reflected by the rising mirror 132, condensed by the objective lens 142, and forms a light spot on the recording surface of the recording medium 152. In addition, the starting mirror 134
Is reflected by the rising mirror 134 and then condensed by the objective lens 144 to form a light spot on the recording surface of the recording medium 154.

That is, the light beam 170 is changed by greatly changing the inclination of the reflection surface of the galvanometer mirror 120.
It is selectively guided to either the objective lens 142 facing the recording medium 152 located above the optical pickup or the objective lens 144 facing the recording medium 154 located below the optical pickup.

The light spot is formed by a galvanometer mirror 12.
Tracking control is performed by changing the inclination of the 0 reflection surface in a narrow range. Here, the narrow range means a range in which the incident light beam does not deviate from the objective lens.

Specifically, the incident angle of the light beam 172 toward the objective lens 142 with respect to the objective lens 142 can be changed by changing the inclination of the reflection surface of the galvanomirror 120 to be small. As a result, the objective lens 142
The light spot formed on the recording medium 152 facing the image moves along the tracking direction indicated by an arrow in the drawing. Although the movement direction of the light spot does not exactly coincide with the tracking direction, this does not matter in tracking control. The same applies to the light beam 174 directed to the objective lens 144.

The galvanomirror 120 is located relatively close to the two objective lenses 142 and 144, and the optical path length from the galvanomirror 120 to the objective lenses 142 and 144 is relatively short. Even if the inclination is changed relatively large, the objective lenses 142 and 1
Since the deviation of the light beam incident on 44 is small, the light spot formed on the recording media 152 and 154 during the tracking control can be relatively moved.

The light reflected by the recording media 142 and 144 returns in the reverse direction of the incident optical path, and finally enters a detector for detecting a return light beam. The detector generates information necessary for information reproduction, tracking control, and the like based on the return light beam.

As can be seen from the above description, in this optical pickup, the direction of the light beam is switched by greatly changing the inclination of the reflection surface of the galvanometer mirror 120, and thereby the objective lens on which the light beam is incident is changed. The recording medium to be accessed is switched as a result. Tracking control is performed by controlling the inclination of the reflection surface of the galvanometer mirror 120 in a narrow range.

The galvanomirror 120 and the light source 110
Between them, the objective lenses 142 and 144 as the light condensing means were positioned. That is, the objective lens 142,
The light beam 170 emitted to the 144 side is temporarily
After passing through the positions 42 and 144, the light beam is made incident on the galvanomirror 120, and the light beam reflected by the galvanomirror 120 is reflected by the objective lenses 142 and 144 (the light source unit 110).
And reflected by the rising mirrors 132 and 134 to be incident on the objective lenses 142 and 144. Since the light from the light source unit 110 is folded back by the galvanomirror 120, the galvanomirror 120 is
2,144, and galvanometer mirror 1
At 20, a light beam can be selectively directed to one of the two objective lenses. For example, in a conventional configuration in which the rising mirrors 132 and 134 are galvano mirrors, the light beam cannot be selectively directed to the two objective lenses by the galvanomirrors.

Further, two rising mirrors 132, 13
4 is displaced in a direction parallel to the recording surface of the recording medium 152, and an optical path is provided between the two.
Is located. Therefore, the light beam 170 and the two rising mirrors 132 and 134 can be arranged on the same plane. Therefore, the device can be made thin.

Further, a galvanomirror is used as an optical path switching means for selectively directing a light beam to the two objective lenses 142 and 144, and the galvanomirror doubles as a tracking device. Therefore, the two objective lenses 14
Since the tracking drive device for 2,144 and the optical path switching means can be performed by one galvanomirror, it is suitable for miniaturization, weight reduction, simplification, and cost reduction of the device.

Next, an optical pickup according to a second embodiment will be described with reference to FIG. As shown in FIG. 2A, the optical pickup includes a galvano mirror 220 that deflects a light beam emitted from a light source (not shown).
And two rising mirrors 232 and 234, and two objective lenses 242 and 244.

