WO2007086171A1

WO2007086171A1 - Optical pickup and information processing device

Info

Publication number: WO2007086171A1
Application number: PCT/JP2006/321032
Authority: WO
Inventors: Hiroaki Kojima; Kanji Wakabayashi; Kouretsu Boku
Original assignee: Matsushita Electric Industrial Co., Ltd.
Priority date: 2006-01-27
Filing date: 2006-10-23
Publication date: 2007-08-02
Also published as: TW200739565A; JP2007200462A

Abstract

Displacement of an optical axis occurring in light beam transmission regulation means for regulating optical power of a light beam is reduced by a simple mechanism. The optical pickup has a holding body for holding a first transmission element and a second transmission element that cross each other perpendicularly and having a permanent magnet fixed to the holding body, and also has a base for holding a rotating shaft and having mounted on it a core and a coil that switch over the holding body between first and second switchover positions or hold the holding body at the switchover positions. At the first switchover position where the light beam passes through the first transmission element, the permanent magnet and the core are attracted and held by each other in an attitude where a small projection of the holding body is in contact with a regulation surface of the base. At the second switchover position where the light beam passes through the second transmission element, the permanent magnet and the core are attracted and held by each other and positioned in an attitude where the small projection of the holder in contact with the regulation surface of the base. The holding body is switched over between the first and second switchover positions by applying a pulse to the coil.

Description

Specification

Optical pickup and information processing apparatus

Technical field

[0001] The present invention relates to an optical pickup and an information processing apparatus.

Background art

[0002] A DVD (digital versatile disc) can record digital data at a recording density about 6 times that of a CD (Compact Disc Interactive), and writes large volumes of digital data such as movies and music. It is known as an information recording medium (optical disc). In recent years, since the amount of information to be recorded has increased, an information recording medium having a larger capacity has been demanded.

[0003] In order to increase the capacity of an information recording medium such as an optical disc, it is necessary to increase the information recording density. This is generally realized by reducing the spot diameter of the laser beam emitted to the optical disc when writing and reading data. In order to reduce the spot diameter of the light, it is only necessary to shorten the wavelength of the laser light and increase the numerical aperture (NA) of the objective lens. Furthermore, for example, by using a blue laser beam having a wavelength of 405 nm and an objective lens having an NA of 0.85, information can be recorded at a recording density five times that of the current DVD.

[0004] In addition to shortening the wavelength of laser light by using a blue laser or the like, in order to further increase the recording density, development of a technique for providing a plurality of recording layers on one optical disk is also progressing. For example, if it becomes possible to obtain an optical disc having two recording layers, the DVD has a recording layer with a recording density of one layer in combination with the above-mentioned shortening of the laser beam wavelength and the use of an objective lens having a large NA. About 10 times.

However, in an optical disc apparatus using a blue laser as a light source, the margin of light power for reproduction in the blue laser is extremely small, so that quantum noise of the light source becomes a problem.

[0006] In view of this, the optical disc apparatus disclosed in Japanese Patent Application Laid-Open No. 2000-195086 discloses an optical pickup provided with a light beam transmission adjusting means (intensity filter) that can be taken in and out substantially perpendicularly to the laser beam path. In this optical disc apparatus, the intensity filter is inserted into the laser beam path during reproduction, and the intensity filter is moved so as to remove the path force of the emitted light during recording. Thereby, for example, the quantum noise of the semiconductor laser can be kept low, and high quality reproduction is possible.

However, since this optical disk apparatus is provided with an intensity filter that can be taken in and out perpendicularly to the laser beam path, a space for moving the intensity filter is required. As a result, an optical pickup is required. There exists a problem that an apparatus will enlarge.

In order to solve such a problem, the following optical pickup device provided with an intensity filter that moves on the optical axis by rotation instead of the intensity filter that moves linearly on the optical axis is considered. It is done. The optical pickup will be described below with reference to FIGS. 5 to 7A and 7B.

FIG. 5 shows a configuration of a conventional optical pickup device. When the GaN-based semiconductor laser light source 30 emitting blue light emits a blue light beam, the light beam enters the light beam transmission adjusting means 31. The light beam transmission adjusting means 31 is rotated to a predetermined position according to whether data is read from the optical disk 32, and the position of the intensity filter is adjusted. The light beam that has passed through the light beam transmission adjusting means 31 is reflected by the beam splitter 33, converted into parallel light by the collimating lens 34, reflected by the mirror 35, transmitted through the objective lens 36, and condensed on the optical disk 32. The

At the time of reading data, the collected light beam is reflected by the recording layer of the optical disc 32, reaches the beam splitter 33 through the reverse path, passes through the beam splitter 33, passes through the multilens 37, and is a photodiode. Incident on 38. The photodiode 38 is a so-called photodetector, and outputs an electrical signal based on the position and intensity of incident light. Based on the electrical signal, data is reproduced.

