JP2706548B2 - Separate optical head for optical disk drive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] A separation type optical head used in an optical disc device in which a movable section including an objective lens is separated from a fixed section including a light source section, and an object thereof is to enable a reduction in thickness. A fixing unit having a light source unit for emitting laser light, a galvanomirror for oscillating the laser light for tracking control, and a galvanomirror driving mechanism; an objective lens for condensing the laser light as a spot on an optical disc; and focus control. An objective lens driving mechanism for driving the objective lens, a flip-up mirror for reflecting laser light from the fixed portion so as to be incident on the objective lens,
In a separation type optical head of an optical disc device, comprising a movable part which is separated from the fixed part and moves in a radial direction of the optical disk, an optical axis of the laser beam directed from the fixed part to the movable part is a Z-axis. In a three-dimensional coordinate system in which the horizontal axis in the plane perpendicular to the Z axis is the X axis and the axis in the vertical direction is the Y axis, the galvanomirror is rotated in the XZ plane. The driving mechanism is disposed on the XY plane, and the laser light traveling from the fixed part to the movable part is swung in the XZ plane. Assuming that the X-ray direction component of the slope normal vector is i _X , the Y-axis direction component is j _Y , and the Z-axis direction component is k _Z , j _Y = k _Z and i _{X 、} 0 ,
The movement of the spot on the optical disk according to the deflection of the laser beam on the XZ inner surface has a component in a direction crossing a track on the optical disk.

[Detailed description of the invention]

The present invention relates to a separation type optical head used for an optical disc device in which a movable section including an objective lens is separated from a fixed section including a light source section.

With an increase in the density of optical disk information recording, a fast access time is required for an optical head.

For the purpose of speeding up access, a separation type optical head 1 shown in FIG. 2 has been proposed.

Reference numeral 2 denotes a fixing unit having a semiconductor laser 3 and the like, which is fixed to a chassis 5 of the optical disc device 4.

Reference numeral 6 denotes a movable portion, which includes a flip-up mirror 7, an objective lens 8, and the like, and is movable in the radial direction of the optical disk 9 as shown by an arrow A.

The fixed part 2 and the movable part 6 are connected by a laser beam 10.

In order to speed up the access, it is necessary to reduce the weight of the movable part 6.

Further, it is desired to make the optical disk device thinner.

For this purpose, the optical head needs to have a thin structure.

In the above-mentioned separation type optical head, the movable portion 6 is small, and the thickness of the movable portion 6 is determined by the fixed portion 2.

For this reason, it is necessary to make the fixing part 2 as thin as possible.

[Conventional technology]

Japanese Patent Application Laid-Open No. 1-150233 discloses a separation type optical head 20 shown in FIG. In the figure, parts corresponding to those shown in FIG. 2 are denoted by the same reference numerals.

The optical head 20 is provided with only the focus direction actuator 21 without the focus direction actuator and the focus direction actuator among the focus direction actuator and the tracking direction actuator which are originally required for the objective lens 8, and the tracking direction actuator 22 is fixed to the fixed part. 23.

The movable section 24 is reduced in weight by the weight of the tracking direction actuator, thereby achieving high-speed access.

The tracking direction actuator 22 has a configuration in which the carbano mirror 25 is supported by a horizontal shaft 26, and the carbano mirror 25 is rotated in a vertical plane by an electromagnetic drive mechanism 27 as shown by an arrow B.

Laser light 28 from semiconductor laser 3 is carbano mirror 25
The laser light 29 is reflected by the flip-up mirror 7 to be directed toward the flip-up mirror 7, and is reflected by the flip-up mirror 7 to be a laser light 30 directed directly upward. This laser light 30 passes through the objective lens 8 and
The light is condensed on the optical disk 9 to form a spot 31.

When the carbano mirror 25 is rotated, the flip-up mirror 7
The laser beam 29 heading toward the center oscillates in the vertical plane as shown by the two-dot chain line, and the spot 31
Move in the radial direction of the optical disk 9 indicated by, that is, in the direction crossing the track 33. Thus, tracking control is performed.

[Problems to be solved by the invention]

The carbano mirror 25 is supported by a horizontal shaft 26, and its rotating surface is in a vertical plane. Therefore, the electromagnetic driving mechanism 27 is provided in a vertical type.

The electromagnetic driving mechanism 27 are disposed in a vertical, a tracking direction actuator 22 is bulky in the height direction, the fixing portion 23 and the height dimension t ₁ becomes large, the separation type optical head 20 to be a thin It was difficult.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a separation type optical head of an optical disk device that can be made thin.