Raising mirror 232 and objective lens 242
Constitute one condensing unit, and the rising mirror 234 and the objective lens 244 constitute another condensing unit. FIG.
As shown in (B), the objective lens 242 is located above the rising mirror 232, and the objective lens 244 is located below the rising mirror 234. Objective lens 2
Reference numeral 42 faces a recording medium disposed above the optical pickup, and the objective lens 244 faces a recording medium disposed below the optical pickup.

The galvanometer mirror 220 is located relatively close to the two objective lenses 242 and 244, and is supported so as to be swingable about a swing shaft 222 as a swing center. Swing shaft 22
2 is inclined with respect to a direction substantially perpendicular to the surface of the recording medium.

Starting mirror 232 and starting mirror 2
As can be seen from FIG. 2A, reference numerals 34 are arranged close to each other in a direction parallel to the surface of the recording medium disposed above and below the optical pickup, and are positioned on both sides of the light beam 270 toward the galvanometer mirror 220. doing. As can be seen from FIG. 2 (B), their main parts are the galvanomirror 2
It contains a light beam 270 going to 20 and is located below a plane parallel to the plane of the recording medium.

Further, as shown in FIG. 2A, the rising mirror 232 and the rising mirror 234 have chamfers 232a at their upper ends inside so as not to obstruct the light beam 270 toward the galvano mirror 220. , 234
a is provided.

Since the light beam 270 on the rising mirrors 232 and 234 has an elliptical shape as shown in FIG. 2A, the chamfers 232a and 234a do not hinder the light beam 270.

As shown in FIGS. 2A and 2B, the light beam 270 emitted from the light source unit is turned by the galvanomirror 220 into the rising mirror 232 or the rising mirror 232 depending on the direction of the surface. The light is reflected toward the raising mirror 234.

The light beam 272 reflected by the rising mirror 232 is condensed by the objective lens 242 to form a light spot on a recording medium disposed above the optical pickup. The light beam 274 reflected by the rising mirror 234 is condensed by the objective lens 244 to form a light spot on a recording medium disposed below the optical pickup.

That is, the light beam 270 changes the inclination of the reflecting surface of the galvanometer mirror 220 greatly,
It is directed to either the objective lens 242 facing the recording medium located above the optical pickup or the objective lens 244 facing the recording medium located below the optical pickup.

The light spot formed on the recording medium is moved in a direction crossing a track formed on the recording medium, that is, in a tracking direction by changing the inclination of the reflection surface of the galvano mirror 220 in a narrow range. You. That is, tracking control is performed by shaking the reflecting surface of the galvanometer mirror 220 in a narrow range.

The galvanomirror 220 has an objective lens 242
And 244, the optical path length from the galvanometer mirror 220 to the objective lenses 242 and 244 is relatively short. For this reason, even if the inclination of the reflecting surface of the galvanometer mirror 220 is changed relatively large, the objective lens 242
The deviation of the light beam incident on the recording medium 244 is small, so that the light spot formed on the recording medium during the tracking control can be moved relatively large.

The light reflected by the recording medium returns in the reverse direction of the incident light path, and finally enters a detection unit for detecting the return light beam. The detector generates information necessary for information reproduction, tracking control, and the like based on the return light beam.

As described above, in this optical pickup, the objective lens on which the light beam is incident is switched by greatly changing the inclination of the reflection surface of the galvanometer mirror 220, and the reflection surface of the galvanometer mirror 220 is switched. Tracking control is performed by controlling the inclination by changing it in a narrow range.

In the present embodiment, the two rising mirrors 232 and 234 are arranged side by side, and the light beam passes over them. One objective lens 24
The distance between the 2,244 optical axes can be made smaller than in the first embodiment.

An optical pickup according to the third embodiment will be described with reference to FIG. As shown in FIG. 3A, the optical pickup includes a galvanomirror 320 for deflecting a light beam from the light source unit and one rising mirror 33.
2 and two objective lenses 342 and 344.

The objective lens 342 constitutes one condensing means, and the objective lens 344 constitutes another condensing means.
As shown in FIG. 3B, the objective lens 342 is located above the rising mirror 332, and faces the recording medium 352 arranged above the optical pickup. The objective lens 344 is located below the galvanometer mirror 320 and faces the recording medium 354 arranged below the optical pickup.

