JPH10172151A - Optical pickup and optical information processing device using this optical pickup - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably protect an object lens from being tilted by installing a shaft which is composed of magnetic material and supports the movable section shaft-slidably, a magnetic body which is disposed to generate a definite magnetic interaction with the shaft and also a sleeve at the movable section supporting the shaft. SOLUTION: In an optical pickup of this form, the shaft 8 is composed of magnetic material and a pre-pressurizing magnet 11 is embedded in a part of the sleeve 12. Further, the outer peripheral surface of the shaft 8 and the inner peripheral surface of the sleeve 12 are made very even. For this reason, the shaft 8 is attracted to the inner peripheral surface of the sleeve 12 on the side where the magnet 11 is embedded so as to stablize the condition of contact to this inner peripheral surface. This condition is unchanged even when the magnet 11 inside the sleeve 12 is at any position of the shaft 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to optical information recording on DVDs (digital video disks), DVD-ROMs, CDs (compact disks), CD-ROMs, magneto-optical disks, phase-change optical disks, optical cards and the like. The present invention relates to an optical pickup used in an optical information processing device that at least reproduces information recorded on a medium.

[0002]

2. Description of the Related Art In the field of optical disks exemplified by CDs, CD-ROMs, magneto-optical disks, etc., it is necessary to record information at a high density such as a DVD or a DVD-ROM in order to further increase the density. The development of an optical disk capable of performing the above and an optical disk device for at least reproducing information recorded on the optical disk are being performed.

In such a situation, an optical disk (eg, DVD) capable of recording a large amount of information
There has been proposed an optical disk device that enables a single optical disk device to handle a plurality of types of optical disks such as an optical disk (for example, a CD) that has been widely used in the past.

[0004] Hereinafter, an example of such an optical disk device that can handle two types of optical disks, DVD and CD, will be described.
In this DVD / CD dual-purpose optical disk device, the DV
It is necessary to make the light beams irradiating D and CD into an optimum focusing state for each type of optical disk, and control is performed so as to be a light beam corresponding to the type of optical disk to be handled.

[0005] For example, two types of objective lenses having an aperture ratio that provides an optimum convergence state for each optical disk, and, among these two types of objective lenses, switching to an objective lens of a type corresponding to the type of optical disk to be handled. An optical pickup having an objective lens driving means capable of performing the above operation is used for a DVD / CD optical disk device. By controlling the optical pickup, the light beam is controlled so as to correspond to the type of the optical disk to be handled.

FIG. 10 shows an optical pickup provided with a DVD objective lens and a CD objective lens as such an optical pickup and capable of switching between these two types of objective lenses. (For example, Japanese Patent Application No. 7-2931)
This optical pickup has a cylindrical fixed portion having a columnar movable portion 13 having two types of objective lenses 1 and 2 and a shaft 8 fitted to a sleeve 12 provided on the movable portion 13. And a unit 14. With this configuration, the movable portion 13 is movable with respect to the fixed portion 14 in the axial direction of the shaft 8 and is rotatable about the shaft 8 as a center axis.

[0007] The movable section 1 is fixed to the fixed section 14.
By using an operation in which the movable section 13 rotates about the shaft 8 with respect to the fixed section 14 among the operations that the 3 can take, the objective lens can be switched. That is, the position of the two types of objective lenses 1 and 2 provided on the movable unit 13 is changed with respect to the fixed unit 14 by rotating the movable unit 13 with respect to the fixed unit 14 about the shaft 8 as a center axis. It is possible to select a desired objective lens from the objective lenses 1 and 2 and insert it into the optical path of the light beam.

FIG. 11 shows an optical pickup in which the movable portion 13 and the fixed portion 14 are disassembled. A first drive coil pair 4 and a second drive coil pair 5 are provided on the outer peripheral surface of the movable portion 13 symmetrically with respect to the sleeve 12, respectively. A predetermined current is passed through each of the drive coils as needed, and a magnetic field is generated around the drive coils. On the other hand, a focusing magnet pair 6 and a tracking magnet pair 7 are provided axially symmetrically with respect to the shaft 8 on the inner peripheral surface of the fixed portion 14 at positions facing the respective drive coils described above.

The focus magnet pair 6 generates a magnetic interaction with a magnetic field generated around a drive coil pair provided opposite to the focus magnet pair 6 among the drive coil pairs 4 and 5 described above. In this case, the objective lenses 1 and 2 are movable in the optical axis direction, that is, the movable portion 13 is
Is magnetized so that it can move in the axial direction of

Also, a tracking magnet pair 7
When a magnetic interaction occurs between a magnetic field generated around a drive coil pair provided opposite to the tracking magnet pair 7 among the drive coil pairs 4 and 5, the objective lens 1 and the 2 is magnetized so as to be movable in a direction perpendicular to the optical axis, that is, the movable part 13 is rotatable about the shaft 8 with respect to the fixed part 14. The switching operation of the objective lenses 1 and 2 is performed by applying a kick pulse to a drive coil pair provided opposite to the tracking magnet pair 7.

Further, the movable portion 13 has a position of each drive coil described above, that is, a focusing magnet pair 6.
The magnetic piece 10 is provided at a position facing each magnet of the tracking magnet pair 7. Each of the magnetic pieces 10 forms a magnetic spring by being paired with each of the magnets described above. That is, a magnetic attraction force acts between the magnet constituting the magnetic spring and the magnetic piece so that the movable portion 1 is moved.
When the movable member 3 is displaced with respect to the fixed portion 14, a restoring force for restoring the movable portion 13 to a predetermined position of the fixed portion 14 can be given, and the movable portion 13 is floated to the predetermined position in a floating state. Enables positioning.