[Means for solving the problem]

The present invention provides a light source unit that emits a laser beam and a fixed unit having a galvanomirror and a galvanomirror driving mechanism that oscillates the laser beam for tracking control.An objective lens that condenses the laser beam as a spot on an optical disc, An objective lens driving mechanism for driving the objective lens for focus control, a flip-up mirror for reflecting laser light from the fixed portion so as to be incident on the objective lens, and being separated from the fixed portion; In the separation type optical head of the optical disk device including a movable portion that moves in a radial direction of the optical disk, the optical axis of the laser beam from the fixed portion to the movable portion is set to Z.
Axis, the horizontal axis in a plane perpendicular to the Z axis is the X axis,
In a three-dimensional coordinate system having a vertical axis as a Y axis, the galvanomirror is provided so as to rotate in an XZ plane, and the driving mechanism is disposed on the XZ plane.
The laser light traveling from the fixed part toward the movable part is X-
The flip-up mirror is arranged so that the X-ray component of the normal vector of the reflecting surface is i _X , the Y-axis component is j _Y , and the Z-axis component is
In case of the K _Z, j _Y = a k _Z, and i determined to _X ≠ 0 orientation, the movement of the spot on the optical disk in accordance with the deflection of the laser beam in the X-Z inner surface of the above said It is configured to have a component crossing the track on the optical disc.

[Action]

Let the normal vector of the flip-up mirror be j _Y = k _Z , i _X ≠ 0
The direction of the movement is such that, even if the direction of the laser beam deflection coming from the fixed part to the movable part is on the XZ plane, the direction of the movement of the spot on the optical disc is the same as the direction having a component crossing the track. Become.

Thereby, the rotation plane of the carbano mirror can be an XZ plane.

Along with this, the driving mechanism is disposed on the XZ plane, and the fixing portion becomes thin.

〔Example〕

FIG. 1 shows a separation type optical head 40 according to an embodiment of the present invention.
Is shown.

In the figure, parts corresponding to those shown in FIG. 3 are denoted by the same reference numerals, and description thereof is omitted.

Reference numeral 41 denotes a fixed portion, which is fixed on a chassis (not shown).

Reference numeral 42 denotes a movable portion, which is indicated by an arrow A on a chassis (not shown).
Are moved in the radial direction of the optical disk 9 indicated by.

 The fixed portion 41 and the movable portion 42 are connected by a laser beam 43.

A flip-up mirror 44 is fixed to the movable part 42. The flip-up mirror 44 sets the optical axis of the laser light 43 to the Z axis,
X is the horizontal axis in a plane passing through the point 0 on the Z axis and perpendicular to the Z axis.
In the three-dimensional coordinates with the axis and the vertical axis as the Y axis, the normal vector 45 of the reflection surface 44a is defined by the above-mentioned point 0 as a reference point, and the components in each axis direction (i _X , J _Y , k _Z ) Is j _Y = k _Z and i _X ≠
The direction is fixed so as to face in the direction of 0.

The Z axis is the radial direction of the optical disc 9 and the X axis is the tangential direction of the track 33 of the optical disc 9.

Since j _Y = k _Z , the flip-up mirror 44 reflects the laser light coming in the Z-axis direction (on the XZ plane) in the Y-axis direction. Since i _X ≠ 0, the movement trajectory 47 of the spot 46 on the optical disk 9 is kept in the longitudinal direction of the track 33 (X-axis direction) even when the laser beam 43 is swung on the XZ plane, as described later. ), A displacement component in the direction crossing the track 33 (the direction of the line 32) is obtained, and tracking control becomes possible.

In the fixed part 41, 50 is a tracking direction actuator, and the carbano mirror 51 is a vertical axis 52 parallel to the Y axis.
And is rotatably provided in the direction of arrow C in the XZ plane (horizontal plane). Reference numeral 53 denotes an electromagnetic drive mechanism, which is provided horizontally on the XZ plane (horizontal plane).

The carbano mirror 51 is rotated in the XY plane by the electromagnetic driving mechanism 53.

Laser light 60 emitted from the semiconductor laser 3 passes through a collimator lens 61 and a beam splitter 62, and a carbano mirror 51
, And is reflected here and becomes a laser beam 43 toward a flip-up mirror 44.

The laser light 43 is reflected at a point 63 on the flip-up mirror 44, becomes a laser light 64, and travels directly upward.

The laser beam 64 is focused through the objective lens 8 and forms a spot 46 on the optical disc 9.