On the other hand, when data is written, an optical spot is formed on the information layer by the condensed light beam. As a result, the state of the recording layer where the light spot is formed (for example, the crystalline state) changes according to the data to be written. As a result, data is written on the optical disc 32 as a change in the state of the recording layer.

FIG. 6A is a perspective view when the light beam passes through the optical filter of the light beam transmission adjusting unit 31 and corresponds to the arrangement at the time of data reading. Figure 6B shows that the light beam is a light beam. FIG. 6 is a perspective view when the optical filter of the transmission adjustment means 31 does not pass through, and corresponds to the arrangement at the time of data writing. The light beam transmission adjusting means 31 has a first transmissive element 1 and a second transmissive element. The first transmissive element 2 is coated with an optical filter 2a having a transmittance of 50%, and attenuates the optical power of the transmitted light beam. On the other hand, the first transmission element 1 is not coated with an optical filter, and transmits the light beam 39 while maintaining the optical power of the light beam. The light beam transmission adjusting means 31 includes a support means 40 for supporting the first transmissive element 1 and the second transmissive element 2, and the first transmissive element 1 and the second transmissive element 2 on the rotating shaft 12. Rotation drive means 41 for rotating around is included. The rotation axis 12 is parallel to the first transmission element 1 and the second transmission element 2. The light beam transmission adjusting means 31 performs rotation driving around the rotation axis 12 using the rotation driving means 41, whereby the light beam 39 is transmitted through the first transmission element 1 (FIG. 6B), The key (FIG. 6A) that transmits the second transmissive element 2 can be switched. That is, it is possible to switch whether or not the light beam 39 is transmitted through the optical filter 2a. The light power when the light beam 39 is transmitted through the optical filter 2a is 50% of the light power when it is not transmitted.

Disclosure of the invention

Problems to be solved by the invention

[0014] However, if the support means 40 of the light beam transmission adjusting means 31 is rotated to switch the first and second transmission elements 1 and 2, miniaturization can be realized, while light can be reduced. There is another problem that the component accuracy and assembly accuracy of the beam transmission adjusting means 31 are improved, and the angle deviation during mounting and operation must be reduced.

[0015] This will be specifically described with reference to FIGS. 7A and 7B. FIG. 7A shows the state when there is no deviation of the incident angle of the light beam to the second transmissive element 2. The first and second transmissive elements 1 and 2 each have a thickness t. On the other hand, FIG. 7B shows the state of optical axis deviation when there is a deviation of the incident angle of the light beam to the second transmission element 2.

[0016] As shown in FIG. 7B, when the surface of the second transmissive element 2 is not perpendicular to the optical axis (when an incident angle shift occurs), the light is refracted at the incident surface 2a of the second transmissive element 1. Therefore, the optical axis when the light beam is incident on the transmission element 2 and the optical axis when it is emitted are shifted. According to Figs. 7A and 7B, the transmission distance of the light beam is equal to the thickness t. Therefore, the incident angle deviation h of the light beam occurs. Then, since the transmission distance becomes longer in proportion to the thickness t, an optical axis shift d occurs. Of course, the above is the first

The same applies to one transmission element 1.

When the optical axis deviation d occurs, the position of the return spot on the photodiode 38 when it is reflected by the optical disk 32 and enters the photodiode 38 is shifted. Even if the optical axis of the first transmissive element 1 is d, the photodiode 38 can be adjusted and assembled according to the position of the return spot at that time. If the optical axis deviation of the second transmissive element 2 is dA, the return spot position on the photodiode 38 is shifted due to the difference in optical axis deviation (dA-d).