[0012]

In such a magnetic spring, conventionally, the size of the magnetic piece 10 provided opposite to each of the above-mentioned magnets is deliberately unbalanced so as to be fixed. Attempts have been made to prevent the optical axis of the objective lens provided on the movable section 13 from being shifted by preventing the movable section 13 from tilting with respect to the movable section 13.

For example, the size of one magnetic piece facing a certain magnet among the plurality of magnetic pieces 10 provided in the movable portion 13 is changed to the size of another magnetic piece facing a magnet other than this magnet. It was configured differently. With such a configuration, the fixing portion 1
The magnet provided on the movable member 13 exerts a non-uniform magnetic force on the magnetic piece provided on the movable portion 13. The non-uniform magnetic force is a force that preliminarily presses the movable portion 13 against the shaft 8 provided on the fixed portion 14 from a predetermined direction with a predetermined pressure, that is, a preload.

On the other hand, there is a slight gap between the shaft 8 provided on the fixed part 14 and the sleeve 12 provided on the movable part 13 due to the sliding of the movable part 13 with respect to the fixed part 14. . The inclination of the movable section 13 with respect to the fixed section 14 caused by the gap is prevented by the action of the preload described above, and attempts have been made to prevent the optical axis of the objective lens provided on the movable section 13 from being shifted.

However, the prevention of the inclination of the movable portion 13 by such a preload structure is disadvantageous in that when the movable portion 13 is displaced in the axial direction of the shaft 8, the preload fluctuates, and the manner of applying the preload is not stable. Had a point. Hereinafter, this disadvantage will be described with reference to the drawings.

FIG. 12 is a sectional view taken along the line AA ′ of the optical pickup shown in FIG. In the conventional optical pickup shown in FIG. 12, the movable part 13 is displaced in the axial direction of the shaft 8 with respect to the fixed part 14, thereby performing focus control of a light beam to be irradiated on the optical disk. At this time, as the movable portion 13 is displaced in the axial direction of the shaft 8 with respect to the fixed portion 14, the magnetic member 1 provided on the movable portion 13 is displaced.
0 is also displaced in the axial direction of the shaft 8. Due to this displacement, the relative positional relationship between the magnet 6 and the magnetic piece 10 also changes.

On the other hand, due to the magnetized state of the magnet 6, a magnetic field is generated from the magnet 6 by arc-shaped lines of magnetic force indicated by dotted lines, and the magnet 6 exerts a magnetic action on the magnetic piece 10. Since the magnetic field of the magnet 6 affecting the magnetic piece 10 is arc-shaped, the strength and direction of the magnetic field change in a direction parallel to the axial direction of the shaft 8 depending on the relative positional relationship with the magnet 6. ing.

The strength and direction of the magnetic field that changes depending on the relative positional relationship with the magnet 6 also affects the magnetic force acting on the magnetic piece 10. That is, the movable unit 1
The magnetic piece 10 whose relative positional relationship with the magnet 6 changes with the displacement of the shaft 3 in the axial direction of the shaft 8.
Is affected by the magnetic field whose strength and direction are changed as described above, and the magnitude and direction of the force received from the magnet 6 by the magnetic action are changed. The magnetic force from the magnet 6 received by the magnetic piece 10 is
Each time the position changes relative to the magnet 6,
That is, each time the movable unit 13 is displaced in the axial direction of the shaft 8 with respect to the fixed unit 14 to perform focus control, a change occurs.

In the optical pickup, the movable portion 13 is connected to the shaft 8
The focus control is always performed by displacing the magnet 6 in the axial direction, and the relative positional relationship between the magnet 6 and the magnetic piece 10 is also constantly changing. Therefore, depending on the preload structure described above, the preload applied by the movable portion 13 to the fixed portion 14 is not stable, and it is impossible to sufficiently prevent the movable portion 13 from tilting.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object thereof is to provide an optical pickup capable of stably preventing the tilt of an objective lens regardless of the operation state of the optical pickup. In the offer.

[0021]

In order to achieve the above object, an optical pickup according to the present invention has an objective lens for converging and irradiating an optical disk with a light beam, and holding the objective lens, together with the objective lens in the optical axis direction. A movable portion, and supporting means for supporting the movable portion so as to be movable in the optical axis direction. The supporting means is provided along the optical axis direction, is made of a magnetic material, and is formed of a magnetic material. A shaft that slidably supports the shaft, and a magnetic body disposed between the shaft so that a constant magnetic interaction force is generated regardless of the shaft sliding state. And a sleeve provided on the movable portion for bearing.

In the optical pickup of the present invention having such a structure, the magnetic material provided on a part of the sleeve and the shaft made of a material which generates a magnetic attraction with the magnetic material magnetically attract each other. This stabilizes the shaft in contact with the inner peripheral surface of the sleeve. By the action of the shaft being kept in stable contact with the inner peripheral surface of the sleeve, the position fluctuation of the movable part is stabilized, and the inclination of the objective lens provided on the movable part can be prevented.

The function of the shaft to keep in stable contact with the inner peripheral surface of the sleeve does not change even if the position of the shaft with respect to the sleeve is changed by the operation of the optical pickup. It is possible to obtain a stable effect of preventing the objective lens from being tilted irrespective of the above operation.