When the galvanomirror 51 is rotated in the direction of arrow C, the laser beam 43 oscillates on the XZ plane (horizontal plane) as indicated by reference numerals 43a and 43b, for example.

The laser beam 43a is reflected right above the point 63a of the flip-up mirror 44, and travels directly above as a laser beam 64a.

The laser beam 43b is also reflected just above at the point 63b, and becomes a laser beam 64b and goes directly above.

Here, the direction of the flip-up mirror 44 is set to i _X ≠ as described above.
Since it is determined to be 0, the locus of the points 63, 63a, 63b when the laser beam 43 is swung in the XZ plane as described above
65 indicates an angle β with respect to the X axis. That is, the moving direction of the point 63 has a component in the Z direction. The laser beam 64a is applied to the objective lens 8
Passes the spot 46a on the optical disk 9 through the
6b also connects spot 46b.

Therefore, the movement trajectory 47 of the spot 46 has an angle α with respect to the X-axis direction, and a displacement component in a direction crossing the track 33 is obtained.

 This enables tracking control.

Further, the fixed portion 41 includes a half-wave plate 70 for obtaining a reproduction signal, a tracking control signal, and a focus control signal,
Polarizing beam splitter 71, condenser lenses 72, 73, photodetector 7
4,75 etc. are provided.

Here, since the rotating surface of the carbano mirror 51 is a horizontal plane, the electromagnetic drive mechanism 53 is placed horizontally, and can be arranged without being bulky in the height direction.

Therefore, the thickness of the fixing portion 41 is considerably thinner than the conventional case shown t ₂ becomes, in Figure 3.

Thereby, the separation type optical head 40 can be configured to be thinner than before, and ultimately, the optical disc device can be configured to be thinner than before.

The direction of the lift-up mirror 44 is not limited to the above embodiments, may be in a direction X-axis component of the normal vector 45 is -i _X.

〔The invention's effect〕

As described above, according to the present invention, the rotation surface of the carbano mirror can be set to XY depending on the direction of the flip-up mirror. As a result, the driving mechanism of the carbano mirror becomes X-
It is arranged on the Y surface, and the fixing portion can be configured to be thin.

As a result, the separation type optical head can be configured to be thin, and the thickness of the optical disk device can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a separation type optical head according to an embodiment of the present invention, FIG. 2 is a schematic configuration diagram of a general separation type optical head, and FIG. 3 is a schematic configuration of a conventional separation type optical head. FIG. In the figure, 3 is a semiconductor laser, 8 is an objective lens, 9 is an optical disk, 21 is a focus direction actuator, 32 is a line indicating the radial direction of the optical disk 9, 33 is a track, 40 is a detachable optical head, 41 is a fixed part, 42 is a movable part, 43, 60, 64 are laser beams, 44 is a flip-up mirror, 45 is a normal vector, 46 is a spot, 47 is a spot movement trajectory, 50 is a tracking direction actuator, 51 is a carbano mirror, and 52 is a vertical axis Numeral 53 indicates an electromagnetic drive mechanism, numeral 60 indicates a laser beam, numeral 63 indicates an incident (reflective) point, and numeral 65 indicates a locus of the point 63.

Claims (1)

(57) [Claims] A fixed portion having a light source section (3) for emitting a laser beam (43), a galvano mirror (51) for oscillating the laser beam (43) for tracking control, and a galvano mirror driving mechanism (53). 41) an objective lens (8) for condensing the laser beam as a spot (46) on the optical disc (9), an objective lens driving mechanism (21) for driving the objective lens (8) for focus control, A flip-up mirror (44) for reflecting the laser beam (43) from the fixed part (4) so as to be incident on the objective lens (8), separated from the fixed part, (9) In the separation type optical head of the optical disk device including the movable portion (42) moving in the radial direction (Z), the laser beam (43) directed from the fixed portion (41) to the movable portion (42). Optical axis is Z axis. In a three-dimensional coordinate system in which the horizontal axis in the vertical plane is the X axis and the vertical axis is the Y axis, the galvanomirror (51) is provided to rotate in the XZ plane; The drive mechanism (53) is disposed on the XZ plane, and the laser beam (43) traveling from the fixed section to the movable section is swung in the XZ plane. Let (44) be the component of the normal vector (45) of the reflection surface (44a) in the X-axis direction i _X and the component in the Y-axis direction
j _Y, the Z-axis direction component when the K _Z, j _Y = a k _Z, and determined the i _X ≠ 0 orientation, deflection of the laser beam (43) in the above X-Z plane Wherein the movement of the spot (46) on the optical disk according to the above has a component in a direction crossing the track (33) on the optical disk (9).