JPH03286431A - Separate type optical head for optical disk device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Summary] An object of the present invention is to enable thinning of a separate optical head used in an optical disc device, which is constructed by separating a movable part including an objective lens from a fixed part including a light source part. A light source unit that emits a laser beam, a fixed unit that has a galvano mirror and a galvano mirror drive mechanism that swing the laser beam for tracking control, an objective lens that focuses the laser beam as a spot on the optical disk, and a focus control unit. an objective lens drive mechanism for driving the objective lens; and a flip-up mirror for reflecting the laser beam from the fixed part so as to be incident on the objective lens, and is separated from the fixed part; In a separate optical head of an optical disk device comprising a movable part that moves in the radial direction of the optical disc, the optical axis of the laser beam directed from the fixed part to the movable part is the Z-axis, and the optical axis is defined as the Z-axis in a plane perpendicular to the Z-axis. In a three-dimensional coordinate system in which the horizontal axis is the X wheel and the vertical axis is the Y axis, the galvanomirror is provided to rotate within the X-2 plane, and the drive mechanism is rotated within the X-Y plane. The flip-up mirror is configured so that the laser beam directed from the fixed part toward the movable part is swung within the X-2 plane, and the flip-up mirror is configured such that the X-axis direction component of the normal vector of the reflecting surface is ix, where the Y-axis direction component is jv and the Z-axis direction component is kz, the direction is determined to be jv-kz and 1x4Q, and the above-mentioned direction is determined according to the deflection of the laser beam on the above-mentioned X-Z inner surface. The movement of the spot on the optical disc is configured to have a component in a direction across the tracks on the optical disc.

[Detailed description of the invention]

The present invention relates to a separate optical head used in an optical disc device, in which a movable part including an objective lens is separated from a fixed part including a light source part.

As the density of information recording on optical discs increases, optical heads are required to have faster access times.

A separate optical head 1 shown in FIG. 2 has been proposed for the purpose of speeding up access.

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

6 is a movable part, which includes a flip-up mirror 7 and an objective lens 8.
etc., and is movable in the radial direction of the optical disc 9, as shown by arrow A.

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

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

Furthermore, it is desired that optical disk devices be made thinner.

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

In the above separation type optical head, the movable part 6 is small, and the fixed part 2 determines its thickness.

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

[Conventional technology]

JP-A-1-150233 discloses a separate optical head 20 shown in FIG. 3. In the figure, parts corresponding to those shown in FIG. 2 are given the same reference numerals.

Of the focus direction actuator and tracking direction actuator that are originally required for the objective lens 8, this optical head 20 eliminates the tracking direction actuator and provides only the focus direction actuator 21.
2 is provided inside the fixing part 23.

The weight of the movable part 24 is reduced by 5 times the weight of the tracking direction actuator, and access speed is increased.

The tracking direction actuator 22 is configured to support the carbanomirror 25 by a horizontal shaft 26, and rotate the carbanomirror 25 in a vertical plane as shown by an arrow B using an electromagnetic drive mechanism 27.

The laser beam 28 from the semiconductor laser 3 is transmitted to the carbano mirror 2
Laser beam 29 reflected by 5 and directed toward flip-up mirror 7
The laser beam 30 is reflected by the flip-up mirror 7 and directed directly upward. This laser beam 30 is transmitted through the objective lens 8
, and is focused on the optical disk 9 to form a spot 31 .

When the carbanomirror 25 is rotated, the flip-up mirror 7
The laser beam 29 heading toward the direction swings in the vertical plane as shown by the two-dot chain line, and the spot 31 moves in the radial direction of the optical disc 9 shown by the line 32, that is, in the direction across the track 33, as shown by the symbols 31a and 31b. do. Tracking control is thereby performed.

[Problem to be solved by the invention]

Since the carbanomirror 25 is supported by a horizontal shaft 26 and its rotation plane is within a vertical plane, the electromagnetic drive mechanism 27 is provided vertically.

Since the electromagnetic drive mechanism 27 is arranged vertically, the tracking direction actuator 22 is bulky in the height direction, and the height dimension t1 of the fixed part 23 is large, which makes it difficult for the separation type optical head 2
It was difficult to make 0 thin.

