JPH11149660A - Optical information recording and reproducing head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the change of the angle of incidence of an incident luminous flux on an objective optical system even when a deflection mirror supporting member is deformed by an external stress by respectively making the surface of one side and the surface of other side of two surfaces orthogonally crossing with each other of a penta prism to be utilized as a deflection mirror the incident surface and the light-emitting surface of a laser beam. SOLUTION: A deflection prism 31 is made a penta prism and the surface of one side and the surface of other side of two surfaces orthogonally crossing with each other of the mirror 31 are respectively made an incident surface 311 and a light-emitting surface 312 and two surfaces whose crossing angles are 45 degrees are made reflection surfaces 313, 314 and the mirror 31 is fixed to the inner wall of a rotating arm. Then, a laser luminous flux 13 from a polarizing mirror is made incident on the incident plane 311 and it is reflected on the reflection surfaces 314, 313 and then it is emitted from the light-emitting surface 312 to be made incident on the floating type optical unit 6 being in the downward direction. Here, since the prism 31 is made the penta prism, even when the angle of incidence of the incident laser lumonous flux on the mirror is changed by the deformation of the rotating arm to which the prism 31 is fixed or the like, the change of the angle of incidence θ of the incident laser luminous flux on the unit 6 is suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information recording / reproducing head, and more particularly to a head suitable for a head for deflecting a laser beam and performing fine movement tracking of an optical disk.

[0002]

BACKGROUND OF THE INVENTION Recently, a magneto-optical disk drive having a surface recording density exceeding 10 Gbit / (inch) ² has been developed. In this apparatus, the angle of incidence of a laser beam on an objective optical system provided at the end of a coarse movement arm that rotates, for example, in a direction intersecting the track of the magneto-optical disk is finely adjusted by a deflecting means such as a galvanometer mirror. It is considered that tracking is accurately performed at a narrow track pitch level of, for example, 0.34 μm. By the way, in such a coarse movement arm, the laser beam is guided by a deflecting mirror in a direction perpendicular to the optical disk immediately before being guided in a direction parallel to the optical disk via a deflecting means and made incident on the objective optical system, and then the objective optical system However, when the member supporting the deflecting mirror is deformed by external stress, there is a problem that the incident angle of the light beam incident on the objective optical system changes. .

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above background, and the invention of claim 1 is to convert a light beam emitted from a laser light source into a parallel light beam and then deflect the light beam. Optical information recording / reproduction in which a laser beam is deflected by a deflecting mirror in a direction perpendicular to the optical disk immediately before being guided into a direction parallel to the optical disk via the means and incident on the objective optical system, and then condensed on the optical disk by the objective optical system A head, wherein a pentaprism is used as the deflecting mirror, one of two surfaces of the pentaprism orthogonal to each other is a surface on which the laser beam from the polarizing means is incident, and the other surface is an emission surface. It is characterized by.

[0004]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, near-field recording (NFR: near field recording) has been proposed in response to a demand for an external storage device accompanying the recent advancement of hardware and software related to a computer, especially a demand for a large storage capacity. field recordin
g) An outline of a magneto-optical disk recording / reproducing apparatus using a recording / reproducing method called a technique will be described with reference to FIGS.

FIG. 1 is an overall schematic diagram of the optical disk device. An optical disk 2 is mounted on a rotating shaft of a spindle motor (not shown) in the disk drive device 1. On the other hand, a rotating (coarse movement) arm 3 for reproducing or recording information on the optical disk 2 is mounted so as to be parallel to the recording surface of the optical disk 2. This rotating arm 3
Is rotatable about a rotation shaft 5 by a voice coil motor 4. A floating optical head 6 having an optical element mounted thereon is mounted on a tip of the rotating arm 3 facing the optical disk 2. In addition, the rotating arm 3
A light source module 7 having a light source unit and a light receiving unit is disposed in the vicinity of the rotation shaft 5 and is configured to be driven integrally with the rotating arm 3.