[0024]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an optical pickup according to an embodiment of the present invention. FIG. 2
FIG. 2 is an exploded view of a partly cutaway optical pickup according to an embodiment of the present invention. In addition, in the optical pickup according to the embodiment of the present invention shown in FIGS. 1 and 2 and the like, the components corresponding to the components in the conventional optical pickup shown in FIGS. It shall be.

The optical pickup according to the embodiment of the present invention comprises a movable section 13 and a fixed section 14. When the sleeve 12 provided on the movable portion 13 and the shaft 8 provided on the fixed portion 14 are fitted together, the movable portion 13 and the fixed portion 14 are centered on the shaft 8 with respect to the fixed portion 14. The shaft 8 is configured to be rotatable and slidable in the axial direction of the shaft 8.

The movable part 13 includes a lens holder 3 having a substantially cylindrical shape, a DVD objective lens 1, a CD objective lens 2, a first drive coil pair 4, a second drive coil pair 5, and a magnetic material. It comprises a piece 10, a sleeve 12, and a preload magnet 11.

The DVD objective lens 1 is an objective lens for focusing a light beam on a DVD of an optical disk under conditions that are optimal for reproducing an information signal, and has, for example, a condition that the numerical aperture is approximately 0.6. . The CD objective lens 2 is an objective lens that focuses a light beam on a CD of an optical disc under conditions that are optimal for reproducing information signals, and has, for example, a condition of a numerical aperture of approximately 0.45. The two different types of objective lenses 1 and 2 are provided at a portion corresponding to the bottom surface on one side of the cylindrical shape. At this time, the objective lens 1
And 2 are provided so as to have respective optical axis centers at positions equidistant from the center of the substantially circular bottom surface.

Each of the first drive coil pair 4 and the second drive coil pair 5 is composed of two electromagnetic coils. When a predetermined current is introduced, the first drive coil pair 4 and the tracking magnet pair 7 described later A magnetic field that gives a magnetic interaction is generated in the surroundings. By controlling the magnetic field, operation control of the movable unit 13 with respect to the fixed unit 14, that is, focus control, tracking control, and objective lens switching control are performed.

The two drive coil pairs 4 and 5 are arranged at equal intervals on a curved surface portion corresponding to the cylindrical outer peripheral surface. In other words, each drive coil pair is disposed axially symmetrically with respect to an axis (symmetric axis) passing through the center of the bottom surface and perpendicular to the bottom surface, and one drive coil pair is disposed around the symmetry axis. 90 from the position
The other drive coil pair is arranged at a position rotated by degrees.

The magnetic material pieces 10 are provided as magnetic material pieces having substantially the same size at the positions of the respective drive coils of the first drive coil pair 4 and the second drive coil pair 5 described above. . The positions where the respective magnetic material pieces 10 are provided are positions facing the respective magnets of the focusing magnet pair 6 and the tracking magnet pair 7. Each magnetic piece 10
A magnetic spring is formed in pair with each of the above magnets. That is, when the movable part 13 is displaced with respect to the fixed part 14 due to the magnetic attraction force acting between the magnet constituting the magnetic spring and the magnetic piece,
A restoring force for restoring the movable portion 13 to a predetermined position of the fixed portion 14 can be given, and the movable portion 13 can be positioned at the predetermined position in a floating state.

The sleeve 12 is a bearing member made of resin or the like having a hollow cylindrical shape. The sleeve 8 is used to insert and fit the shaft 8 into the hollow portion so that the movable portion can slide on the shaft. One end of the sleeve 12 is provided on the bottom surface in a state where the center axis of the cylindrical shape coincides with the symmetry axis. The sleeve 12 is made of a material having no magnetism, such as a resin.

The preload magnet 11 is provided on the sleeve 1
The sleeve 12 is made of a magnetic material such as a magnet, and has an arc shape that follows the circular tube shape of the sleeve 12. The preload magnet 11 is for applying magnetic attraction to the shaft 8 made of metal or the like.

The preload magnet 11 is provided inside the sleeve 12 as, for example, two magnets spaced at a predetermined distance L. When the preload magnet 11 is formed by the two magnets as described above, the two magnets are arranged so as to have a positional relationship parallel to the center axis of the sleeve 12 and a part of the sleeve 12 is formed. Embed in That is, the two magnets are arranged such that a straight line formed when the positions where the two magnets are provided is connected is parallel to the central axis of the sleeve 12. Thus, when the magnetic attraction of the preload magnet 11 acts on the shaft 8, the shaft 8 is attracted to the inner peripheral surface of the sleeve 12 by the preload magnet 11 in a stable state.

As the value of the predetermined distance L increases, the preload magnet 11 attracts the shaft 8 to the inner peripheral surface of the sleeve 12 so that the shaft 8 can be held more stably. Therefore, the value of the interval L is preferably set to a large value.

The fixed portion 14 is provided with a shaft 8, a focusing magnet pair 6, and a tracking magnet pair 7 on a substantially cylindrical yoke 9 having a closed bottom surface on one side.
And a light beam transmission port 15. The movable part 13 is inserted into the cylindrical shape of the fixed part 14 from the opening in the fixed part 14 in a state where the shaft 8 is fitted to the sleeve 12 provided on the movable part 13, and the movable part 13 is connected to the shaft 8. It is rotatable as a central axis and slidable in the axial direction of the shaft 8.