The galvanometer mirror 320 is located relatively close to the two objective lenses 342 and 344, and is supported so as to be swingable about a swing shaft 322 as a swing center. Swing shaft 32
As shown in FIG. 3A, 2 is inclined by approximately 45 degrees with respect to the surfaces of the recording media 352 and 354.

As shown in FIGS. 3A and 3B, the light beam 370 emitted from the light source unit is directed to the rising mirror 332 by the galvanometer mirror 320 according to the direction of the surface. Or directly the objective lens 3
It is reflected towards 44.

The light beam 372 reflected by the rising mirror 332 is condensed by the objective lens 342 and forms a light spot on the recording surface of the recording medium 352. The light beam 374 directed to the objective lens 344 is condensed by the objective lens 344 to form a light spot on the recording surface of the recording medium 354.

That is, the light beam 370 changes the inclination of the reflecting surface of the galvanomirror 320 greatly,
The objective lens 342 facing the recording medium 352 disposed above the optical pickup or the objective lens 344 facing the recording medium 354 disposed below the optical pickup.
To either one of

The light spot formed on the recording medium is moved in a direction crossing a track formed on the recording medium, that is, in a tracking direction by changing the inclination of the reflection surface of the galvano mirror 320 within a narrow range. You. That is, tracking control is performed by swinging the reflecting surface of the galvanometer mirror 320 in a narrow range.

The galvanomirror 320 has an objective lens 342
And 344, the optical path length from the galvanomirror 320 to the objective lenses 342 and 344 is relatively short. Therefore, even if the inclination of the reflecting surface of the galvanometer mirror 320 is changed relatively large, the objective lens 342
And 344 are small. As a result, the light spot formed on the recording medium can be moved relatively large.

The light reflected by the recording medium travels back through the incident optical path and finally enters a detector for detecting the return light beam. The detector generates information necessary for information reproduction, tracking control, and the like based on the return light beam.

As can be understood from the above description, this optical pickup switches the objective lens on which the light beam enters by largely changing the inclination of the reflection surface of the galvanometer mirror 320, and changes the reflection surface of the galvanometer mirror 320. Tracking control is performed by controlling the inclination by changing it in a narrow range.

In this embodiment, the galvanomirror 32
The light beam 374 reflected at 0 was directly incident on the objective lens 344. Therefore, the number of startup mirrors can be reduced.

An optical pickup according to a fourth embodiment will be described with reference to FIG. As shown in FIG. 4A, the optical pickup includes a light source unit 41 for emitting a light beam.
2, a detection unit 416 for detecting the return light beam, a beam splitter 414 for separating the return light beam and guiding the return light beam to the detection unit 416, and a galvanometer mirror 420 for deflecting the light beam from the light source unit 412. It has mirrors 432 and 434 and two objective lenses 442 and 444.

The rising mirror 432 and the objective lens 442
Constitute one condensing means, and the rising mirror 434 and the objective lens 444 constitute another condensing means. In addition,
Light source 412, beam splitter 414, and detector 41
6 corresponds to the light source / detection unit 110 in the first embodiment.

The starting mirror 432 and the starting mirror 4
Numerals 34 are arranged close to each other in a direction parallel to the surface of the recording medium disposed above and below the optical pickup.
2 is located on the same side as the light beam 470 going to the galvanometer mirror 420.

As shown in FIG. 4B, the objective lens 442 is located above the rising mirror 432, and faces the recording medium disposed above the optical pickup. The objective lens 444 is located below the rising mirror 434, and faces the recording medium disposed below the optical pickup.

The galvanometer mirror 420 is located relatively close to the two objective lenses 442 and 444, and is supported so as to be swingable about a swing shaft 422 as a swing center. Swing shaft 42
Reference numeral 2 extends in a direction substantially perpendicular to the surface of the recording medium disposed above and below the optical pickup.

As shown in FIGS. 4A and 4B, the light beam 470 emitted from the light source unit 412 is changed by the galvanomirror 420 in accordance with the direction of its surface.
The light is reflected toward the rising mirror 432 or the rising mirror 434.