SUMMARY OF THE INVENTION An object of the present invention is to provide a separate optical head for an optical disc device that can be made thinner.

[Means to solve the problem]

The present invention includes a light source unit that emits a laser beam, a fixing unit that includes a carbano mirror that swings the laser beam for tracking control, and a carbano mirror drive mechanism, an objective lens that focuses the laser beam as a spot on an optical disk, and a focus control unit. an objective lens drive mechanism for driving the objective lens; and a flip-up mirror that reflects the laser beam from the fixed part to the objective lens in a large sword manner, and is separated from the fixed part. , in a separate optical head of an optical disc device comprising a movable part that moves in the radial direction of the optical disc, the optical axis of the laser beam directed from the fixed part to the movable part is the Z axis, and the optical axis is in a plane perpendicular to the Z axis. In a three-dimensional coordinate system in which the horizontal axis is the X-axis and the vertical axis is the Y-axis, the force rubano mirror is provided to rotate within the x-2 plane, and the drive mechanism is connected to the x-2 plane. The laser beam directed from the fixed part to the movable part is directed to the x-Z plane.
If the above-mentioned flip-up mirror is configured to swing in a plane, and the X-axis direction component of the normal vector of the reflecting surface is i×, the Y-axis direction component is jy, and the Z-axis direction component is kz, then jv=
kz and 1x40, and the movement of the spot on the optical disk in response to the deflection of the laser beam on the x-Z inner surface has a component in the direction across the tracks on the optical disk. .

[Effect]

The normal vector of the flip-up mirror is 2,1x to jv=
40, even if the direction of the laser beam deflection entering the movable part from the fixed part is in the X-2 plane, the direction of movement of the spot on the optical disk is a direction that has a component in the direction across the track. becomes.

Thereby, the plane of rotation of the force levano mirror can be made into the X-2 plane.

Accordingly, the drive mechanism is disposed on the X-2 plane, and the fixing part becomes thin.

(Embodiment) FIG. 1 shows a separation type optical head 40 which is an embodiment of the present invention.
shows.

In the figure, parts corresponding to those shown in FIG. 3 are designated by the same reference numerals, and their explanations will be omitted.

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

42 is a movable part, which is moved by arrow A on the chassis (not shown).
The optical disc 90 is moved in the radial direction indicated by .

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

A flip-up mirror 44 is fixed to the movable part 42.

This flip-up mirror 44 has a three-dimensional structure in which the optical axis of the laser beam 43 is the Z axis, the horizontal axis is the X ring, and the vertical axis is the Y axis in a plane passing through the point O on the Z axis and perpendicular to the Z axis. In the original coordinates, the normal vector 45 of the reflective surface 44a uses the above point O as a reference point, and the components (ix, JY, kz) in each axis direction are as follows:
It is oriented and fixed so that it is jv-kz and faces in the 1x4Q direction.

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.

By being jv-kz, the flip-up mirror 44 is
Laser light entering in the direction of two wheels (on the X-2 plane) is reflected in the direction of seven wheels. ix to O, as will be described later, even when the laser beam 43 is swung on the A predetermined angle α is formed with respect to the track 33, and a displacement component in the direction across the track 33 (in the direction of the line 32) is obtained, making tracking control possible.

In the fixed part 41, 50 is a tracking direction actuator, in which a carbanomirror 51 is supported by a vertical shaft 52 parallel to the Y axis, and is provided so as to be rotatable in the direction of arrow C within the x-2 plane (horizontal plane). . 53 is an electromagnetic drive mechanism, which is installed horizontally on the X-2 plane (horizontal plane).

By the electromagnetic drive mechanism 53, the carbano mirror 51 is
rotated within the plane.

A laser beam 60 emitted from the semiconductor laser 3 passes through a collimating lens 61 and a beam splitter 62, reaches a carbanomirror 51, is reflected there, becomes a laser beam 43, and heads toward a flip-up mirror 44.

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

Laser light 64 is focused through objective lens 8 and forms a spot 46 on optical disc 9 .

When the galvanometer mirror 51 is rotated in the direction of arrow C, the laser beam 43 is emitted onto the
It swings as shown in 43b.

The laser beam 43a hits a point 63a on the flip-up mirror 44.
The laser beam 64a is reflected directly upward and becomes a laser beam 64a that heads directly upward.

The laser beam 43b is also reflected directly upward at the point 63b,
It becomes a laser beam 64b and heads directly upward.

Here, the orientation of the flip-up mirror 44 is 1x as described above.
40, the above point 63.63a when the laser beam 43 is swung within the x-1 plane as above.
, 63b shows an angle β with respect to the X axis. That is, the moving direction of point 63 also has a Z-direction component. The laser beam 64a passes through the objective lens 8 and forms a spot 46a on the optical disk 9, and the laser beam 46b similarly forms a spot 46b.
Tie.

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

This enables tracking control.

The fixed part 41 also includes a 172-wave plate 7 for obtaining reproduction signals, tracking control signals, and focus control signals.
0, polarizing beam splitter 71, condensing lens 72.73
, photodetectors 74, 75, etc. are provided.

Here, since the rotating surface of the carbanomirror 51 is a horizontal plane, the electromagnetic drive 11111i53 can be placed horizontally and can be arranged without being bulky in the height direction.

Therefore, the thickness of the fixing part 41 is t2, which is considerably thinner than the conventional one shown in FIG.

As a result, the separation type optical head 40 can be made thinner than in the past, and ultimately the optical disc device can be made thinner than in the past.

Note that the direction of the flip-up mirror 44 is not limited to that in the above embodiment, but may be a direction in which the X-axis component of the normal vector 45 is 11×.

[Effects of the Invention] As explained above, according to the present invention, the rotation plane of the carbano mirror can be set to the X-2 plane by the orientation of the flip-up mirror. This causes the carbano mirror drive mechanism to
It is arranged on two sides, and the fixing part can be configured to be thin.

As a result, the separation type optical head can be made thinner, and the optical disk device can be made thinner.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of a separate optical head according to an embodiment of the present invention, Fig. 2 is a schematic diagram of a general separated optical head, and Fig. 3 is a schematic diagram of a conventional separated optical head. It is a diagram. 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 separation type optical head, 41 is a fixed part, 42 is a movable part, 43, 60, 64 is a laser beam, 44 is a flip-up mirror 45 is a normal vector, 46 is a spot, 47 is a moving trajectory of the spot, 50 is a tracking direction actuator, 51 is a carbano mirror 52 is a vertical axis, 53 60 is an electromagnetic drive mechanism, 60 is a laser beam, 63 is an incident (reflection) point, and 65 is a locus of the point 63.

Claims (1)

[Claims] A light source unit (3) that emits a laser beam (43), a galvano mirror (51) that swings the laser beam (43) for tracking control, and a galvano mirror drive mechanism (53).
an objective lens (8) for focusing the laser beam as a spot (46) on the optical disk (9), and the objective lens (8) for focus control.
an objective lens drive mechanism (21) that drives the fixed part (
a flip-up mirror (44) that reflects the laser beam (43) from the optical disc (4) so that it enters the objective lens (8); In a separate optical head for an optical disk device that includes a movable part (42) that moves in the radial direction (Z), the optical axis of the laser beam (43) directed from the fixed part (41) to the movable part (42) is set in the Z direction. In a three-dimensional coordinate system in which the horizontal axis in a plane perpendicular to the Z axis is the X axis and the vertical axis is the Y axis, the galvanometer mirror (51) is rotated in the X-Z plane. The driving mechanism (53) is arranged on the X-Z plane, and the laser beam (43) directed from the fixed part toward the movable part is swung within the X-Z plane. The flip-up mirror (44) has a reflecting surface (44a)
When the X-axis direction component of the normal vector (45) is i_X, the Y-axis direction component is j_Y, and the Z-axis direction component is k_Z, set the direction so that j_Y=k_Z and i_X≠0, The movement of the spot (46) on the optical disk in response to the deflection of the laser beam (43) in the X-Z plane has a component in a direction that crosses the track (33) on the optical disk (9). A separate optical head for an optical disc device, characterized in that: