JP2000132860A - Optical pickup - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical pickup which is capable of detecting the absolute rotational position and the rotational extent (rotational angle) of a deflection optical device with a simple constitution and which is low in cost, small in size and light in weight. SOLUTION: This optical pickup is provided with an optical head 6 converging laser beams from a laser beam source 2 on a recording medium 4, a deflection optical device 8 capable of scanning the laser beams being converged on the recording medium 4 along the recording medium 4 with the optical head 6 by deflecting the laser beams from the laser beam source 2 and a detecting sensor 10 capable of optically detecting the rotational position and the rotational extent of the deflection optical device, 8, and the device 8 is composed of a beam splitter capable of reflecting a part of the laser beams from the source 2 toward the detecting sensor 10 and also capable of transmitting remaining laser beams toward the optical head 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical pickup for performing optical recording or optical reproduction of information on a recording medium.

[0002]

2. Description of the Related Art Conventionally, this type of optical pickup generally uses a deflecting optical element in order to perform fine movement tracking control on a recording medium when recording and reproducing information.

As a first prior art, for example, Japanese Patent Laid-Open No.
In the device disclosed in Japanese Patent No. 318331, a galvanomirror is used as a deflection optical element. In this device, first,
An optical axis shift amount between the optical axis of the optical system and the center of the light beam is measured based on a track shift signal obtained when the galvanomirror is rotated. Subsequently, a correction amount is obtained based on the optical axis shift amount. Then, by rotating the galvanometer mirror according to the correction amount, the optical axis deviation is eliminated, and accurate tracking control is performed (first conventional technique).

[0004] As a second prior art, a beam splitter is added in the optical path of an optical system, and a part of the light beam is guided to a position detecting sensor via the beam splitter, thereby providing a deflection optical element. There is also known a method of detecting an absolute rotation position and a rotation amount (rotation angle).

Further, as a third prior art, for example, Japanese Patent Laid-Open No. 5-28523 discloses the following two methods. In one of the methods, a separately prepared light source is fixed to a mirror holder, and a light beam from the light source is detected, thereby detecting the amount of tilt of the mirror. In another method, when the back surface of the mirror is used as a reflection surface, and a light source provided separately irradiates the back surface of the mirror with a light beam,
By detecting the light reflected from the back surface of the mirror, the amount of tilt of the mirror is detected. As an example to which a similar method is applied, for example, Japanese Patent Application Laid-Open No. 5-334703 discloses a method of detecting a mirror tilt amount using a photo reflector in which a light emitting element and a light receiving element are integrated. .

[0006]

However, each of the first to third prior arts described above has the following problems. In the first prior art, since the absolute rotation position and the rotation amount (rotation angle) of the galvanomirror cannot be detected, the galvanomirror once pivots greatly and the track error signal cannot be detected. Then,
It becomes difficult to perform accurate tracking control.

In the second prior art, since a beam splitter must be separately prepared, not only the manufacturing cost of the apparatus is increased, but also the apparatus is increased in size and weight.

In the third prior art, since a light source and a light emitting element must be separately prepared, the manufacturing cost of the device increases. The present invention has been made to solve such a problem, and an object of the present invention is to detect an absolute rotation position and a rotation amount (rotation angle) of a deflection optical element with a simple configuration. It is an object of the present invention to provide a small and lightweight optical pickup at a very low price.

[0009]

In order to achieve the above object, an optical pickup according to the present invention comprises a laser light source, an optical head for condensing laser light emitted from the laser light source on a recording medium, and A deflecting optical element capable of scanning laser light converged on a recording medium via an optical head by deflecting laser light emitted from a laser light source along the recording medium, and the deflecting optical element And a detection sensor capable of optically detecting the rotation position and the rotation amount of the deflection optical element, and the deflection optical element can reflect part of the laser light emitted from the laser light source toward the detection sensor, The beam splitter is configured to transmit the remaining laser light toward the optical head. Further, the optical pickup of the present invention comprises a laser light source, an optical head for condensing the laser light emitted from the laser light source on a recording medium, and an optical head by deflecting the laser light emitted from the laser light source. A deflecting optical element capable of scanning laser light converged on the recording medium through the recording medium via the recording medium, and a detection sensor capable of optically detecting a turning position and a turning amount of the deflecting optical element. The deflection optical element is composed of a beam splitter that can transmit a part of the laser light emitted from the laser light source toward the detection sensor and reflect the remaining laser light toward the optical head. Have been.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an optical pickup according to a first embodiment of the present invention will be described with reference to FIG. As shown in FIG. 1A, an optical pickup according to the present embodiment includes a laser light source 2, an optical head 6 for condensing laser light emitted from the laser light source 2 on a recording medium 4, a laser light source 2 A deflecting optical element 8 capable of scanning along the recording medium 4 the laser light focused on the recording medium 4 via the optical head 6 by deflecting the laser light emitted from the A detection sensor 10 capable of optically detecting the rotation position and the rotation amount (rotation angle) of the optical element 8 is provided.