The shaft 8 is a rod-shaped shaft member having one end provided on a closed bottom surface of the fixed portion 14 on one side. At this time, the shaft 8 is provided at the center of the substantially circular closed bottom portion and in a vertical positional relationship with the bottom portion. The shaft 8 is made of a material that generates an interaction force such as a magnetic attractive force with the preload magnet 11 described above.
Examples of such a material include a material having magnetism, for example, a metal such as stainless steel having magnetism.

The focusing magnet pair 6 is a magnetic material such as a magnet provided as a pair on the inner peripheral surface of the fixed portion 14 at a position facing one of the driving coil pairs 4 and 5 described above. It is. When a magnetic interaction occurs with a magnetic field generated around a driving coil pair provided opposite to the focusing magnet pair 6, the objective lenses 1 and 2 can move in the optical axis direction. That is, the focusing magnet pair 6 is magnetized so that the movable portion 13 can move in the axial direction of the shaft 8 with respect to the fixed portion 14.

The tracking magnet pair 7 faces the drive coil pair other than the drive coil pair provided at a position facing the focus magnet pair 6 among the drive coil pairs 4 and 5 on the inner peripheral surface of the fixed portion 14. And a magnetic body such as a magnet provided in a pair at the position where the magnetic field is to be generated. When a magnetic interaction occurs with a magnetic field generated around a driving coil pair provided opposite to the tracking magnet pair 7, the objective lenses 1 and 2 can move in a direction perpendicular to the optical axis. That is, the movable portion 13 is magnetized so as to be rotatable about the shaft 8 with respect to the fixed portion 14.

The light beam transmitting port 15 is provided on the bottom of the fixed portion 14 for the objective lens 1 provided on the movable portion 13.
An aperture having a size large enough to allow the light beam to pass therethrough is provided at a position where the light beam converged on the optical disk by any one of the objective lenses 2 and 3 passes.

The optical pickup according to the embodiment of the present invention having such a configuration has the movable section 13 as follows.
To prevent tilting. Here, FIG. 3 is a schematic diagram showing the state of the gap existing between the shaft 8 and the sleeve 12 as viewed from the axial direction of the shaft 8.

In the optical pickup according to the embodiment of the present invention, the shaft 8 is made of a magnetic material such as a metal, and a preload magnet 11 made of a magnet or the like is embedded in a part of the sleeve 12. Further, in order to enable the rotation and sliding of the movable part 13 with respect to the fixed part 14 without hindrance, the outer peripheral surface of the shaft 8 and the inner peripheral surface of the sleeve 12 are in a state where the surfaces are protruded, that is, the unevenness is extremely large. It is in a low state. For this reason, the shaft 8 is attracted to the inner peripheral surface of the sleeve 12 on the side where the preload magnet 11 is embedded, and is stabilized in a state of being in contact with the inner peripheral surface.

This state is unchanged regardless of the position of the preload magnet 11 in the sleeve 12 at any position on the shaft 8. For example, even when the movable portion 13 rotates around the shaft 8 by the tracking control operation and the switching operation of the objective lens, or when the movable portion 13 slides in the axial direction of the shaft 8 by the focus control operation. However, the situation where the shaft 8 is attracted to the inner peripheral surface of the sleeve 12 on the side where the preload magnet 11 is embedded and the shaft 8 is in contact with the inner peripheral surface remains stable.

Therefore, in the optical pickup according to the embodiment of the present invention, it is possible to stably prevent the tilt of the movable portion 13 in any situation,
Accordingly, it is possible to prevent the optical axis of the objective lens from shifting.

Here, when the shaft 8 is attracted to the inner peripheral surface of the sleep 12 by the magnetic attraction by the preload magnet 11, the rotation and the sliding action of the movable portion 13 with respect to the fixed portion 14 are not adversely affected. For this purpose, the preload magnet 11 must have a magnetic force that does not deteriorate the sliding of the movable portion 13. For example, assuming that the movable portion 13 is rotated and slid with respect to the fixed portion 14 by receiving a driving force of several tens gf, the preload magnet 11
Magnetic attraction to the shaft 8 due to
It is advisable to adjust the magnetic force of the preload magnet 11 so as to have a very small force.

In the above-described embodiment of the present invention, the preload magnet 11 is composed of two magnets. However, even when the preload magnet 11 is composed of a number of magnets other than two,
Needless to say, the above-described action of preventing the movable portion 13 from tilting according to the present invention can be stably obtained. For example, as an example in which the preload magnet 11 is configured by a number of magnets other than two, as shown in FIG. 4, in the axial direction of the shaft 8, that is, in the direction parallel to the sleeve 12, , Preload magnet 1 with one magnet
1 may be configured and arranged on a part of the sleeve 12.

In the above-described embodiment of the present invention, the preload magnet 11 is embedded in a part of the sleeve 12. However, the configuration of the preload magnet 11 and the sleeve 12 is not limited to this. 11
However, any configuration may be used as long as the shaft 8 is attracted to the inner peripheral surface of the sleeve 12 by magnetic attraction.

For example, as shown in FIG. 5A, the preload magnet 11 and the sleeve 12 are formed at the same time so that the entire preload magnet 11 is embedded in the sleeve 12. Also, as shown in FIG. 5B, the preload magnet 1
1 is provided in the groove, and a magnet 11 for preload is formed in this groove.
Is fitted. Alternatively, FIG.
As shown in (1), a groove for fitting the preload magnet 11 is provided in the inner peripheral surface of the sleeve 12, and the preload magnet 11 is fitted into this groove. Or Figure 5
As shown in (d), the preload magnet 11 is attached to the outer peripheral surface of the sleeve 12.

The optical pickup according to the above-described embodiment of the present invention reproduces information recorded on an optical disk by generating a light beam, irradiating the optical disk with light, and converting reflected light from the optical disk into an electric signal. It is used as follows in an optical disk device that performs the following.

FIG. 6 schematically shows a cross-sectional view of an optical pickup according to an embodiment of the present invention and a configuration of an optical disk apparatus using the optical pickup. The configuration of the optical disk device includes an optical system 6A, a driving system 6B, and a signal processing system 6A.
C is roughly classified.

The optical system 6A comprises an optical pickup 26 and an optical frame 16. The optical system 6A includes a drive system 6A.
B receives the position control of the optical disk 25 from the signal processing system 6C and the control signal regarding the light beam irradiation on the optical disk 25 from the signal processing system 6C, and performs the focused irradiation of the light beam on a predetermined position of the optical disk 25. Further, the optical system 6A receives the reflected light from the optical disc 25 generated by the light beam irradiation, converts the reflected light including the information recorded on the optical disc 25 into an electric signal, and transmits the electric signal to the signal processing system 6C. I do.

The drive system 6B includes a motor (not shown) and a gear connected to a rotating shaft of the motor. The drive system 6B is adapted to control the signal processing system 6 according to the position of the light beam irradiated on the optical disk 25 by the optical system 6A.
C, the optical disk 25 is rotated at a predetermined rotation speed.
Is driven to rotate. The drive system 6B is connected to the optical disk 25.
The position of the optical system 6A with respect to the optical disk 25 is controlled by the control of the signal processing system 6C so that the optical system 6A irradiates the desired irradiation position with the light beam.

The signal processing system 6C processes an operation command received from an external computer or the like, controls the optical system 6A and the driving system 6B, and also transmits information transmitted from the optical system 6A and recorded on the optical disk 25. A predetermined signal processing is performed on the included electric signal, and the processed result is sent to an external computer or the like.

Next, the optical system 6A will be described in more detail. The optical frame 16 includes a laser diode 17, a collimating lens 18, beam splitters 19 and 20, detection lenses 21 and 22, and photodetectors 23 and 24.

In the optical frame 16, a divergent light beam is generated from a laser diode 17, which is a light beam generation source. The generated light beam is converted into parallel light by the collimator lens 18, then focused by the objective lens 1 or 2 of the optical pickup, and irradiated on the optical disk 25. The objective lens for focusing the light beam is a DVD objective lens 1 when the optical disk 25 irradiated with the light beam is a DVD, and a CD objective lens 2 when the optical disk 25 irradiated with the light beam is a CD. Are selectively switched by an objective lens switching operation described later.

The reflected light from the optical disk 25 generated by irradiating the optical disk 25 with a light beam is returned to the optical frame 16 after being made parallel by the objective lens 1 or 2. The light beam returned to the optical frame 16 enters the beam splitters 19 and 20. Each of the beam splitters 19 and 20 separates the incident light beam into two light beams traveling in different directions.

One light beam split by the beam splitter 19 enters the beam splitter 20, and the other light beam enters the detection lens 21. Detection lens 21
Focuses the incident light beam and forms a photodetector 2
Irradiate 3 The photodetector 23 detects the focus control state of the light beam irradiating the optical disk 25 with a light detection unit arranged in a predetermined shape, converts the light signal of the light beam into an electric signal, and performs signal processing of the optical disk device. Transmit to system 6C.

One of the light beams split by the beam splitter 20 is incident on the detection lens 22. Detection lens 2
2 focuses the incident light beam and irradiates the photodetector 24 with the light beam. The photodetector 24 detects the tracking control state of the light beam irradiating the optical disk 25 in the light detection unit arranged in a predetermined shape, converts the light signal of the light beam into an electric signal, and performs signal processing of the optical disk device. Transmit to system 6C.

The signal processing system 6C of the optical disk device
Relates to a more detailed configuration of the optical system 6A, receives electric signals transmitted from the photodetectors 23 and 24, checks the focus and tracking control states of the light beam irradiated on the optical disc 25, The drive control of the objective lenses 1 and 2 in the optical pickup is performed so that the optical disk 25 is irradiated in this state. The signal processing system 6C switches between the objective lenses 1 and 2 in the optical pickup in accordance with the type of the optical disk 25 mounted on the optical disk device.

Next, drive control and switching control of the objective lens in the optical pickup will be described.
FIG. 7 shows a positional relationship between the drive coil pairs 4 and 5 and the magnet pairs 6 and 7 for explaining the focus control operation and the tracking control operation in the optical pickup of the present invention.

The focus control is performed by using the focus magnet pair 6 magnetized in the axial direction of the shaft 8 and using the first drive coil pair 4 or the second drive coil pair 4 in a positional relationship facing the focus magnet pair 6. This is performed by passing a predetermined weak current through any one of the driving coil pairs 5.

In FIG. 7, the first drive coil pair 4
Is located at a position facing the focusing magnet pair 6. The weak current is applied to the first drive coil pair 4 to cause an interaction with the magnetic field generated by the focusing magnet pair 6, so that a force is applied to the first drive coil pair 4 in the axial direction Z of the shaft 8. Generate. The generated force causes the movable portion 13 provided with the first drive coil pair 4 to move in the axial direction of the shaft 8 with respect to the fixed portion 14 provided with the focusing magnet pair 6.

By controlling the moving amount and the moving direction, the moving amount and the moving direction of the objective lenses 1 and 2 provided on the movable portion 13 with respect to the fixed portion 14 are controlled. Focus control of the light beam being focused and irradiated is performed.

The tracking control is performed by using a tracking magnet pair 7 magnetized in a direction perpendicular to the axial direction of the shaft 8, and the first drive having a positional relationship facing the tracking magnet pair 7. This is performed by passing a predetermined weak current through either the coil pair 4 or the second drive coil pair 5.

In FIG. 7, the second drive coil pair 5
Is located at a position facing the tracking magnet pair 7. The weak current is applied to the second drive coil pair 5 to cause an interaction with the magnetic field generated by the tracking magnet pair 7, so that the second drive coil pair 5 has an axial direction Z of the shaft 8. Generates force in a perpendicular direction. Due to the generated force, the fixed portion 1 provided with the tracking magnet pair 7 is provided.
4, the movable part 13 provided with the second drive coil pair 5 is rotated in a direction M about the shaft 8 as a central axis.

By controlling the amount and direction of the rotation, the amount and direction of movement of the objective lenses 1 and 2 provided on the movable portion 13 with respect to the fixed portion 14 are controlled. The tracking control of the light beam focused and irradiated is performed.

The optical pickup that performs such a control operation moves one of the objective lenses 1 and 2 provided on the movable portion 13 into the optical path of the light beam by utilizing the above-described tracking control operation. It is possible to perform the switching operation of the objective lens as if it were installed.

The switching operation of the objective lens in the optical pickup of the present invention will be described below. FIG. 8 shows the positional relationship between the drive coil pairs 4 and 5 and the magnet pairs 6 and 7 for explaining the switching operation of the objective lens in the optical pickup of the present invention. Also, in FIG.
5 shows a temporal change of a current flowing through a drive coil during an objective lens switching operation.

For example, when the objective lens 2 is disposed in the optical path of the light beam irradiated on the optical disk, the second drive coil pair 5 is opposed to the tracking magnet pair 7 and the focusing magnet pair 6 is It is assumed that the first drive coil pair 4 is opposed. FIG. 8A shows the positional relationship between each magnet pair and the drive coil pair at this time.

At time t1 shown in FIG. 9, a current having a predetermined value in the direction indicated by the arrow i in FIG. 8 is supplied to the second drive coil pair 5 disposed opposite the tracking magnet pair 7. Is done. Then, the second drive coil pair 5 interacts with the magnetic field generated by the tracking magnet pair 7 in the portions 5A and 5B having a positional relationship parallel to the axial direction z of the shaft 8, thereby generating an arrow. It receives the force indicated by f. In response to this force, a force is generated in the second drive coil pair 5 in the direction indicated by arrow m, and the movable unit 13 provided with the second drive coil pair 5
Start rotation in the direction indicated by.

The rotation of the movable portion 13 causes the second drive coil pair 5 to move with respect to the tracking magnet pair 7. At time t2 during this movement, a portion 5B of the second drive coil pair faces the S pole of the tracking magnet pair 7. At this time point t2, the current supplied to the second drive coil pair 5 is reversed to the opposite polarity as shown in FIG. FIG. 8 shows the positional relationship between each magnet pair and the drive coil pair at this time.
(B).

By the reversal of the polarity of the current, an arrow which moves the second drive coil pair 5 away from the tracking magnet pair 7 between a portion 5B of the second drive coil pair 5 and the S pole of the tracking magnet pair 7 f
A force is generated in the direction indicated by. Under this force, the second drive coil pair 5 further moves toward the focusing magnet pair 6. As a result, the movable unit 13 continues to rotate in the direction indicated by the arrow m with respect to the fixed unit 14.
FIG. 8C shows the positional relationship between each magnet pair and the drive coil pair at this time.

At time t3 during the rotation, the current supply to the second drive coil pair 5 is stopped, but after time t3, the rotation of the movable portion 13 is continued by the inertial force. Due to this rotation, the second drive coil pair 5 facing the tracking magnet pair 7 is arranged at a position facing the focusing magnet pair 6 and the first driving coil pair facing the focusing magnet pair 6. When the position 4 is located at a position facing the tracking magnet pair 7, the rotation of the movable portion 13 with respect to the fixed portion 14 is stopped by the action of the magnetic spring between the magnetic piece 10 and each magnet pair. Is done. FIG. 8 shows the positional relationship between each magnet pair and the drive coil pair at this time.
(D). When such a positional relationship is established, the objective lens 1 is provided on the movable part 13 so that the objective lens 1 is arranged in place of the objective lens 2 in the optical path of the light beam irradiated on the optical disc. It is assumed that

In this way, the movable part 13 is fixed
, The objective lens 1 is disposed in the optical path of the light beam instead of the objective lens 2, and the objective lens is switched. In addition, along with the switching of the objective lens, the combination of each drive coil pair 4 and 5 and the magnet pair 6 and 7 facing the drive coil pair is also switched.

If the objective lens 1 is arranged in the optical path of the light beam, the first driving coil pair 4 faces the tracking magnet pair 7, and the second driving coil pair 5 faces the focusing magnet pair 6. In this state, the tracking magnet pair 7 related to the objective lens switching operation is in a positional relationship facing the first drive coil pair 4 as described above. Therefore, in such a state of the positional relationship, the objective lens 1
When the operation of switching the objective lens from the first lens to the second objective lens is performed, the switching operation of the objective lens is performed in the same manner as described above by supplying a current with a predetermined value and polarity to the first drive coil pair 4.

