JP3097316B2 - Optical pickup - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a split optical pickup used for an optical video disk, a compact disk, a magneto-optical disk and the like.

[0002]

2. Description of the Related Art A conventional optical pickup will be described below with reference to the drawings.

FIGS. 5 and 6 show the structure of a typical conventional separation optical type optical pickup. Information is recorded on the optical disk 21, and this information is detected by an optical unit 22 including a laser light source and an optical sensor. The optical unit 22 is mounted on a carriage 23, and the carriage 23 is disposed so as to be movable in the tracking direction of the optical disk 21, and performs rough positioning. The carriage 23 is equipped with a prism-shaped reflecting mirror 24, a shaft 25 perpendicular to the carriage 23, and magnets 26 and 27. An objective lens 29, a focus coil 30 and a tracking coil 31 are mounted on the objective lens holder 28, and are supported by a shaft 25.

[0004] off among the magnetic field magnet 26 is generated
When the focusing coil 30 is energized, an electromagnetic force is generated in the axial direction of the shaft 25 according to Fleming's left-hand rule .
In addition, tracking in the magnetic field generated by the magnet 27
In the circumferential direction of the shaft 25 by energizing the Gukoiru 31
Generates electromagnetic force according to Fleming's left-hand rule . The objective lens holder 28 slides in the axial direction by these two forces to perform a focusing operation, and also rotates around an axis to perform a tracking operation to keep the objective lens at a predetermined position.

The laser beam 32 emitted from the optical section 22
Is condensed on the optical disk 21 via the reflection mirror 24 and the objective lens 29. The laser beam 32 reflected on the surface of the optical disk 21 returns along the same optical path, is converted into an electric signal by the optical unit 22, and is output as a position error signal and an information output signal.

It is necessary to control the position of the objective lens 29 so that the laser beam 32 is always focused on the optical disk 21. Therefore, based on the position error signal output from the optical unit 22, the focus coil 30 and the tracking coil 3
1 is controlled.

FIGS. 7 and 8 show the structure of the optical pickup as viewed from the direction of the optical section 22. FIG. The objective lens holder 28 is used for stopping the optical disk 21 and for inserting the optical disk.
In order to avoid contact with the reflection mirror, as shown in FIG. In operation, as shown in FIG. 8, the optical disk 21 is configured to follow a vertical shake while keeping a constant distance.

[0008]

In recent years, there has been an increasing demand for higher speed and thinner optical disk recording / reproducing devices, and higher speed and thinner optical pickups have been required. However, in the conventional optical pickup as described above, the carriage 23
As shown in FIG. 7, the distance from the optical disk 21 to the optical disk 21 is determined by the height when the apparatus is stopped and when the optical disk is inserted. That is, the height required is the sum of the height H1 of the reflection mirror 24, the height H2 of the objective lens holder 28, and the clearance H3 required when the optical disk 21 is inserted. Reducing the height enables a reduction in thickness. However, the height H1 of the reflection mirror 24 is a height including the minimum necessary light beam diameter of the laser beam and the edge sag that always occurs when processing the mirror surface, and it is difficult to reduce this height.
If the height H2 of the objective lens holder 28 is reduced, the rigidity of the objective lens holder is reduced and the resonance frequency is lowered, so that the access time cannot be shortened. The driving force required to move cannot be obtained. Therefore, it is difficult to reduce the height H2.

If the escape H3 from the optical disk is reduced, the optical disk can be brought closer to the optical pickup.
The height from the carriage 23 to the optical disk can be reduced. However, since the height when the apparatus is stopped is small, the height from the carriage 23 to the optical disk 21 is determined by the height during operation. That is, the height H1 of the reflection mirror 24, the height H2 of the objective lens holder 28, and the offset height H4 are required at the distance between the optical disk 21 and the objective lens 29. This offset height H4 is for the optical pickup to approach the optical disk during operation, and can be reduced if H3 can be reduced. However, the escape H3 from the optical disk needs to have a certain size as long as the optical disk specified by the standard is used, so that it cannot be reduced further. Therefore, the height of the conventional optical pickup is determined by the height at the time of stop, and the height cannot be reduced.

Due to these problems, it has been extremely difficult to realize a high-speed and thin optical pickup having a small distance from the carriage to the optical disk.

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical pickup which has a small distance from a carriage to a recording surface of an optical disk, is thin, and can be accessed at high speed.

[0012]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has an objective lens for condensing laser light on an optical disk, an objective lens holder, and an optical element for emitting laser light and detecting return light. parts and the optical path from the optical unit have a configuration and an optical element for guiding the objective lens, the line tracking operation accommodating the reflection mirror to the objective lens holder
A hole that does not touch even if it stops, the objective lens holder can be moved to a position that blocks the optical path from the optical unit when stopped
An optical pickup characterized in that:

[0013]

According to this structure, when the objective lens holder is retracted, it can be retracted to a position where it blocks the optical path from the fixed optical unit, and can be driven at a position lower than the conventional one without interrupting the optical path in the normal driving state.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An optical pickup according to an embodiment of the present invention will be described below with reference to the drawings, taking a separated optical pickup as an example. FIG. 1 shows the configuration of the optical pickup viewed from the optical disk 1 side.

