JPH11195235A - Optical head of optical disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify the constitution of an optical head. SOLUTION: The optical head 100 is constituted of a pair of turning arms 3a, 3b provided with objective lenses converging a light beam to the recording surfaces of the optical disk 2 and turned along the both sides of the optical disk 2, a fixed optical unit 4 provided with a light source unit emitting the light beam and fixed against a main body of the optical disk device, a selecting means for selectively guiding the light beam coming from the fixed optical unit 4 to one of a pair of turning arms 3a, 3b, and deflection mirrors 26, 25, 31 for making the light beam from the fixed optical unit to deflect in accordance with the turning of the aforementioned one of the turning arms.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk device, and more particularly, to an optical head for recording information on a recording surface of an optical disk or reproducing information on the recording surface.

[0002]

In recent years, the areal recording density has become 1
Optical disk devices exceeding 0 Gbit / (inch) ² are being developed. In such an optical disk device,
An optical head for recording information on a recording surface of an optical disk (or reproducing information on the recording surface) is configured as a rotating arm that rotates in a direction intersecting tracks of the optical disk.

Here, when both sides of the optical disk are recording surfaces, it is necessary to provide two rotating arms corresponding to both sides of the optical disk. However, conventionally, since all optical systems such as a light source unit that emits a light beam are mounted on the rotating arm, two relatively heavy rotating arms are provided, which complicates the structure of the entire optical head. There was a problem of becoming.

The present invention has been made in view of the above circumstances, and has as its object to simplify the structure of an optical head.

[0005]

In order to solve the above-mentioned problems, an optical head of an optical disk apparatus according to the present invention comprises: (1) an objective lens for converging a light beam on a recording surface of an optical disk; A pair of rotating arms that are rotatable about a moving axis and that rotate along both surfaces of the optical disc;
(2) a fixed optical unit that includes a light source unit that emits a light beam and is fixed to a main body of the optical disc device;
(3) selecting means for selectively guiding the light beam from the fixed optical unit to one of the pair of rotating arms; and (4) selecting the light beam from the fixed optical unit in accordance with the rotation of the one rotating arm. And a deflecting means for deflecting the light.

With this configuration, one fixed optical unit can be shared by a pair of rotating arms. Therefore, the entire configuration of the optical head can be simplified as compared with the case where all the necessary optical systems are mounted on both the rotating arms. In addition, the weight of the rotating arm, which is a movable part, can be reduced.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, an embodiment of the present invention will be described. FIG. 1 is a perspective view showing the basic configuration of the optical disk device of this embodiment. This optical disk device
Near field recording (NFR)
It uses a recording / reproducing method called technology.

As shown in FIG. 1, the optical disk apparatus is configured such that an optical disk 2 is rotated by a rotating shaft 22 of a spindle motor (not shown).
Is rotatably held. The upper and lower surfaces of the optical disk 2 are both recording surfaces. In the following description, a direction perpendicular to the surface of the optical disk 2 is referred to as a “vertical direction”.

Optical head 10 for recording and reproducing information
Reference numeral 0 denotes a pair of rotating arms 3a and 3b that rotate along the upper and lower surfaces of the optical disk 2, and a fixed optical unit 4 fixed to a main body (not shown) of the optical disk device. The fixed optical unit 4 is located between the rotating arms 3a and 3b in the vertical direction. A pair of rotating arms 3
The terminals a and 3b extend in parallel with each other, and their ends are connected to each other by a connecting arm 55 extending vertically, forming a substantially U-shape. Upper turning arm 3a and lower turning arm 3
The internal structures of b are symmetric with each other in the vertical direction.

At the tip of each of the rotating arms 3a and 3b,
A floating optical unit 6 having an objective lens 10 for focusing a laser beam is mounted on the upper and lower surfaces of the optical disc 2. The rotating arms 3 a and 3 b are configured to integrally rotate about a rotating shaft 5 orthogonal to the upper and lower surfaces of the optical disc 2. That is, by the rotation of the rotating arms 3a and 3b, the respective floating optical units 6 of the rotating arms 3a and 3b move along the upper and lower surfaces of the optical disk 2 as indicated by arrows X in the figure.