FIGS. 2 and 3 illustrate the distal end portion of the rotating arm 3, and particularly illustrate the floating optical head 6 in detail. 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, and presses the floating optical unit 6 at the distal end portion in a direction in which the floating optical unit 6 comes into contact with the optical disc 2 by the elastic force of the flexure beam 8.

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 functions to converge a parallel laser beam 13 emitted from the light source module 7 onto the optical disc 2. A deflection prism 31 is fixed to the tip of the rotating arm 3 to guide the laser beam 13 to the floating optical unit 6. The laser beam 13 incident on the objective lens 10 by the deflection prism 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 in a magneto-optical recording system 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.

The light source module 7 mounted on the rotating arm 3 and the light beam guided to the floating optical unit 6 will be described in detail below with reference to FIGS. The rotating arm 3 has a floating type optical unit 6 mounted at the tip and a driving coil 1 for driving a voice coil motor 4 at the other end.
6 is fixed. The drive coil 16 is a flat coil, and is inserted and arranged in a magnetic circuit (not shown) with a gap. The rotating shaft 5 and the rotating arm 3 are provided with a bearing 17,
When the current is applied to the drive coil, the rotation arm 3 can be rotated about the rotation shaft 5 by the electromagnetic action with the magnetic circuit.

The light source module 7 mounted on the rotating arm 3 has a semiconductor laser 18, a laser drive circuit 19,
Collimating lens 20, composite prism assay 21, laser power monitor sensor 22, reflection prism 2
3, a data detection sensor 24 and a tracking detection sensor 25 are arranged. The laser beam in a divergent beam state 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 light beam onto the optical disk 2 minutely. Therefore, the cross-sectional shape of the parallel light beam is shaped by making the parallel light beam having an elliptical cross section emitted from the collimating lens 20 enter the composite prism assay 21.

The entrance surface 21a of the composite prism assay 21
Has a predetermined slope with respect to the incident optical axis. By refracting the incident light, the cross-sectional shape of the parallel light beam can be shaped from an oval shape to a substantially circular shape. The shaped laser beam travels through the complex prism assay 21 and enters the first half mirror surface 21b. The first half mirror surface 21b transmits information obtained from the optical disk 2 to the data detection sensor 24 and the tracking detection sensor 25.
However, on the outward path, it serves to separate the light beam to the laser power monitor sensor 22 for detecting the output power of the laser emitted from the semiconductor laser 18.

Since the laser power monitor sensor 22 outputs a current proportional to the intensity of the received light, the output of the semiconductor laser 18 can be stabilized by feeding back this output to a laser power control circuit (not shown). . The laser beam 13 having a substantially circular cross-sectional shape and emitted from the composite prism assay 21 is applied to the deflecting mirror 26, and the traveling direction of the laser beam 13 is changed. The deflecting mirror 26 is attached to a galvano motor 27 having a rotation center about an axis perpendicular to the plane of the paper, and can deflect the laser beam 13 by a small angle in a direction parallel to the plane of the paper.

The galvano motor 27 is provided with a deflection mirror position detection sensor 28 for detecting the rotation angle of the deflection mirror 26. The laser beam 13 reflected by the deflecting mirror 26 is transmitted to the first relay lens 29 and the second relay lens 29.
After passing through the relay lens (imaging lens) 30, the light is reflected by the deflecting prism 31, and then reaches the floating optical unit 6. The first relay lens 29 and the second relay lens 30 make the relationship between the reflection surface of the deflecting mirror 26 and the pupil surface (principal plane) of the objective lens 10 arranged in the floating optical unit 6 into a conjugate relationship. That is, a relay lens optical system is formed. That is, when the condensed beam on the optical disk 2 is slightly deviated from a predetermined track, the deflecting mirror 26 is slightly rotated to tilt the laser beam 13 incident on the objective lens 10 to move the focal point on the optical disk 2. Correction. However, when performing focus correction with this method,
If the optical distance between the deflecting mirror 26 and the objective lens 10 is long, the amount of movement of the laser beam 13 incident on the objective lens 10 increases, and it may not be possible to enter the objective lens 10.