[0018] Therefore, what actually becomes a problem is the difference (dA-d) in the optical axis misalignment between the first transmissive element 1 and the second transmissive element 2. Further, if the thickness t is small, the optical axis deviations d and dA are small. However, there are limitations in handling and assembly work of the transmissive element to reduce the thickness t. As an example, when the thickness t is 0.3 mm, the allowable difference in the optical axis deviation is h (hA—h) where h is the incident angle deviation of the first transmissive element 1 and hA is the incident angle deviation of the second transmissive element 2. ) <1 °, and considering the reliability, an accuracy of (hA—h) <0.5 ° is required at the beginning of assembly. In order to achieve this angular accuracy, it is required that the parts accuracy of the rotary drive means 41 and the assembly accuracy of the first and second transparent elements 1 and 2 with respect to the support means 40 are required, and it is inexpensive considering mass productivity. It is difficult to provide equipment.

Accordingly, an object of the present invention is to provide an optical pickup that can improve switching angle accuracy with a simple configuration without requiring strict component accuracy and assembly accuracy.

Means for solving the problem

The optical pickup according to claim 1 of the present invention transmits a light source that emits a light beam, a light beam transmission adjusting unit that adjusts a transmission amount of the light beam, and the light beam light beam transmission adjusting unit. In an optical pickup having a light condensing means for condensing the light beam on an information recording medium, the light beam transmission adjusting means includes a first transmission element having a first transmittance and the first transmittance. A second transmissive element having a higher second transmittance, and the first transmissive element and the optical beam driven to rotate about a rotation axis parallel to the second transmissive element are transmitted through the first transmissive element. A rotation drive switching mechanism that switches between one position and a second position that transmits the second transmission element, and the rotation drive switching mechanism is connected to a permanent magnet. It is configured so as to be selectively urged to the switching position between the first position and the second position by the suction force, so that the light beam having the first light power and the light beam having the second light power are selectively output. It is characterized by comprising.

[0021] The optical pickup according to claim 2 of the present invention is the optical pickup according to claim 1, wherein the rotation drive switching mechanism holds the first transmissive element and the second transmissive element. And a holding body provided with a hole parallel to the second transmissive element, a first permanent magnet for generating an attracting force for maintaining the first position, which is respectively attached to the holding body, and the second position. A second permanent magnet that generates an attractive force for engaging with a holding shaft that is passed through the hole of the holding body, and the holding body is rotatable around the holding shaft in a state where the holding body is rotatable. For adsorbing the base for regulating the position of the holding body at the first position or the second position so that the axis is on the center line of the light beam, and the first permanent magnet respectively mounted on the base The first iron core is concentric with the first iron core and gives a repulsive force to the first permanent magnet The second iron core for adsorbing the first coil and the second permanent magnet and the second coil concentric with the second iron core and providing a repulsive force to the second permanent magnet are characterized in that .

[0022] The optical pickup according to claim 3 of the present invention is the optical pickup according to claim 2, wherein the first transmissive element mounting surface on which the first transmissive elements orthogonal to each other are mounted on the holding body, and the first 2 a second transmissive element mounting surface for mounting the transmissive element, a first reference surface that is in parallel with the first transmissive element mounting surface and abuts the base to hold the first position, and the second transmissive element mounted A second reference surface that is in contact with the base to hold the second position parallel to the surface, and the base includes the first reference surface and the second reference surface of the holder. It is characterized in that a reference plane that abuts is formed.

[0023] The optical pickup according to claim 4 of the present invention is the optical pickup according to claim 2, wherein the first permanent magnet has a magnetic field direction orthogonal to the first reference plane and the first transmission element. The second permanent magnet is mounted on the holding body so as to be offset from the center, and the second permanent magnet is held so that the magnetization direction is orthogonal to the second reference plane and the central force of the second transmitting element is offset. The first coil is mounted on the base so that the axis is perpendicular to the reference plane and is opposed to the first permanent magnet at the first position, and the second coil is mounted on the base. The shaft is mounted on the base so that an axis is perpendicular to the reference plane and is opposed to the second permanent magnet at the second position.

The optical pickup according to claim 5 of the present invention is the optical pickup according to claim 3, wherein the first reference surface and the second reference surface of the holding body each have a plane determined by three small projections. In addition, the tip shape of each of the small protrusions is a spherical surface.

[0025] The optical pickup according to claim 6 of the present invention is characterized in that, in claim 1, the light source is a semiconductor laser that emits light in a wavelength region of green power and ultraviolet light.

[0026] The optical pickup according to claim 7 of the present invention is characterized in that, in claim 1, the light source is a semiconductor laser that emits light in a blue wavelength region.