First, the floating optical unit 6 will be described. Since the rotating arms 3a and 3b are symmetrical to each other in the vertical direction, the upper rotating arm 3a will be described here. FIG. 2 is a side view showing the distal end portion of the upper rotating arm 3, and FIG. 3 is an enlarged side view showing the floating optical unit 6. The floating optical unit 6 is attached to the flexure beam 8 and is arranged to face the optical disc 2. The flexure beam 8 is fixed to the rotating arm 3 at the other end.
Is pressed in the direction in which the floating optical unit 6 at the tip end is brought into contact with the optical disc 2.

The floating optical unit 6 includes a floating slider 9, an objective lens 10, and a solid immersion lens (S
IL) 11 and a magnetic coil 12, and serves to converge a parallel laser beam 13 emitted from the fixed optical unit onto the optical disk 2. A rising mirror 31 is fixed to the tip of the rotating arm 3 to guide the laser beam 13 to the floating optical unit 6. The objective lens 10 is provided by the rising mirror 31.
Is converged by the refraction of the objective lens 10. A solid immersion lens (SIL) 11 is arranged in the vicinity of the converging point, and irradiates the convergent light to the optical disc 2 as finer evanescent light 15.

A magnetic coil 12 for recording by a magneto-optical recording method is formed around a solid immersion lens (SIL) 11 facing the optical disk 2. It can be applied on the surface. This evanescent light 1
5 and the magnetic coil 12 enable high-density recording and reproduction on the optical disk 2. The floating optical unit 6 floats by a very small amount due to the airflow generated by the rotation of the optical disk 2 and follows the surface runout of the optical disk 2. For this reason, focus control (focus servo) of the objective lens, which is required in the conventional optical disk device, is not required.

Next, the rotating arms 3a and 3b and the fixed optical unit 4 will be described. FIG. 4 shows the optical head 100.
5 is a side sectional view of the optical head 100 taken along line AA ′ of FIG. As shown in FIG.
Hollow shafts 36, 36 are provided at positions corresponding to the rotation shaft 5 of the rotation arms 3a, 3b in order to rotatably support the rotation arms 3a, 3b. Hollow shaft 3
Reference numerals 6 and 36 are rotatably held by a housing 42 of the fixed optical unit 4 (attached to the main body of the optical disk, not shown) via a bearing 44.

A drive coil 16, which is a flat coil for rotating the rotating arms 3a and 3b, is fixed to the connecting arm 55 connecting the rotating arms 3a and 3b.
The drive coil 16 is inserted and arranged with a gap in the magnetic circuit 16a to constitute a so-called voice coil motor.
When a current is applied to the drive coil 16, the rotating arms 3 a and 3 b can be rotated about the rotating shaft 5 by the electromagnetic action with the magnetic circuit 16 a.

As shown in FIG. 1, the fixed optical unit 4 includes a semiconductor laser 18, a collimating lens 20, a compound prism assay 21, an imaging lens 23,
A tracking detection sensor 24 and an APC sensor 25 are provided.

The divergent laser beam emitted from the semiconductor laser 18 is converted into a parallel beam by the collimating lens 20. The cross-sectional shape of the parallel light beam is an elliptical shape due to the characteristics of the semiconductor laser 18, and it is inconvenient to narrow the laser light beam onto the optical disc 2 minutely. For this reason, the incident surface 21a of the composite prism assay 21 has a predetermined inclination with respect to the incident optical axis, and refracts the incident light to shape the cross-sectional shape of the parallel light beam from an oval shape to a substantially circular shape. .

The fixed optical unit 4 is provided with a first deflecting mirror 26 for guiding the laser beam 13 emitted from the composite prism assay 21 to one of the rotating arms 3a and 3b. The first deflecting mirror 26 deflects the laser beam 13 emitted from the complex prism assay 21 vertically upward or vertically downward. The optical axis deflected by the first deflecting mirror 26 is the rotation axis of the rotation arm 3. 5
Matches.

When the mirror surface of the first deflecting mirror 26 faces obliquely upward as shown in FIG. 1, the laser beam 13 deflected by the first deflecting mirror 26 passes through the hollow portion of the hollow shaft 36 (FIG. 5). Then, the light enters the upper rotating arm 3. Conversely, when the mirror surface of the first deflecting mirror 26 faces obliquely downward, the laser beam 13 deflected by the first deflecting mirror 26 becomes a hollow shaft 36 (FIG. 5).
And enters into the lower rotating arm 3b through the hollow portion of.
The swing system of the deflecting mirror 26 will be described later.

At a position corresponding to the rotating shaft 5 of the rotating arms 3a and 3b, the laser beam 1 from the first deflecting mirror 26 is placed.
Second deflecting mirrors 35, 35 are provided to deflect 3 horizontally (in a direction parallel to the recording surface of the optical disc 2). In the upper rotating arm 3a, the laser beam 13 reflected by the second deflecting mirror 35 passes through the first relay lens 29 and the second relay lens (imaging lens) 30 and is reflected downward by the third deflecting mirror 31. After that, it reaches the floating optical unit 6. Similarly, the lower rotating arm 3b
However, the laser beam 13 reflected by the second deflecting mirror 35 passes through the first relay lens 29 and the second relay lens 30 and is reflected upward by the third deflecting mirror 31 before reaching the floating optical unit 6. .

FIG. 6 is a schematic diagram showing the optical system of the optical head 100. As shown in FIG. 6, the rotating arm 3a (3
With the rotation of b), the second deflecting mirror 35, the first relay lens 29, the second relay lens 30, and the third deflecting mirror 31
Rotate as shown by A, B and C in the figure. As described above, the first deflecting prism 26 (FIG. 1) to the second deflecting mirror 35
The laser beam 13 horizontally deflected by the second deflecting mirror 35 because the optical axis incident on the
Moves along the rotation arm 3a (3b) in the longitudinal direction and reaches the floating optical unit 6 regardless of the rotation position of the rotation arm 3a (3b).

The returning laser beam 13 reflected from the optical disk 2 returns in the reverse direction of the outward path, is reflected by the first deflecting mirror 26, and enters the composite prism assay 21. Half mirror surface 21b of composite prism assay 21
Generates the transmitted light and the reflected light directed to the data detection / tracking detection sensor 24, and separates the laser beam on the return path. Data detection / tracking detection sensor 24
Is a composite sensor that reads data information recorded on the optical disc 2 and outputs a data signal and outputs a tracking error signal. Note that to be precise, the tracking error signal and the data signal are generated by a head amplifier circuit (not shown) and sent to a control circuit or an information processing circuit.

Next, the fine tracking control will be described. The first deflecting mirror 26 is a so-called galvano mirror that performs fine tracking control by finely adjusting the incident angle of the laser beam 13 with respect to the objective lens 10 by swinging about the axis R on the mirror surface. That is, the optical head 100 performs an access operation over the inner circumference / outer circumference of the optical disc 2 by rotating the rotating arm 3 and performs only minute tracking control by rotating the first deflection mirror 26. The rotation angle of the first deflection mirror 26 is detected by an angle detection sensor (not shown) provided near the first deflection mirror 26.

The first relay lens 29 and the second relay lens 30 conjugate the relationship between the reflection surface of the first deflecting mirror 26 and the pupil plane (principal plane) of the objective lens 10 arranged in the floating optical unit 6. This is to make a relationship, and forms a relay lens optical system. That is, as described above, in the method in which the first deflection mirror 26 is slightly swung to perform minute tracking control, when the optical distance between the first deflection mirror 26 and the objective lens 10 is long, the light enters the objective lens 10. In some cases, the moving amount of the laser beam 13 is increased, so that the laser beam 13 cannot enter the objective lens 10.

Therefore, the first and second relay lenses 29,
By means of 30, the relationship between the reflection surface of the first deflection mirror 26 and the pupil surface of the objective lens 10 is set to be a conjugate relationship,
Even if the first deflecting mirror 26 rotates, the laser beam incident on the objective lens 10 does not move, so that accurate tracking control can be performed. Also, the first deflection mirror 2
The laser beam entering the mirror surface 6 and the entrance pupil surface of the objective lens 10 are both configured to be parallel light.

FIGS. 7 and 8 are a perspective view and an exploded perspective view showing a structure for driving the first deflection mirror 26. FIG.
The first deflecting mirror 26 has a function of swinging largely for switching the optical path up and down (selection of the upper and lower rotating arms 3a and 3b) and a function of finely moving for fine tracking control.

As shown in FIG. 7A, the deflection mirror 26
Is held by the mirror support 2 attached to the housing 42 of the fixed optical unit 4 (FIG. 4).
00 is swingably held. Mirror support 200
Has a pair of brackets 202 which hold the mirror frame 205 so as to be able to swing around a swing axis R including the center of the mirror surface of the deflecting mirror 26. The bracket 202 has a center pin 203 (having a conical tip) at a position corresponding to the pivot axis R, and the mirror frame 205 has a bearing 208 for receiving the center pin 203.

As shown in FIG. 8A, the mirror frame 205
Two semi-circular permanent magnets 2
20, 220 are attached. FIG. 8 (b)
As shown in FIG. 5, each of the magnets 220 is an N pole on the upper side and an S pole on the lower side, and the magnetic flux lines are perpendicular to the magnet surface (so-called radial magnetized magnets).

The inner peripheral surface 201 of the mirror support 200 has a curved surface corresponding to the semicircular outer peripheral surfaces of the magnets 220 and 220. The inner surface 201 has a magnet 22
Coils 210, 210 are provided so as to face 0, 220. Each coil 210 includes an outer coil 212
And two independent coils, the inner coil 214 and the inner coil 214. Outer and inner coils 212, 21
4 by changing the current flowing through the coils 212, 2
By the electromagnetic action of the magnet 14 and the magnet 220, the deflection mirror 26 can be swung as shown in FIG.

FIG. 9 is a diagram showing a swinging method of the deflecting mirror 26. As shown in FIG. As shown in FIG. 9A, when no current is applied to the outer / inner coils 212 and 214, no electromagnetic action occurs between the coils and the magnet 220.

When switching the optical path of incident light upward,
A current is caused to flow through the outer peripheral coil 212 in the direction shown in FIG. Due to the electromagnetic action of the magnetic field generated by the magnet 220 and the current of the outer peripheral coil 212, a force f is applied to the outer peripheral coil 212 in a direction perpendicular to the magnetic flux lines (indicated by arrows in the drawing). Here, since the outer peripheral coil 212 is fixed to the mirror holding portion (FIG. 8), the magnet 220 receives a force F, which is the same as f, but in the opposite direction, and swings counterclockwise in the figure. This F is the swing axis R
, The mirror frame 205 can be smoothly swung.

In order to stop the mirror frame 205 at a predetermined angle, a pair of magnetic pieces 23
2,234 are provided. When the S pole of the magnet 220 attracts the lower magnetic piece 234, the mirror frame 205
Stops at the position shown in FIG. 9 (c). The position of the magnetic piece 234 is set so that the mirror frame 205 stops at a predetermined upward angle (that is, the angle at which the deflecting mirror 26 deflects incident light toward the upper rotation arm 3a). Thus, the laser beam 13 incident on the deflecting mirror 26 can be deflected upward and guided to the upper rotating arm 3a.

In the state shown in FIG.
5 is further finely moved in the counterclockwise direction.
As shown in (d), a current in a direction opposite to that of the outer coil 212 flows through the inner coil 214. When the mirror frame 205 is finely moved clockwise in the state of FIG. 9C, a current in the same direction as the outer coil 212 is applied to the inner coil 2.
Pour into 14. Thereby, the deflection mirror 26 is moved to the position shown in FIG.
Fine tracking control can be performed by finely moving clockwise and counterclockwise around the position shown in (c).