The light beam 472 reflected by the rising mirror 432 is condensed by the objective lens 442, and forms a light spot on the recording surface of the recording medium located above the objective lens 442. Further, the light beam 474 reflected by the rising mirror 434 is condensed by the objective lens 444 and forms a light spot on the recording surface of the recording medium located therebelow.

That is, the light beam 470 can change the inclination of the reflecting surface of the galvanometer mirror 420 greatly,
The light is selectively guided to one of the objective lens 442 facing the recording medium located above the optical pickup and the objective lens 444 facing the recording medium located below the optical pickup.

The light spot formed on the recording medium is moved in a direction crossing a track formed on the recording medium, that is, in a tracking direction by changing the inclination of the reflection surface of the galvano mirror 420 in a narrow range. You. That is, tracking control is performed by shaking the reflecting surface of the galvanometer mirror 420 in a narrow range.

The galvanomirror 420 has an objective lens 442.
And 444, the optical path length from the galvanometer mirror 420 to the objective lenses 442 and 444 is relatively short. For this reason, even if the inclination of the reflection surface of the galvanometer mirror 420 is changed relatively large, the objective lens 442
And 444 are small. As a result, the light spot formed on the recording medium can be moved relatively large.

The light reflected by the recording medium returns in the reverse direction of the incident optical path, and finally enters a detector for detecting the return light beam. The detector generates information necessary for information reproduction, tracking control, and the like based on the return light beam.

As can be understood from the above description, this optical pickup switches the objective lens on which the light beam enters by largely changing the inclination of the reflection surface of the galvanometer mirror 420, and changes the reflection surface of the galvanometer mirror 420. Tracking control is performed by controlling the inclination by changing it in a narrow range.

In this embodiment, two objective lenses 442,
The distance between the optical axes 444 can be reduced. Further, since the light beam passes on the side of the rising mirror (the direction parallel to the recording medium), it is suitable for thinning.

Next, an optical pickup according to a fifth embodiment will be described with reference to FIG. As shown in FIG. 5A, the optical pickup includes a fixed mirror 524 that reflects a light beam emitted from a light source unit (not shown) downward, and a galvano mirror disposed below the fixed mirror 524. 520 and two mirrors 532 and 5
34, and two objective lenses 542 and 544.

The objective lens 542 constitutes one condensing means, and the objective lens 544 constitutes another condensing means.
As shown in FIG. 5B, the rising mirror 532 and the rising mirror 534 are separated in a direction parallel to the surfaces of the recording media 552 and 554, and are separated from the light source unit by the fixed mirror 52.
The light beam 57 is arranged so as to sandwich the light beam 570 toward
0 are opposite to each other and the objective lens 5
42 is located above the rising mirror 532, and the objective lens 544 is located below the rising mirror 534.

As shown in FIG. 5A, the objective lens 542 faces a recording medium 552 disposed above the optical pickup, and the objective lens 544 is disposed below the recording medium 554 disposed below the optical pickup. Confront.

The galvanomirror 520 is swingably supported about a swing shaft 522 as a swing center. Swing shaft 522
Is set parallel to the surfaces of the recording media 552 and 554.

In FIG. 5B, the light beam 570 traveling from the light source unit to the fixed mirror 524 is
After being reflected by the mirror, the light enters the galvanomirror 520. The light beam incident on the galvanometer mirror 520 is fixed to the fixed mirror 524 according to the inclination of the reflection surface of the galvanometer mirror 520.
Is reflected toward the rising mirror 532 via the mirror or the rising mirror 534 via the fixed mirror 524.

Light beam 5 heading to rising mirror 532
72 is reflected by the rising mirror 532 and then condensed by the objective lens 542 to be recorded on the recording medium 552 (FIG. 5).
A light spot is formed on the recording surface of (A). Also,
The light beam 574 traveling to the rising mirror 534 is reflected by the rising mirror 534 and then condensed by the objective lens 544 to form a light spot on the recording surface of the recording medium 554 (see FIG. 5A).

That is, the light beam 570 can be changed by greatly changing the inclination of the reflecting surface of the galvanometer mirror 520.
It is selectively guided to either the objective lens 542 facing the recording medium 552 located above the optical pickup or the objective lens 544 facing the recording medium 554 located below the optical pickup.