In order to avoid such a phenomenon, the first relay lens 29 and the second relay lens 30
The relationship between the reflection surface of the deflecting mirror 26 and the pupil surface of the objective lens 10 is set to be a conjugate relationship, and even if the deflecting mirror 26 rotates, the laser beam 13 incident on the objective lens 10 does not move, Tracking control is made possible. The access operation over the inner circumference / outer circumference of the optical disk 2 is performed by rotating the rotating arm 3 by the voice coil motor 4, and only minute tracking control is performed by rotating the deflection mirror 26.

The return laser beam 13 reflected from the optical disk 2 and returning returns to the deflecting mirror 2 in a direction opposite to the forward path.
The reflected light is incident on the composite prism assay 21.
Thereafter, the light is reflected by the first half mirror surface 21b and travels to the second half mirror surface 21c. The second half mirror surface 21c generates transmitted light directed to the tracking detection sensor 25 and reflected light directed to the data detection sensor 24, and separates the laser beam on the return path. The laser beam transmitted through the second half mirror surface 21c is applied to the tracking detection sensor 25, and outputs a tracking error signal.

On the other hand, the laser beam reflected by the second half mirror surface 21c is polarized and separated by the Wollaston prism 32, converted into convergent light by the condensing lens 33, and then reflected by the reflecting prism 23 to be detected by the data detection sensor. 24. The data detection sensor 24 has two light receiving areas, and receives two polarized beams polarized and separated by the Wollaston prism 32 to read data information recorded on the optical disk 2 and output a data signal. 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 deflecting prism 31 in the above-mentioned rotating arm 3 will be described. FIG. 6 shows the deflection prism 3
FIG. The deflecting prism 31 is a pentaprism, and one of two surfaces orthogonal to each other is defined as an incident surface 311 and the other surface is defined as an emission surface 312. Further, two surfaces having an intersection angle of 45 ° are reflection surfaces 313 and 314. The deflecting prism 31 has a surface on the near side or the far side in FIG.
Is attached to the rotating arm 3.

The laser beam 1 from the above-described deflection mirror 26
Numeral 3 enters the incident surface 311, is reflected by the reflecting surfaces 313 and 314, exits from the exit surface 312, and enters the floating optical unit 6 located below.

As described above, since the deflecting prism 31 is configured as a pentaprism, even when the incident angle of the laser beam incident on the deflecting prism 31 changes due to deformation of the rotating arm 3 or the like, the floating type optical unit 6 can be used. Can be suppressed from changing the incident angle θ.

[0020]

As described above, according to the optical information recording / reproducing head of the present invention, even when the member supporting the deflecting mirror is deformed due to external stress, the incident angle of the light beam incident on the objective optical system is improved. Changes can be suppressed.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a basic configuration of a magneto-optical disk device according to an embodiment.

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

FIG. 3 is a cross-sectional view showing a floating optical unit.

FIG. 4 is a plan view showing a deflection mirror and a floating optical unit.

FIG. 5 is a side sectional view of a rotating arm.

FIG. 6 is a view showing a deflection prism.

[Explanation of symbols]

 3 rotating arm 31 deflection prism 311 entrance surface 312 exit surface

Claims (1)

[Claims] A light beam emitted from a laser light source is converted into a parallel light beam, and then guided in a direction parallel to the optical disk via a deflecting means to deflect the laser light beam in a direction perpendicular to the optical disk immediately before being incident on an objective optical system. An optical information recording / reproducing head which is deflected by a mirror and then condensed on an optical disk by the objective optical system.
An optical information recording / reproducing head, wherein one of the two surfaces is a surface on which the laser beam from the polarizing means is incident, and the other surface is an emission surface.