[0027] The information processing device according to claim 8 of the present invention is detected by the optical pickup according to claim 1 and the photodetector further including a photodetector that detects reflected light from the information recording medium. And a signal processing circuit for generating at least one of a reproduction signal and a servo signal based on the reflected light.

[0028] The information processing apparatus according to claim 9 of the present invention is capable of loading a plurality of types of information recording media having different numbers of recording layers according to claim 8, and loaded information An information processing apparatus that reads and Z or writes data by emitting a light beam having a magnitude of optical power corresponding to the number of recording layers to a recording medium, wherein the number of recording layers is one. When a recording medium is loaded, the rotational drive switching mechanism switches to the first position to emit a light beam having the first optical power to the recording layer, and the number of recording layers includes a plurality of information. When a recording medium is loaded, the rotation drive switching mechanism switches to the second position to emit a light beam having the second optical power to one of the recording layers. .

The invention's effect

[0029] According to the present invention, the light beam transmission adjusting means for switching the light power of the light beam by rotationally driving two transmitting elements having different transmittances is arranged between the first position and the second position by the attractive force of a permanent magnet. Since it is configured to be selectively biased to the position switching position, it can improve the switching angle accuracy without requiring strict component accuracy and assembly accuracy with a simple configuration, and also has low power consumption and reliability. High, because of low manufacturing cost, high reliability, optical pickup Can be realized.

Brief Description of Drawings

FIG. 1 is a perspective view of a rotary drive switching mechanism 26 that is a light beam transmission adjusting unit according to the present invention.

FIG. 2 is an exploded view of a rotary drive switching mechanism 26 that is a light beam transmission adjusting means according to the present invention.

FIG. 3A is a side view showing a first switching position where the light beam is transmitted through the first transmission element 1. FIG. 3B is a second switching position where the light beam is transmitted through the second transmission element 2. FIG. 4 is a diagram for explaining a relative angle error with respect to the light beam at the first and second switching positions. FIG. 5 is a configuration diagram of a conventional optical pickup device.

6A is a perspective view when the light beam is transmitted through the optical filter of the light beam transmission adjusting unit 31. FIG. 6B is a perspective view when the light beam is not transmitted through the optical filter of the light beam transmission adjusting unit 31.

[FIG. 7A] A diagram showing a state where there is no deviation of the incident angle of the light beam to the second transmission element 2. [FIG. 7B] Light when there is a deviation of the incident angle of the light beam to the second transmission element 2. Diagram showing shaft misalignment

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to FIGS.

FIG. 1 is a perspective view of a rotation drive switching mechanism 26 which is mounted on an optical pickup according to the present invention and is a light beam transmission adjusting means. FIG. 2 shows an exploded view of the rotary drive switching mechanism 26. FIG. 3A is a side view showing the first switching position where the rotation drive switching mechanism 26 transmits the light beam through the first transmission element 1. FIG. 3B is a side view showing the second switching position where the light beam is transmitted through the second transmissive element 2. The configuration of the rotary drive switching mechanism 26 will be described with reference to FIGS. 1 to 3A and 3B.

[0033] The rotation drive switching mechanism 26 includes a base 3, first and second coils 4 and 5, first and second iron cores 6 and 7, a holding body 8, and first and second Permanent magnets 9 and 10, first and second transmission elements 1 and 2, and a cover 11 are included.

[0034] The base 3 supports a coil holding portion 14 for mounting the first and second iron cores 6 and 7 and the first and second coils 4 and 5, and a holding body 8 that is rotationally driven. Holds the shaft 12 (described later) of the cover 11 The holding body rotating surface 15 in which the hole 13 to be formed is formed, and the holding body regulating surface 16 formed on the side of the holding body rotating surface 15 of the coil holding portion 14 are configured.

The holding body regulating surface 16 is formed in a direction perpendicular to the axial centers of the first and second coils 4 and 5 and the holding body rotating surface 15. If the material of the base 3 is a structure according to the present invention, a resin material can be used because accuracy and strength are not particularly required.

[0036] The first coil 4 and the second coil 5 are connected in series, the first iron core 6 is inserted into the first coil 4, and the second iron core 7 is inserted into the second coil 5, respectively. Each core is bonded and fixed to the coil holding portion 14 of the base 3 in a state in which the core is parallel to the optical axis of the light beam. At this time, the end surfaces 6A and 7A of the first and second iron cores 6 and 7 whose core length L2 is slightly larger than the coil length L1 are fixed in close contact with the end surface 17 on the holding body regulating surface 16 side. Yes.

The holding body 8 is formed with a first surface 18 and a second surface 19 that are orthogonal to each other. The first transmissive element 1 is bonded and fixed to the first surface 18. The second transmissive element 2 is bonded and fixed to the second surface 19. The holding body 8 is formed with six small protrusions 20a, 20b, 20c and 21a, 21b, 21c force ^ whose tip is spherical. The three yarns / J, projections 20a, 20b, 20c and 2la, 21b, 21c are formed on a plane 22 and a plane 23 that are substantially orthogonal to each other. As shown in FIGS. 3A and 3B, the first reference surface 20A formed by the tips of the small protrusions 20a, 20b, and 20c is formed in parallel with the first surface 18. The second reference surface 21A formed by the tips of the small protrusions 21a, 21b, 21c is formed in parallel to the second surface 19.

The holder 8 is provided with a first permanent magnet 9 and a second permanent magnet 10 as shown by broken lines in FIGS. 3A and 3B. The first permanent magnet 9 is attached in a direction in which the magnetic field direction is perpendicular to the first reference plane 20A. The second permanent magnet 10 is attached so that the magnetic field direction is orthogonal to the second reference plane 21A. The end surface a of the first permanent magnet 9 is disposed close to the first reference surface 20A. The end surface of the second permanent magnet 10 is disposed close to the second reference surface 21A.

[0039] Furthermore, the polarities of the first and second permanent magnets 9 and 10 are bonded and fixed so that the end surface a of the first permanent magnet 9 and the end surface b of the second permanent magnet 10 have opposite polarities. Yes. That is, as shown in FIG. 3A, if the end surface a of the first permanent magnet 9 is an N pole, the end surface b of the second permanent magnet 10 is disposed at the S pole. As shown by a broken line in FIG. 2, a hole 24 is formed in the central portion of the holding body 8 in a direction parallel to the first and second surfaces 18 and 19 corresponding to the hole 13. Te!

[0041] As shown in FIGS. 3A and 3B, the distance L3 between the center of the hole 24 and the first reference surface 20A and the distance L4 between the first reference surface 21A are equal and the holder of the base 3 The distance L5 between the restriction surface 16 and the hole 24 is formed to be equal.

[0042] The diameter of the hole 24 is set to be about 10% larger than the shaft diameter of the shaft 12 of the cover 11 described later. As the material of the holding body 8, a resin material can be used.

[0043] The cover 11 is formed with a holding shaft 12 which is inserted into the shaft 11a and the hole 24 of the holding body 8 so as to hold the holding body 8 in a rotatable manner. The cover 11 is fixed to the base 3 by fitting into the hole 13 of the base 3 and the tip of the shaft 11 a of the cover 11 is fitted into the hole 25 of the base 3. The base 3 and the cover 11 connected in this manner are configured so that part of the adhesive supplied to the two recesses 3a and 3b of the base 3 is in two places for storing the adhesive formed in the cover 11. It flows into the 1 lb groove and is cured and secured.

[0044] In the assembled state, the holding body 8 is set to have a clearance of about 0.1 mm in the direction of the holding shaft 12, and the holding body 8 has a diameter of the holding shaft 12 as described above. For example, if the holding shaft diameter is φ 1. Omm, the diameter of the hole 24 of the holding body 8 is φ 1.1 mm. By setting the engagement state to such a large backlash, when the holding body 8 rotates about the shaft 12, the holding body 8 can rotate smoothly with almost no sliding resistance. Similarly, since the cover material is not required to have high accuracy and strength, it can be made a resin material.

In the assembled state, the holding body 8 is rotated in any direction. For example, when the holding body 8 is rotated in the clockwise direction, an attractive force is generated between the first permanent magnet 9 and the first iron core 6, and as a result, the small protrusions 20a, 20b, and 20c become the holding body regulating surface. Rotates until it contacts 16

FIG. 3A shows a state in which the small protrusions 20a, 20b, 20c are in contact with the holding body regulating surface 16, that is, a state in which the first transmission element is in a first switching position orthogonal to the light beam. As described above, the distance from the holding body regulating surface 16 of the base 3 to the hole 24 and the distance from the first reference surface 20A of the holding body 8 to the hole 24 are set to be equal to each other. In this state, the small protrusions 20a, 20b, and 20c that hold the hole 24 and the holding shaft 12 coaxially and do not touch each other are held. It is in contact with the holding body regulating surface 16.

Accordingly, since the first reference surface and the holding body regulating surface 16 are the same plane, the first transmissive element 1 parallel to the first reference surface is parallel to the holding body regulating surface 16.

[0048] Next, a mechanism for rotating the first switching position force to the second switching position will be described.

[0049] When in the first switching position in FIG. 3A, the first coil 4 has a pulse that generates a magnetic force in a direction repelling the N pole, which is the polarity of the end surface a of the first permanent magnet 9. Apply current. At this time, the magnetic force generated by this current and the permanent magnet repel, but if the current is set so that the repulsive force exceeds the attractive force between the first permanent magnet 9 and the first iron core 6, a pulse current is applied. As a result, the holding body 8 is given a counterclockwise rotational force and starts rotating. The pulse current application time is set to be short enough until the holding body 8 starts to rotate and until the holding body 8 exceeds the intermediate position between the first switching position and the second switching position.

[0050] As a result, when the holding body exceeds the middle between the first switching position and the second switching position, the attractive force between the second permanent magnet 10 and the second iron core 7 is increased, and the holding body 8 is increased. The holding body 8 continues to rotate until the position where the small protrusions 21a, 21b, 21c come into contact with the holding body regulating surface 16 together with the rotation due to the inertia.

FIG. 3B shows a state in which the second permanent magnet 10 and the second iron core 7 are attracted and the small protrusions 21a, 21b, 21c are in contact with the holding body regulating surface 16, that is, the second transmission element is a light beam. The second switching position orthogonal to

In this state, since the second reference surface 21 A is in the same plane as the holding body regulating surface 16 in exactly the same way as the first switching position shown in FIG. Parallel to plane 16.

[0053] Switching from the second switching position to the first switching position again means that a pulse current having a direction opposite to that of the pulse current that flows when switching from the first switching position to the second switching position is reversed. Apply to coil 5 of 2. On the end face of the coil 5 on the holding body regulating surface 16 side, a reverse magnetic field is generated, but the second permanent magnet 10a has a polarity opposite to that of the first permanent magnet 9a. Similarly, a repulsive force is generated between the coil 5 and the second permanent magnet 10, and the holding body rotates. As an example, the voltage applied to the coil and the pulse current application time are as follows: = Iron core diameter) is φ 3. 3mm, coil outer diameter is φ 2.3mm, coil length is 3.2mm, coil linear is φ θ. 08mm, coil resistance is 7.2Ω and applied voltage is 5V The pulse current is 700 mA and the application time is about 40 msec. Since the switching operation is completed in such a short application time, the power consumption of the coil is very small, and the coil heat generation is almost V. Therefore, there is no adverse effect on the laser life reduction due to temperature rise. .

Next, the relative angle error between the angle of the first transmission element 1 at the first switching position with respect to the light beam and the angle with respect to the light beam of the second transmission element 2 at the second switching position will be considered. Sympathize.

[0055] Similar to the angle error δ1 shown in FIG. 4 due to the component accuracy between the first virtual plane formed by the small protrusions 20a, 20b, and 20c and the first surface to which the first transmission element is attached. Angle error δ 2 due to component accuracy between the second reference surface formed by the small protrusions 21a, 2 lb, 21c and the second surface to which the second transmissive element is attached, and the plane of the holding body regulating surface 16 Angle error due to degree error The total of the above three angle errors δ1, δ2, and δ3 is the force of switching relative angle error between the first transmissive element 1 and the second transmissive element 2, However, all of these errors are determined by the part accuracy. In the case of a resin molded part, the angle error is reduced to about ± 0.2 ° in total by adjusting the mold precision. It is possible enough.

[0056] In this embodiment, the power having the first transmittance is obtained by switching the light power of the light beam by switching between the transmissive element coated with the optical filter and the transmissive element coated with no optical filter. 1 The transmissive element and the second transmissive element having a second transmittance higher than the first transmittance are obtained by switching the optical power of the light beam by switching two transmissive elements having different light transmittances. Moyo!

In this embodiment, the light beam is a semiconductor laser that emits blue light. However, it may be a semiconductor laser that emits light in the wavelength range from green to ultraviolet!

In this embodiment, the light beam transmission adjusting means switches the light power of the light beam between reading and writing data. However, the optical power of the light beam may be switched between the case where the information recording medium has one recording layer and the case where the information recording medium has two recording layers.

Industrial applicability According to the present invention, the light beam transmission adjusting means can improve the switching angle accuracy without requiring strict, component accuracy and assembly accuracy with a simple configuration, and also has low power consumption and high reliability. A low-cost and highly reliable optical pickup, and an information processing apparatus having such an optical pickup can be obtained.

Claims

The scope of the claims

[1] A light source that emits a light beam, a light beam transmission adjustment unit that adjusts a transmission amount of the light beam, and a light source that collects the light beam transmitted through the light beam light beam transmission adjustment unit on an information recording medium. In an optical pickup having an optical means,

The light beam transmission adjusting means includes:

A first transmissive element having a first transmittance;

A second transmissive element having a second transmittance higher than the first transmittance;

A first position where the light beam is rotated about a rotation axis parallel to the first transmission element and the second transmission element; a second position where the light beam is transmitted through the first transmission element; and a second position where the light beam is transmitted through the second transmission element. Rotation drive switching mechanism to switch between

Have

The rotational drive switching mechanism is configured to be selectively urged to the switching position between the first position and the second position by the attractive force of a permanent magnet, and the light beam having the first optical power and the second optical path are configured. Configured to selectively output a light beam with ヮ

Optical pickup.

[2] The rotation drive switching mechanism is

A holding body for holding the first transmissive element and the second transmissive element and having a hole parallel to the first transmissive element and the second transmissive element;

A first permanent magnet for generating an attracting force for maintaining the first position and a second permanent magnet for generating an attracting force for maintaining the second position, which are respectively attached to the holding body; The holding body is engaged with a holding shaft passed through a hole, and the holding body is placed on the center line of the light beam in a state where the holding body is rotatable around the holding shaft. A base that regulates the position to the first position or the second position;

A first iron core for adsorbing the first permanent magnet mounted on the base, and a first coil that is concentric with the first iron core and applies a repulsive force to the first permanent magnet, and the second permanent magnet. A second iron core for adsorbing a magnet, and a second coil concentric with the second iron core and imparting a repulsive force to the second permanent magnet;

The optical pickup according to claim 1, comprising:

[3] In the holding body,

A first transmissive element mounting surface for mounting the first transmissive element orthogonal to each other; a second transmissive element mounting surface for mounting the second transmissive element;

A first reference surface that is in contact with the base to hold the first position parallel to the first transmissive element mounting surface;

A second reference surface that is in contact with the base to hold the second position parallel to the second transmissive element mounting surface;

Formed on the base,

A reference plane on which the first reference surface and the second reference surface of the holding body contact each other is formed.

The optical pickup according to claim 2.

[4] The first permanent magnet is attached to the holding body so that the magnetization direction is perpendicular to the first reference plane and the center force of the first transmission element is offset.

The second permanent magnet is attached to the holding body so that the magnetization direction is perpendicular to the second reference plane and is offset from the central force of the second transmission element,

The first coil is mounted on the base so that an axis is perpendicular to the reference plane and is opposed to the first permanent magnet at the first position;

The second coil is mounted on the base so that an axis is perpendicular to the reference plane and is opposed to the second permanent magnet at the second position.

The optical pickup according to claim 2.

[5] The flat surfaces of the first reference surface and the second reference surface of the holding body are respectively determined by three small protrusions, and the tip shape of each of the small protrusions is a spherical surface.

The optical pickup according to claim 3.

6. The optical pickup according to claim 1, wherein the light source is a semiconductor laser that emits light in a wavelength region of green power and ultraviolet light.

[7] The light source is a semiconductor laser that emits light in a blue wavelength region.

The optical pickup according to claim 1.

[8] The optical pickup according to [1], further comprising a photodetector for detecting reflected light from the information recording medium;

A signal processing circuit that generates at least one of a reproduction signal and a servo signal based on the reflected light detected by the photodetector.

Information processing apparatus provided.

[9] A plurality of types of information recording media having different numbers of recording layers can be loaded, and a light beam having a magnitude of optical power corresponding to the number of the recording layers with respect to the loaded information recording medium Is an information processing device that reads and Z or writes data.

When an information recording medium having one recording layer is loaded, the rotational drive switching mechanism switches to the first position to emit a light beam having the first optical power to the recording layer. When an information recording medium having a plurality of recording layers is loaded, the rotation drive switching mechanism switches to the second position and the light beam having the second optical power is applied to one of the recording layers. Radiate

The information processing apparatus according to claim 8.