The tracking control is performed by the galvanometer mirror 52.
This is performed by swinging 0 in a minute range and changing the inclination of the reflection surface. For example, the incident angle of the light beam 572 toward the objective lens 532 with respect to the objective lens 542 changes according to a slight change in the inclination of the reflection surface of the galvanomirror 520, and as a result, is formed on the recording surface of the recording medium 552. The light spot moves along the tracking direction indicated by the arrow in the figure. The same applies to the light beam 574 heading for the objective lens 544.

As described above, in this optical pickup,
A galvanomirror 52 is driven by a driving mechanism (not shown).
The recording medium to be irradiated with the light beam is switched by greatly changing the inclination of the reflection surface of 0, and tracking control is performed by controlling the inclination of the reflection surface of the galvanomirror 520 in a narrow range.

The galvanomirror 520 has an objective lens 542.
And 544, the optical path length from the galvanometer mirror 520 to the objective lenses 542 and 544 is relatively short. For this reason, even if the inclination of the reflecting surface of the galvanometer mirror 520 is changed relatively large, the objective lens 542
And the shift of the light beam incident on 544 is small. As a result, the light spot formed on the recording medium can be moved relatively large.

The light reflected by the recording medium returns in the direction of the incident optical path, and finally enters a detector for detecting the return light beam. The detector generates information necessary for information reproduction, tracking control, and the like based on the return light beam.

As can be seen from the above description, this optical pickup switches the objective lens on which the light beam enters by largely changing the inclination of the reflection surface of the galvanometer mirror 520, and changes the reflection surface of the galvanometer mirror 520. Tracking control is performed by controlling the inclination by changing it in a narrow range.

In this optical pickup, the swing shaft 522 supporting the galvanomirror 520 is connected to the recording medium 552.
And 554 extend parallel to the plane and the galvanomirror 520
Are also arranged in parallel with the surfaces of the recording media 552 and 554, so that the height dimension of the housing 560 accommodating the same can be made relatively small.

Even if a galvano mirror 520 having a long pair of spring portions 720 as shown in FIG. 7, that is, a galvano mirror long in the direction of the swing axis, can be used as a thin device. Further, since the spring portion of the galvanomirror can be lengthened, the stress generated in the spring portion can be reduced, and a highly reliable galvanomirror can be used.

Finally, an optical pickup according to a sixth embodiment will be described with reference to FIG. As shown in FIG. 6A, the optical pickup includes a galvano mirror 620 for deflecting a light beam emitted from the light source unit, two rising mirrors 632 and 634, and two objective lenses 642.
And 644.

The objective lens 642 constitutes one condenser means, and the objective lens 644 constitutes another condenser means.
The rising mirror 632 and the rising mirror 634 are separated in a direction orthogonal to the surfaces of the recording media 652 and 654,
Light beam 67 traveling from the light source unit to the galvanometer mirror 620
The light beams 670 are located on opposite sides of each other so as to sandwich 0.

In the first to fifth embodiments, the direction from the light source to the galvanometer mirror is a direction substantially orthogonal to the tracking direction, but in the present embodiment, the direction to the galvanometer mirror is a direction parallel to the tracking direction. .

The objective lens 642 is a rising mirror 632
, And the objective lens 644 is located on the rising mirror 6.
34. The objective lens 642 faces the recording medium 652 disposed above the optical pickup, and the objective lens 644 faces the recording medium 654 disposed below the optical pickup.

The galvanomirror 620 is swingably supported about a swing shaft 622 as a swing center. Swing shaft 622
Extends parallel to the planes of the recording media 652 and 654.
The light beam 670 incident on the galvanomirror 620 is changed by the galvanomirror 620 according to the inclination of the reflection surface thereof to the rising mirror 632 or the rising mirror 634.
Oriented to. The light beam 672 reflected by the rising mirror 632 is collected by the objective lens 642,
A light spot is formed on the recording surface of the recording medium 652. Also, the light beam 674 reflected by the rising mirror 634
Is condensed by the objective lens 644, and the recording medium 654
To form a light spot on the recording surface.

That is, the light beam 670 changes the inclination of the reflection surface of the galvanometer mirror 620 greatly,
It is selectively guided to either the objective lens 642 facing the recording medium 652 located above the optical pickup or the objective lens 644 facing the recording medium 654 located below the optical pickup. That is, the light beam 6
In 70, the incident objective lens is switched by largely changing the inclination of the reflection surface of the galvanometer mirror 620.

The light spot formed on the recording medium is moved in a direction crossing a track formed on the recording medium, that is, in a tracking direction by changing the inclination of the reflection surface of the galvanometer mirror 620 in a narrow range. You. That is, tracking control is performed by shaking the reflecting surface of the galvanometer mirror 620 in a narrow range.

The galvanomirror 620 has an objective lens 642
And 644, the optical path length from the galvanomirror 620 to the objective lenses 642 and 644 is relatively short. Therefore, even if the inclination of the reflecting surface of the galvanometer mirror 620 is changed relatively large, the objective lens 642
And the shift of the light beam incident on 644 is small. As a result, the light spot formed on the recording medium can be moved relatively large.

The light reflected by the recording medium returns in the reverse direction of the incident optical path, and finally enters a detector for detecting the return light beam. The detector generates information necessary for information reproduction, tracking control, and the like based on the return light beam.

As can be understood from the above description, in this optical pickup, the objective lens on which the light beam is incident is switched by greatly changing the inclination of the reflection surface of the galvanometer mirror 620, and the inclination of the reflection surface of the galvanometer mirror 620 is changed. Tracking control is performed by controlling in a narrow range.

In this embodiment, the direction from the light source to the galvanometer mirror is parallel to the tracking direction. Therefore, the so-called separation optical system in which the light source is fixed and only the galvanometer mirror, the rising mirror, and the objective lens are accessed and driven is used. Thus, the mass of the access drive can be reduced.

FIG. 6B shows a modification of this optical pickup.
Shown in In the optical pickup of the modified example, the galvanomirror 620 is arranged so that its reflection surface is substantially parallel to the surfaces of the recording media 652 and 654, and the optical beam 670 emitted from the light source unit is applied to the galvanomirror 620. A fixed mirror 624 is further provided that reflects the light beam of the galvanometer mirror 620 toward the rising mirrors 632 and 634 while reflecting the light beam toward the rising mirror 632 and 634.

The optical pickup shown in FIG.
Compared with the optical pickup of (A), there is a slight difference in structure, but the function is completely the same. The present invention is not limited to the above-described embodiment at all, and includes all implementations without departing from the gist of the invention.

In the embodiment, the optical pickup provided with the two objective lenses for converging the light beams on different recording media arranged vertically is described. The direction is set to the same direction as the rising mirror 132, and the light beam reflected by the rising mirror 132 is applied to the recording medium 1 via the objective lens 144.
The present invention may be applied to an optical pickup having two objective lenses for converging a light beam on a recording medium disposed on one side by making a configuration such that the light beam is directed toward the recording medium. . Examples of such an optical pickup include an optical pickup having an objective lens with a high NA and an objective lens with a low NA, for example, an optical pickup having an objective lens for a CD and an objective lens for a DVD.

The present invention can be applied to any optical pickup for optically recording and reproducing information, and the type is not limited. For example, the present invention can be applied to an optical pickup for a read-only optical disk and an optical pickup for a recordable magneto-optical disk. Further, the present invention can also be applied to an optical pickup using a near-field recording technique, which has recently attracted attention.

This specification includes the inventions described in the following sections. 1. A light source unit that emits a light beam, two light collecting units that collect the light beam on a recording medium, and a galvanometer mirror that directs the light beam from the light source unit to one of the two light collecting units. The galvanomirror is located near two condensing means, and the light beam is selectively directed to one of the two condensing means by largely shaking the reflection surface of the galvanomirror. Optical pickup that performs tracking control by swinging the reflecting surface of a galvanometer mirror in a narrow range.

2. In the first aspect, each condensing means includes an objective lens arranged to face the recording medium and a rising mirror for deflecting the light beam from the galvanometer mirror toward the objective lens. An optical pickup that is separated in a direction parallel to a surface of a recording medium, and a light beam emitted from a light source unit passes between two rising mirrors and reaches a galvano mirror.

3. In the first aspect, one of the light condensing means includes an objective lens disposed to face the recording medium, and the other light condensing means transmits the light beam from the objective lens and the galvanomirror disposed to face the recording medium. An optical pickup comprising a rising mirror that deflects toward an objective lens.

4. 2. The optical pickup according to claim 1, wherein the condensing means is located between the galvanomirror and the light source. 5. 2. The optical pickup according to claim 1, wherein the light from the light source unit is reflected by the galvanomirror and enters the condensing unit via the mirror.

6. In the first aspect, each condensing means comprises an objective lens arranged to face the recording medium and a rising mirror for deflecting a light beam from the galvanometer mirror toward the objective lens, and the two rising mirrors are An optical pickup which is arranged side by side in a direction parallel to a surface of the recording medium, and the light beam emitted from the light source passes through the optical pickup and reaches the galvanomirror.

7. In the first aspect, each condensing means comprises an objective lens arranged to face the recording medium and a rising mirror for deflecting a light beam from the galvanometer mirror toward the objective lens, and the two rising mirrors are An optical pickup which is arranged side by side in a direction parallel to a surface of the recording medium, and in which the light beam emitted from the light source unit passes through and reaches the galvanomirror.

8. 2. The optical pickup according to claim 1, wherein a swing axis of the galvanomirror is parallel to a surface of the recording medium. 9. 9. The optical pickup according to claim 8, wherein light from the light source unit enters the galvanometer mirror via a fixed mirror.

[0111]

According to the present invention, it is possible to obtain an optical pickup capable of performing both switching of the direction of a light beam and tracking control with one galvanometer mirror.

[Brief description of the drawings]

FIG. 1 schematically shows an optical pickup according to a first embodiment of the present invention, in which (A) is a plan view and (B) is a side view.

FIGS. 2A and 2B schematically show a main part of an optical pickup according to a second embodiment of the present invention, and FIG.
(B) is a side view thereof.

FIG. 3 schematically shows a main part of an optical pickup according to a third embodiment of the present invention, and FIG.
(B) is a front view of this as viewed from the light source unit side.

4A and 4B schematically show an optical pickup according to a fourth embodiment of the present invention, wherein FIG. 4A is a plan view thereof, and FIG. 4B is a perspective view of a main part thereof.

FIG. 5 schematically shows a main part of an optical pickup according to a fifth embodiment of the present invention, and FIG.
(B) is a perspective view thereof.

FIG. 6 schematically shows an optical pickup according to a sixth embodiment of the present invention, wherein (A) is a side view of a main part thereof,
(B) is a side view of the modification.

7A and 7B show a galvanomirror used in the optical pickup of the present invention, and FIG.
(B) is a BB sectional view thereof.

[Explanation of symbols]

 110 light source / detection unit 120 galvanometer mirror 132 rising mirror 134 rising mirror 142 objective lens 144 objective lens

Claims (3)

[Claims] A light source for emitting a light beam; two light condensing means for condensing the light beam on a recording medium; and a galvanometer for directing the light beam from the light source to one of the two light condensing means. A mirror, wherein the galvanomirror is located near two light-gathering means, and the reflecting surface of the galvanomirror is largely shaken to cause the light beam to be emitted from one of the two light-gathering means. An optical pickup that performs tracking control by selectively orienting the mirror and shaking the reflecting surface of the galvanometer mirror in a narrow range. 2. The apparatus according to claim 1, wherein each condensing means comprises an objective lens arranged to face the recording medium and a rising mirror for deflecting a light beam from the galvanometer mirror toward the objective lens. An optical pickup in which a rising mirror is separated in a direction parallel to a surface of a recording medium, and a light beam emitted from a light source unit passes between two rising mirrors and reaches a galvano mirror. 3. The apparatus according to claim 1, wherein one of the light-collecting means comprises an objective lens arranged opposite to the recording medium, and the other light-collecting means comprises an objective lens arranged opposite to the recording medium and a galvanomirror. An optical pickup comprising a rising mirror that deflects the light beam from the lens toward the objective lens.