As described above, the optical pickup of the present invention
As described above, the tilt of the objective lens can be stably prevented, and the rotation and sliding of the movable section 13 with respect to the fixed section 14 and the operation of switching the objective lens can be performed without any trouble.

Although the optical pickup according to the embodiment of the present invention has two different types of objective lenses 1 and 2 in the movable portion 13, the number and type of the objective lenses provided in the movable portion 13 are However, the present invention is not limited to this, and can be applied to, for example, an optical pickup having only one type of objective lens. In this case, the inclination of the objective lens can be stably prevented.

[0077]

As described above, the optical pickup of the present invention stably holds the magnet while keeping the shaft in contact with the inner peripheral surface of the sleeve, thereby stably preventing the movable part and the objective lens from tilting. It is possible to do. Accordingly, it is also possible to prevent the optical axis of the objective lens from being shifted. Thus, the optical information processing apparatus using the optical pickup of the present invention can perform a stable and accurate reproduction operation.

[Brief description of the drawings]

FIG. 1 is a perspective view of an optical pickup according to an embodiment of the present invention.

FIG. 2 is an exploded view and a partially cutaway view of the optical pickup according to the embodiment of the present invention.

FIG. 3 is a sectional view showing a positional relationship between a shaft and a sleeve in the optical pickup according to the embodiment of the present invention.

FIG. 4 is a partially cutaway view of an optical pickup according to another embodiment of the present invention.

FIG. 5 is a diagram showing another arrangement example of a preload magnet in the optical pickup according to the embodiment of the present invention.

FIG. 6 is a cross-sectional view of an optical pickup according to an embodiment of the present invention and a diagram schematically showing an optical information processing apparatus using the optical pickup.

FIG. 7 is a diagram showing a positional relationship between a magnet pair and a drive coil pair in the optical pickup according to the embodiment of the present invention.

FIG. 8 is a diagram for explaining an objective lens switching operation in the optical pickup according to the embodiment of the present invention.

FIG. 9 is a diagram showing a temporal change of a current flowing through a drive coil when the objective lens of the optical pickup is switched according to the embodiment of the present invention.

FIG. 10 is a perspective view and a plan view of a conventional optical pickup.

FIG. 11 is an exploded view of a conventional optical pickup.

FIG. 12 is a sectional view of a conventional optical pickup.

[Explanation of symbols]

 1, 2 Light irradiation unit (objective lens) 3 Lens holder 4 First drive coil pair 5 Second drive coil pair 6 Focusing magnet pair 7 Tracking magnet pair 8 Shaft 9 Shaft 9 Magnetic piece 11 Magnetic material (Premagnet for magnet) 12 Bearing part (sleeve) 13 Movable part 14 Fixed part 16 Optical frame 26 Optical pickup 6A Optical system 6B Drive system 6C Signal processing system

Claims (9)

[Claims] 1. A light irradiating unit for irradiating an optical information recording medium with light, a movable unit that holds the light irradiating unit and is movable in the optical axis direction together with the light irradiating unit, Supporting means movably supporting the movable section in the optical axis direction, the supporting means is provided along the optical axis direction, is made of a magnetic material, and supports the movable section so that the movable section can slide. A magnetic member disposed so as to generate a constant magnetic interaction force between the movable portion and the movable portion that receives the shaft portion, regardless of the sliding state of the shaft. An optical pickup comprising: 2. An optical information processing apparatus comprising: an optical pickup for irradiating an optical information recording medium with light, wherein at least reproduction of information recorded on the optical information recording medium is performed. A light irradiating unit that irradiates the information recording medium with light, a light irradiating unit that holds the light irradiating unit, a movable unit that can move in the optical axis direction together with the light irradiating unit, and a movable unit that supports the movable unit in the optical axis direction. Supporting means, which is provided along the optical axis direction, is made of a magnetic material, and supports the movable portion so that the movable portion can slide axially, and between the shaft portion, Regardless of the shaft sliding state,
An optical information processing apparatus, comprising: a magnetic member arranged to generate a constant magnetic interaction force; and a bearing provided on the movable portion for bearing the shaft. . 3. A method for supporting an objective lens of an optical pickup for converging and irradiating a light beam onto an optical information recording medium, comprising: a movable portion which holds the objective lens and is movable together with the objective lens. By a shaft portion along the optical axis, a supporting step of supporting the shaft slidably, and regardless of the shaft sliding state in the supporting step, between a bearing portion bearing the shaft portion and the shaft portion. Applying a constant magnetic attraction force with a magnetic material provided in the bearing portion. 4. An objective lens for converging and irradiating an optical disk with a light beam, a movable portion holding the objective lens and movable in the optical axis direction together with the objective lens, and enabling the movable portion to move in the optical axis direction. A supporting means, which is provided along the optical axis direction, is made of a magnetic material, and supports the movable portion so as to be able to slide on the shaft,
With this shaft, regardless of the shaft sliding state,
An optical pickup, comprising: a magnetic member arranged to generate a constant magnetic interaction force; and a sleeve provided on the movable portion for bearing the shaft. 5. An objective lens for converging and irradiating a light beam to a different type of optical disk in a focused state according to the type of the optical disk, and the objective lens is held and movable in the optical axis direction together with the objective lens. A movable portion, and supporting means for supporting the movable portion movably in the optical axis direction. The supporting means is provided in the optical axis direction, is made of a magnetic material, and is capable of axially sliding the movable portion. A shaft to support the
A member having a substantially circular tube shape, between the shaft and
Irrespective of the sliding state of the shaft, a part of a magnetic body arranged along the shape of the circular tube so as to generate a constant magnetic interaction force is provided on the movable portion that bears the shaft. An optical pickup comprising: a sleeve; 6. A plurality of objective lenses for focusing and irradiating a plurality of different types of optical disks with light beams in a focused state corresponding to the type of the optical disk, and a member having a substantially cylindrical shape. A movable section that holds the plurality of objective lenses in a state where each objective lens has the optical axis center at a position equidistant from the symmetry axis, and is movable with the plurality of objective lenses; And a supporting means provided along the optical axis, made of a magnetic material, and supporting the movable portion so as to be axially slidable, and a substantially circular pipe. A substantially arc-shaped magnetic member arranged along the tubular shape so that a constant magnetic interaction force is generated between the shaft and the shaft regardless of the sliding state of the shaft. The circular tube having a body in part An optical pickup, comprising: a sleeve provided on the movable portion and bearing the shaft, with a central axis of the shape coinciding with the symmetry axis of the substantially cylindrical shape. 7. A plurality of objective lenses for focusing and irradiating a plurality of different types of optical disks with light beams in a focused state corresponding to the type of the optical disk, and a member having a substantially cylindrical shape. A movable section that holds the plurality of objective lenses in a state where each objective lens has the optical axis center at a position equidistant from the symmetry axis, and is movable with the plurality of objective lenses; And a support means provided along the optical axis direction, the support means being made of a magnetic material, and supporting the movable portion so as to be axially slidable, and a substantially circular pipe. A substantially arc-shaped magnetic body disposed along the shape of the tube so that a constant magnetic interaction force is generated between the shaft and the shaft regardless of the sliding state of the shaft. , The cylindrical shape A sleeve that is provided on the movable portion and that bears the shaft, and that has a substantially cylindrical shape with a one-side closed, provided that the central axis of the shape coincides with the center of symmetry of the substantially cylindrical shape. A fixed portion that holds the shaft at a closed portion and has an inner peripheral surface facing the outer peripheral surface of the movable portion, and a plurality of fixed portions provided on the inner peripheral surface of the fixed portion facing the outer peripheral surface of the movable portion. And a plurality of coils provided on an outer peripheral surface of the movable portion, and a plurality of coils provided on an outer peripheral surface of the movable portion, and a plurality of coils provided on the fixed portion. And a plurality of magnetic pieces provided on the outer peripheral surface of the movable section. 8. For two different types of optical discs,
Two objective lenses for converging and irradiating a light beam in a converging state according to the type of the optical disc, and a member having a substantially cylindrical shape. Each of the members is equidistant and perpendicular to the symmetric axis of the substantially cylindrical shape. A movable section that holds the two objective lenses in a state where the objective lens has the optical axis center, and that is movable together with the two objective lenses; and a support unit that supports the movable section so as to be movable in the optical axis direction; This support means is provided along the optical axis direction, is made of a magnetic material,
A shaft that supports the movable portion so as to be able to slide on the shaft, and a member having a substantially cylindrical shape, so that a constant magnetic interaction force is generated between the shaft and the shaft regardless of the shaft sliding state. A part of a substantially arc-shaped magnetic body arranged along the circular tube shape, and provided on the movable portion in a state where the center axis of the circular tube shape is coincident with the center of symmetry of the substantially cylindrical shape. A sleeve for bearing the shaft, and a member having a substantially cylindrical shape with a one-sided closing, and in a state where the axis of symmetry of the substantially cylindrical shape and the axis of symmetry of the shaft coincide with each other, A shaft is provided, and a fixed portion having an inner peripheral surface facing the outer peripheral surface of the movable portion, and an equidistant distance is provided on the inner peripheral surface side of the fixed portion along an arc of the inner peripheral surface. The four magnetic members provided and the four Four coils provided on the outer peripheral surface of the movable portion, facing the sexual body, and four magnetic material pieces provided at positions on the outer peripheral surface of the movable portion provided with the four coils, An optical pickup comprising: 9. A first objective lens for converging and irradiating a light beam on an optical disc under a condition of a numerical aperture of about 0.6, and a second objective lens for converging and irradiating an optical disc on a condition of a numerical aperture of about 0.45. And an approximately cylindrical member.
With each objective lens having the center of the optical axis at a position equidistant and perpendicular to the symmetry axis of this substantially cylindrical shape,
A movable section for holding the first and second objective lenses and movable together with the two objective lenses; and a supporting means for movably supporting the movable section in the optical axis direction. Is a shaft that is provided along the optical axis direction, is made of a magnetic material, and supports the movable portion so as to be able to slide on the shaft, and a member having a substantially cylindrical shape. Irrespective of the state, a part of a substantially arc-shaped magnetic body arranged along the tubular shape so that a constant magnetic interaction force is generated, and the central axis of the tubular shape is the substantially cylindrical shape A sleeve provided on the movable portion in a state coinciding with the center of symmetry of the shape, a sleeve for bearing the shaft, and a member having a substantially cylindrical shape with one side closed; In a state where the A fixed portion having an inner peripheral surface facing the outer peripheral surface of the movable portion, and an equidistant distance along the arc of the inner peripheral surface on the inner peripheral surface side of the fixed portion. And four coils provided on the outer peripheral surface of the movable portion, facing the four magnetic materials provided on the fixed portion, and the four coils provided on the fixed portion. An optical pickup comprising: four magnetic pieces provided at positions on an outer peripheral surface of the movable portion.