The optical head 6 includes a reflection mirror 12 and an objective lens 14 for condensing the light reflected from the reflection mirror 12 on the recording medium 4. In the present embodiment, the optical head 6 is configured to move linearly in parallel along the radial direction of the recording medium 4, or the optical head 6 is mounted on a swing arm (not shown), A configuration may be adopted in which the recording medium 6 swings in a curved shape along a direction transverse to the radial direction of the recording medium 4.

As the detection sensor 10, a non-split type or two-segment type light receiving element such as a photodiode can be appropriately selected and used.
Is configured such that the turning position and the turning amount (turning angle) of the deflecting optical element 8 can be optically detected based on the light receiving position and the light receiving amount of the light reflected from the deflecting optical element 8. ing.

The deflecting optical element 8 is capable of reflecting part of the laser light L emitted from the laser light source 2 toward the detection sensor 10 and transmitting the remaining laser light toward the optical head 6. It is composed of a beam splitter having a mirror surface 8a (for example, a half mirror prism).

As a rotating mechanism for rotating the deflecting optical element 8, the present embodiment includes a holder 16 for holding the deflecting optical element 8, as shown in FIGS. A drive coil 18 disposed on the outer periphery of the drive coil 16 and a permanent magnet 20 disposed opposite to the drive coil 18 are provided. The holder 16 is rotatably attached to a fixed member 24 by an elastic member 22.
0 is fixed to the fixing member 24. The detection sensor 10 is fixed to a fixing member 24 (FIG. 1B).
reference).

According to such a rotating mechanism, a predetermined electric current is applied to the driving coil 18 to generate a magnetic force between the driving coil 18 and the permanent magnet 20, so that the deflecting optics together with the holder 16 are provided. The element 8 can be rotated by a predetermined amount in the direction of arrow R. At this time, the deflection optical element 8
The reflected light L1 reflected from the half mirror surface 8a changes the light receiving position and the light receiving amount with respect to the detection sensor 10 according to the amount of rotation of the deflection optical element 8. The detection sensor 10 detects the turning position and the turning amount (turning angle) of the deflecting optical element 8 based on the change in the light receiving position and the light receiving amount of the reflected light L1. On the other hand, the transmitted light L2 transmitted through the half mirror surface 8a of the deflecting optical element 8 depends on the amount of rotation of the deflecting optical element 8,
The direction is deflected in the direction of arrow D (see FIG. 1B).

Next, the operation of this embodiment will be described. The laser light L emitted from the laser light source 2 is converted into a parallel light beam by the collimator lens 26, and then enters the half mirror surface 8a of the deflection optical element 8. The laser light L incident on the half mirror surface 8a is irradiated on the detection sensor 10 after a part (about 3%) of the laser light L is reflected from the half mirror surface 8a. At this time, the detection sensor 10
Detects optically the turning position and the turning amount (turning angle) of the deflecting optical element 8 based on the light receiving amount and the light receiving position of the reflected light L1.

On the other hand, the transmitted light L2 transmitted through the half mirror surface 8a is guided to the optical head 6 while maintaining a parallel light flux. The transmitted light L2 guided to the optical head 6 is reflected from the reflection mirror 12, and then collected on the recording medium 4 by the objective lens. At this time, the coarse head tracking control for the recording medium 4 is performed by moving the optical head 6 along the recording medium 4 (linear movement, swinging), and the deflection optical element 8 is finely rotated in a predetermined direction. By doing so, the fine movement tracking control for the recording medium 4 is performed. Then, optical recording or optical reproduction of information on the recording medium 4 is performed while performing such coarse movement and fine movement tracking control.

In this case, the return light reflected from the recording medium 4 travels back on the same optical path again, and is irradiated to a light detection unit (not shown). Is detected.

According to the present embodiment, a beam splitter is applied as the deflecting optical element 8 and its half mirror surface 8
In addition to the configuration in which the turning position and the turning amount (turning angle) of the deflecting optical element 8 are detected using the reflected light L1 from a, a turning mechanism for turning the deflecting optical element 8 is further provided. On the other hand, by arranging the detection sensor 10 integrally, it is possible to realize a low-cost, small-size and low-weight optical pickup without largely changing the configuration of the existing optical pickup.

Further, according to the present embodiment, since the optical systems of the optical pickup can be arranged almost in series, especially in an optical pickup of a type in which all optical components are mounted on a swing arm, the inertia force and the The effect that resonance and the like can be suppressed can be obtained.

The present invention is not limited to the configuration of the above-described embodiment, but can be variously modified as follows. For example, as shown in FIG. 2, a hemispherical lens (for example, SIL (solid immersion lens)) 28 for near-field recording and a magnetic coil 30 are added to the optical head 6, and the converged light from the objective lens 14 is converted into a hemispherical lens. 2
8 further reduces the spot diameter of the laser light focused on the recording medium 4 and records the optical head 6 by aerodynamic lift acting between the rotated recording medium 4 and the optical head 6. You may comprise so that it may float slightly from the medium 4. FIG. By combining such techniques, the spot diameter of the laser beam can be further reduced without performing focus control, and the recording density on the recording medium 4 can be improved. When such an optical head 6 for near-field recording is configured, the objective lens 14,
It is preferable to hold the hemispherical lens 28 and the magnetic coil 30.

As shown in FIG. 3, for example, a first relay lens 32 is arranged in the optical path between the collimating lens 26 and the half mirror surface 8a of the deflecting optical element 8, and the deflecting optical element 8 Even if the second relay lens 34 is arranged in the optical path between the head 6 and the second relay lens 34, the same operation and effect as the above-described embodiment can be realized.

In this case, the laser light L from the laser light source 2 is collimated by the collimator lens 26, then converged by the first relay lens 32, and enters the half mirror surface 8a of the deflecting optical element 8. After a part (about 3%) of the laser light L incident on the half mirror surface 8a is reflected from the half mirror surface 8a,
The light is emitted to the detection sensor 10. On the other hand, half mirror surface 8
The transmitted light L2 that has passed through a is focused again at the focal point F, diverges again, is irradiated on the second relay lens 34, is converted into a parallel light beam by the second relay lens, and is guided to the optical head 6.

Next, an optical pickup according to a second embodiment of the present invention will be described with reference to FIG. In the description of the present embodiment, the same components as those of the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

In the first embodiment, the turning position and the turning amount (turning amount) of the deflecting optical element 8 are determined based on the optical characteristics of a part of the laser light reflected from the half mirror surface 8a of the deflecting optical element 8. In this embodiment, the rotation position and rotation of the deflecting optical element 8 are determined based on the optical characteristics of a part of the laser light transmitted through the half mirror surface 8a of the deflecting optical element 8. The amount of movement (rotation angle) is detected.

For this reason, as shown in FIG. 4A, the deflection optical element 8 applied to the present embodiment is
A beam splitter (for example, a half mirror) having a half mirror surface 8a capable of transmitting a part of the laser light L emitted from the optical head 6 and reflecting the remaining laser light toward the optical head 6 prism)
It is composed of

As a rotating mechanism for rotating the deflecting optical element 8, in the present embodiment, as shown in FIG. 4B, a holder 36 for holding the deflecting optical element 8, and insert molding to this holder 36 A driving coil 38 is provided, and a permanent magnet 40 is disposed opposite to the driving coil 38. The holder 36 is rotatably attached to the fixed member 42 by an elastic member (not shown), and the permanent magnet 40 is fixed to the fixed member 42. The detection sensor 10 is fixed to a fixing member 42.

According to such a rotating mechanism, a predetermined current is caused to flow through the driving coil 38 to generate a magnetic force between the driving coil 38 and the permanent magnet 40, so that the deflecting optical system together with the holder 36 is provided. The element 8 can be rotated by a predetermined amount in the direction of arrow R. At this time, the deflection optical element 8
Of the transmitted light L1 transmitted through the half mirror surface 8a, the light receiving position and the light receiving amount with respect to the detection sensor 10 change according to the amount of rotation of the deflection optical element 8. The detection sensor 10 detects the rotation position and the rotation amount (rotation angle) of the deflecting optical element 8 based on changes in the light reception position and the light reception amount of the transmitted light L1. On the other hand, the direction of the reflected light L2 reflected from the half mirror surface 8a of the deflecting optical element 8 is deflected in the direction of arrow D according to the amount of rotation of the deflecting optical element 8.

The other configuration is the same as that of the optical pickup shown in FIG. 3, and the description is omitted.
Next, the operation of the present embodiment will be described.

The laser light L from the laser light source 2 is collimated by the collimator lens 26,
Converged by the relay lens 32 of the deflecting optical element 8
To the half mirror surface 8a. After a part (about 3%) of the laser beam L incident on the half mirror surface 8a passes through the half mirror surface 8a, the detection sensor 1
It is irradiated to 0. At this time, the detection sensor 10 optically detects the turning position and the turning amount (turning angle) of the deflecting optical element 8 based on the light receiving amount and the light receiving position of the transmitted light L1.

On the other hand, the reflected light L2 reflected from the half mirror surface 8a diverges again after forming the focal point F and irradiates the second relay lens 34.
, And is guided to the optical head 6.

The reflected light L2 guided to the optical head 6 is
After being reflected from the reflection mirror 12, the light is focused on the recording medium 4 by the objective lens 14. At this time, the coarse head tracking control for the recording medium 4 is performed by moving the optical head 6 along the recording medium 4 (linear movement, swinging), and the deflection optical element 8 is finely rotated in a predetermined direction. By doing so, the fine movement tracking control for the recording medium 4 is performed. Then, optical recording or optical reproduction of information on the recording medium 4 is performed while performing such coarse movement and fine movement tracking control.

In this case, the return light reflected from the recording medium 4 travels back on the same optical path again, and is irradiated to a light detection unit (not shown). Is detected.

According to the present embodiment, a beam splitter is applied as the deflecting optical element 8 and its half mirror surface 8
a, the rotation position and the rotation amount (rotation angle) of the deflecting optical element 8 are detected by using the transmitted light L1 that has passed through the optical element L. By arranging the detection sensor 10 integrally, a low-cost, small-sized and low-weight optical pickup can be realized without largely changing the configuration of the existing optical pickup.

Further, according to the present embodiment, since the optical systems of the optical pickup can be arranged almost in series, especially in an optical pickup in which all optical components are mounted on a swing arm, the inertia force and the The effect that resonance and the like can be suppressed can be obtained.

The present invention is not limited to the configuration of the above-described embodiment, and can be variously modified as follows. For example, as shown in FIG. 4C, even when a parallel plate-shaped half mirror 8 ′ is applied as the deflecting optical element 8, the same operation and effect as the above-described embodiment can be realized. The half mirror 8 ′ of the present modification has a laser beam L emitted from the laser light source 2.
Is provided with a half mirror surface 8a 'that can transmit a part of the laser beam toward the detection sensor 10 and can reflect the remaining laser beam toward the optical head 6.

According to this modification, since the deflecting optical element is constituted by the parallel plate-shaped half mirror 8 ', the processing of the deflecting optical element becomes easy and the manufacturing cost can be reduced. As a result, it is possible to realize a lower-priced optical pickup. Note that the other effects are the same as those of the above-described embodiment, and the description thereof is omitted.

Also in this embodiment, similarly to the first embodiment (see FIG. 2), a hemispherical lens for near-field recording (for example, SIL (solid immersion lens)).
The optical head 6 may be configured by additionally providing the magnetic head 30 and the magnetic coil 30.

[0039]

According to the present invention, a beam splitter is applied as a deflection optical element, and the rotation position and the rotation amount (rotation angle) of the deflection optical element are detected using light from the half mirror surface. With such a configuration, it is possible to provide an inexpensive, small-sized and low-weight optical pickup.

[Brief description of the drawings]

FIG. 1A is a diagram illustrating a configuration of an optical pickup according to a first embodiment of the present invention, and FIG. 1B is a longitudinal sectional view illustrating a configuration of a rotation mechanism that rotates a deflection optical element. , (C)
FIG. 5 is a front view showing the configuration of a rotation mechanism for rotating the deflection optical element, as viewed from the optical head side.

FIG. 2 is a diagram showing a configuration of an optical head for near-field recording.

FIG. 3 is a diagram showing a configuration of an optical pickup according to a modification of the first embodiment.

FIG. 4A is a diagram illustrating a configuration of an optical pickup according to a second embodiment of the present invention, and FIG. 4B is a longitudinal sectional view illustrating a configuration of a rotation mechanism that rotates a deflection optical element. , (C)
FIG. 9 is a longitudinal sectional view showing a configuration of a turning mechanism for turning a deflection optical element according to a modification of the present invention.

[Explanation of symbols]

 2 laser light source 4 recording medium 6 optical head 8 deflection optical element 10 detection sensor

Claims (3)

[Claims] A laser light source; an optical head for condensing the laser light emitted from the laser light source on a recording medium; and a recording medium via the optical head by deflecting the laser light emitted from the laser light source. A deflecting optical element capable of scanning the laser beam converged on the recording medium along the recording medium, and a detection sensor capable of optically detecting the turning position and the amount of turning of the deflecting optical element. The deflection optical element can reflect a part of the laser light emitted from the laser light source toward the detection sensor,
An optical pickup comprising a beam splitter capable of transmitting the remaining laser light toward an optical head. 2. A laser light source; an optical head for condensing laser light emitted from the laser light source on a recording medium; and a recording medium via the optical head by deflecting the laser light emitted from the laser light source. A deflecting optical element capable of scanning the laser beam converged on the recording medium along the recording medium, and a detection sensor capable of optically detecting the turning position and the amount of turning of the deflecting optical element. The deflecting optical element can transmit part of the laser light emitted from the laser light source toward the detection sensor,
An optical pickup comprising a beam splitter capable of reflecting the remaining laser light toward an optical head. 3. The optical pickup according to claim 1, wherein the deflection optical element is a half mirror prism.