[0015] Information is recorded on an optical disk 1, and this information is detected by an optical unit 2 comprising a laser light source, an optical sensor and the like. The optical section 2 is mounted on a carriage 3, and the carriage 3 is disposed movably in the tracking direction of the optical disc 1, and performs rough positioning. The carriage 3 is equipped with a prism-shaped reflecting mirror 4, a shaft 5 provided perpendicular to the carriage 3, and magnets 6 and 7. An objective lens 9, a focus coil 10 and a tracking coil 1 are mounted on the objective lens holder 8, and are supported by the shaft 5. Further, the reflecting mirror 4 enters the reflecting mirror side of the objective lens holder 8,
Further, a hole 12 is formed such that the objective lens holder 8 does not come into contact with the reflection mirror 4 even when the tracking operation is performed.

In the magnetic field generated by the magnet 6 ,
When the coil 10 is energized , the
Generates electromagnetic force according to Fleming's left-hand rule . In addition, the tracking coil in the magnetic field generated by the magnet 7
Fleming around the axis of shaft 5 by energizing
Generates an electromagnetic force according to the left hand rule . The objective lens holder 8 slides in the axial direction by these two forces to perform a focusing operation, rotates around the axis to perform a tracking operation, and keeps the objective lens 9 at a predetermined position.

The laser beam 13 emitted from the optical section 2 is focused on the optical disk 1 via the reflection mirror 4 and the objective lens 9. The laser light reflected by the optical disk 1 returns along the same optical path, is converted into an electric signal by the fixed optical unit 2, and is output as a position error signal and an information signal.

It is necessary to control the position of the objective lens 9 so that the laser light 13 is always focused on the optical disk 1. Therefore, based on the position error signal output from the optical unit 2, the focus coil 10 and the tracking coil 11
To control the current flowing through it.

FIGS. 3 and 4 show the structure of the optical pickup viewed from the direction of the optical section 2. FIG. The object lens holder 8 is retracted to a position where the reflection mirror 4 enters the hole 12 as shown in FIG. At this time, the objective lens holder 8 blocks the optical path connecting the fixed optical unit 2 and the reflection mirror 4 as shown in FIG. During operation, the objective lens holder 8 performs a focusing operation within a certain range as shown in FIG. In the most retracted state during normal operation, that is, when approaching the reflection mirror, the objective lens holder moves to a position that overlaps the reflection mirror and does not block the optical path.

As shown in FIG. 3, the height from the carriage 3 to the optical disk 1 is the height H5 of the reflecting mirror 4 and the objective lens holder 8, and the clearance H3 required when the disk is inserted into the disk.
Is determined by Naturally, since H5 <H1 + H2, the optical pickup of this embodiment can be made thinner by ΔH = H5- (H1 + H2) than the conventional optical pickup.

Since H5 can be made sufficiently small by the above configuration, the height from the carriage 3 to the optical disk 1 in this embodiment is determined by the height during operation. However, unlike the conventional optical pickup, the objective lens holder 8 can be covered by the reflection mirror 4, so that the lower limit position can be lowered to the surface droop generated at the time of processing the upper end of the reflection mirror 4. That is, the height obtained by adding the height H2 of the objective lens holder 8 to the distance between the optical disc 1 and the objective lens 9 and the height H6 from the carriage 3 to the upper end of the light beam of the laser beam 12 is from the carriage 3 to the optical disc 1. Of height.
This height is smaller than the height of the conventional optical pickup in operation except for the offset height H4.

According to the above configuration, a thin optical pickup can be realized. In this embodiment, the configuration using the reflection mirror has been described. However, an optical member such as a prism may be used instead of the reflection mirror. Also, the reflecting mirror does not need to be particularly prism-shaped, and a flat mirror may be used. Even if a prism-shaped reflecting mirror is used, the same effect can be obtained even if the shape is cylindrical.

[0023]

As is apparent from the above description of the embodiment, according to the present invention, an objective lens for condensing a laser beam on an optical disk, an objective lens holder, a laser beam is emitted, and An optical unit for detecting return light and an optical element for guiding an optical path from the optical unit to the objective lens are provided, and the objective lens holder moves to a position where the optical path from the optical unit is blocked. With this configuration, it is possible to provide a thin optical pickup that can be accessed at high speed.

[Brief description of the drawings]

FIG. 1 is a plan view showing a schematic configuration of an optical pickup according to an embodiment of the present invention.

FIG. 2 is a front sectional view of the same.

FIG. 3 is a side sectional view of the same.

FIG. 4 is a side sectional view showing the same operation state.

FIG. 5 is a plan view showing a schematic configuration of a conventional optical pickup.

FIG. 6 is a front sectional view of the same.

FIG. 7 is a side sectional view of the same.

FIG. 8 is a side sectional view showing the same operation state.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical disk 2 Optical part 3 Carriage 4 Reflection mirror 8 Object lens holder 9 Object lens 12 Hole 13 Laser light

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-193326 (JP, A) JP-A 2-68325 (JP, U) JP-A 62-3626 (JP, U) (58) Investigation Field (Int.Cl. ⁷ , DB name) G11B ^7/ 08-7/22

Claims (1)

(57) [Claims] 1. An objective lens for condensing a laser beam on an optical disc, an objective lens holder, an optical unit for emitting a laser beam and detecting return light, and an optical path for guiding an optical path from the optical unit to the objective lens. a structure and a device, housed tracking moving the reflecting mirror to the objective lens holder
Provide a hole that does not come into contact even when performing operations, and when stopped, move to a position where the objective lens holder blocks the optical path from the optical unit
An optical pickup characterized in that it can be configured .