When switching the optical path of the incident light downward,
A current in the opposite direction to that of FIG. As a result, as shown in FIG. 9E, the magnet 220 receives the force indicated by F in the figure and swings counterclockwise in the figure due to the electromagnetic action of the current and the magnetic field of the outer peripheral coil 212. When the magnet 220 swings to the state shown in FIG. 9F, the N pole of the magnet 220 attracts the upper magnetic piece 232, and the mirror frame 205 stops in the state shown in FIG. 9F.
The position of the magnetic piece 232 is set such that the mirror frame 205 stops at a predetermined downward angle (that is, the angle at which the deflecting mirror 26 deflects incident light toward the lower rotation arm 3b). Thus, the laser beam 13 incident on the deflection mirror 26 can be deflected downward and guided to the lower rotating arm 3b.

The fine tracking control in a state where the deflecting mirror 26 deflects the incident light downward is shown in FIG.
(The direction of the current flowing through each coil is reversed), and the description is omitted.

As described above, according to the optical disk device of this embodiment, one fixed optical unit 4 can be shared by a pair of rotating arms 3a and 3b. Therefore, the entire configuration of the optical head 100 can be simplified as compared with a case where all necessary optical systems are mounted on both the rotating arms 3a and 3b. In addition, the weight of the rotating arm, which is a movable part, can be reduced.

[0037]

As described above, according to the optical head of the optical disk apparatus of the present invention, a pair of rotating arms can share one fixed optical unit. Therefore, the entire configuration of the optical head can be simplified as compared with the case where all the necessary optical systems are mounted on both the rotating arms. In addition, the weight of the rotating arm, which is a movable part, can be reduced.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an optical disk device according to a first embodiment.

FIG. 2 is a side view showing a distal end portion of a rotating arm.

FIG. 3 is a side view showing a floating optical unit.

FIG. 4 is a plan view showing an optical head.

FIG. 5 is a side sectional view showing an optical head.

FIG. 6 is a diagram showing an optical system of the optical head.

FIG. 7 is a perspective view showing a configuration for swinging a deflecting mirror.

FIG. 8 is an exploded perspective view showing a configuration for swinging a deflecting mirror.

FIG. 9 is a schematic diagram showing a swinging method of a deflecting mirror.

[Explanation of symbols]

 2 Optical Disk 3a, 3b Rotating Arm 4 Fixed Optical Unit 6 Floating Optical Unit 26 First Deflection Mirror 35 Second Deflection Mirror 31 Third Deflection Mirror 42 Housing 55 Connection Arm 100 Optical Head 200 Mirror Holder 220 Magnet 210 Coil

Claims (8)

[Claims] 1. An optical disk device, comprising: an objective lens for converging a light beam on a recording surface of the optical disk, held rotatably about a common rotation axis, and rotated along both surfaces of the optical disk. A fixed optical unit fixed to a main body of the optical disc device, and a light beam from the fixed optical unit, one of the pair of rotating arms. An optical head for an optical disc device, comprising: a selection unit for selectively guiding the light beam from the fixed optical unit to the first optical unit; 2. The optical head according to claim 1, wherein the fixed optical unit further includes a light receiving unit that receives a light beam reflected from the recording surface. 3. The optical head according to claim 1, wherein the fixed optical system is located between the pair of rotating arms in the direction of the rotation axis. 4. The fixing means includes a first deflecting mirror for deflecting a light beam in the direction of the rotation axis in the fixed optical unit, and the optical axis deflected by the first deflecting mirror is rotated. 4. The optical head according to claim 1, wherein the optical head coincides with the axis. 5. The optical head according to claim 4, wherein the pair of rotating arms are switched by changing the direction of the first deflecting mirror. 6. The first deflecting mirror is a galvano mirror which performs fine tracking by finely adjusting an incident angle of a light beam to the objective lens by swinging about a predetermined axis on the mirror surface. 6. The optical head for an optical disk device according to claim 4, wherein the optical head is provided. 7. The rotating arm has at least two lenses between the first deflecting mirror and the objective lens, and the two lenses are arranged such that a swing axis of the deflecting mirror and the objective lens The entrance pupil of the lens has a conjugate relationship, and the mirror surface of the first deflecting mirror and the light beam incident on the entrance pupil surface of the objective lens are both determined to be parallel light, An optical head for an optical disk device according to claim 4. 8. The deflecting means includes a second deflecting mirror provided at a rotation axis position of each of the rotation arms.
The optical head of an optical disk device according to any one of claims 4 to 7, wherein: