JPH05144067A - Optical head - Google Patents

Abstract

PURPOSE:To improve the yield by dividing light reception faces of photodetectors into various directions to surely receive a reflected light beam regardless of disorder of the form of a light branching means. CONSTITUTION:The light reception face of a photodetector 42 is divided into three in the direction orthogonal to the array direction of photodetectors 40, 42 in the same manner as a conventional micro prism detector, but that of the photodetector 40 is divided into three in the direction orthogonal to the dividing direction of the photodetector 42. Photodetectors 40, 42 are so formed that each divided light reception face is longer than a conventional photodetector, and thereby, the reflected light beam can be surely received even if the form of the prism is disordered. Consequently, the yield of the magneto-optical head is improved even if the working precision of the prism is low.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical head, and is particularly suitable for application to an optical head using a micro prism detector.

[0002]

2. Description of the Related Art Conventionally, as a magneto-optical disk device for thermo-magnetically recording desired information, a magneto-optical disk device has been proposed in which a light-emitting element and a light-receiving element are integrally integrated on a semiconductor substrate to form a magneto-optical head. (Japanese Patent Laid-Open No. 64-33734
Publication).

That is, in FIG. 8, reference numeral 1 denotes a magneto-optical head as a whole, which is a light beam LA emitted from the semiconductor laser 2.
After 1 is converted into parallel rays by the relay lens 4, it is focused on the magneto-optical disk 8 through the objective lens 6. At this time, in the magneto-optical head 1, a predetermined modulation magnetic field is applied to the focal position of the light beam LA1, so that desired recording information is thermomagnetically recorded according to the modulation magnetic field.

Further, in the magneto-optical head 1, a polarized beam splitter 1 is provided between the objective lens 6 and the relay lens 4.
0 is inserted to switch the light amount of the reproduction light beam LA1 and the polarization beam splitter 10 separates the reflected light beam LA2 of the magneto-optical disk 8. Further, in the magneto-optical head 1, the separated reflected light beam LA2 is halved.
The light is guided to the microprism contactor 16 via the wave plate 12 and the focusing lens 14.

Here, as shown in FIG. 9, the micro prism detector 16 is formed by laminating a triangular prism 16B on a parallelogram-shaped orthorhombic prism 16A having an inclined surface formed at an angle of 45 degrees. Then, a polarized beam splitter is formed at the joint surface M1 of the prisms 16A and 16B. Further, in the micro prism prism 16, the light receiving elements 18 and 20 are arranged so as to be in contact with the prisms 16A and 16B.
Of the reflected light beam LA2 incident from above toward the joint surface M1 of 6A and 16B, the transmitted light of the joint surface is incident on the light receiving element 18.

Here, as shown in FIG.
And 20, the semiconductor substrates 21 are arranged in a line.
The light receiving surface is integrally formed on the upper side, and the light receiving surface is divided into three in a direction orthogonal to the arrangement direction. On the other hand, in the light receiving element 20, the reflected light beam on the joint surface M1 is reflected by the prism 1
6A is reflected and incident on the rear slope M2.

In this state, the light receiving elements 18 and 20 are held at the front focus position and the rear focus position with respect to the focal position of the reflected light beam LA2, and the reflected light beam LA2 has a circular optical spot on each light receiving surface. SP1 and SP2 are formed. As a result, in the magneto-optical head 1, after adding signals are obtained by the adding circuits 22 and 24 with respect to the output signals of both light receiving surfaces, the subtracting circuits 26 and 28 subtract the subtracted signals from the added signal and the output signal of the central light receiving surface, respectively. By obtaining it, the defocus amount on each light receiving surface can be detected.

As a result, in the magneto-optical head 1, the output signals of the subtraction circuits 26 and 28 are subtracted by the subtraction circuit 30 to form the focus error signal SER, and the focus error signal SER is used as a reference. It is designed so that it can be used as a caching servo. Further, the output information of each light receiving surface is added / subtracted to reproduce recorded information.

[0009]

By the way, in the magneto-optical head 1 using the micro-prism contactor 16, the overall structure can be simplified, and the overall shape can be reduced accordingly.

However, in the prisms 16A and 16B, when the shape is reduced, the working accuracy is deteriorated, and the yield of the spectral magnetic head itself is deteriorated. That is, in the prisms 16A and 16B, when the height and the lateral width are reduced to about 1 mm, it is necessary to grind the prisms 16A and 16B at the joint surface M1 and then polish the whole to form a predetermined shape. is there.

However, when processed in this manner, it becomes difficult to maintain the respective surfaces of the prisms 16A and 16B in the correct positional relationship with respect to the joint surface M1.

In this case, as shown in FIG. 11, the joint surface M1
In contrast, when the relationship between the side surfaces of the light receiving elements 18 and 20 is disturbed and the angle of 45 degrees of the joint surface M1 is disturbed, the reflection direction (φ) of the reflected light beam on the joint surface M1 is disturbed in the vertical direction. become. As a result, as shown in FIG. 12, on the light receiving surface of the light receiving element 20, the position of the light spot SP2 is displaced in the direction in which the light receiving elements 18 and 20 are arranged, and the reflected light beam LA2 cannot be correctly incident on the light receiving element 20. ..

On the other hand, as shown in FIG. 13, when the relationship between the side surfaces of the prisms 16A and 16B with respect to the cemented surface M1 is disturbed, the reflection direction (θ) of the reflected light beam at the cemented surface M1 is changed to the left and right. Will be disturbed. As a result, as shown in FIG. 14, on the light receiving surface of the light receiving element 20,
The position of the light spot SP2 is displaced in the direction orthogonal to the arrangement direction of the light receiving elements 18 and 20, and in this case also, the reflected light beam L
A2 cannot enter the light receiving element 20 correctly.

The present invention has been made in consideration of the above points, and it is an object of the present invention to propose an optical head capable of improving the yield as compared with the conventional case, when using a micro prism prism.

[0015]

In order to solve such a problem, according to the present invention, an optical recording medium 8 is irradiated with a light beam LA1 and recorded on the optical recording medium 8 based on a reflected light beam LA2 of the light beam LA1. In the optical head for reproducing the recorded information, the focusing lens 14 for focusing the reflected light beam LA1 and the reflected light beam LA2 focused by the focusing lens 14 are provided.
And a first light receiving element 40 which is disposed at the front pin position of the first branched reflected light beam and divides the light receiving surface.
And is arranged at the back pin position of the second branched reflected light beam,
A second light receiving element 42 formed by dividing the light receiving surface is provided. The first and second light receiving elements 40, 42 are integrally formed on a predetermined substrate 44, and the light receiving surface is divided in different directions. Set.

[0016]

In the first and second light receiving elements 40 and 42,
If the dividing directions of the light receiving surface are set to different directions, even if the emitting directions of the first and second branched reflected light beams are disturbed,
The light receiving position can be easily adjusted.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail with reference to the drawings.

In FIG. 1, reference numerals 40 and 42 denote light receiving elements of a microprism contactor, which are integrally formed on a semiconductor substrate 44.

Here, in the light receiving element 42, the light receiving elements 40 and 4 are used similarly to the conventional microprism contactor.
While the light receiving surface is divided into three in the direction orthogonal to the arrangement direction of the two, in the light receiving element 40, the light receiving surface is divided into three in the direction orthogonal to the dividing direction of the light receiving element 42. Further, in the light receiving elements 40 and 42, the respective divided light receiving surfaces are formed to be longer than the conventional light receiving elements 18 and 20, whereby the prisms 16A and 16B are formed.
The reflected light beam can be surely received even when the shape of is disturbed.

That is, FIG. 2 corresponding to FIGS.
When the angle of 45 degrees is disturbed, the light spot SP2 can be formed on the light receiving element 42 by lengthening the light receiving surface on the side of the light receiving element 42 when the angle of 45 degrees is disturbed.

On the other hand, as shown in FIG. 3 corresponding to FIGS. 13 and 14, when the angle of the side surface with respect to the joint surface M1 is disturbed, in the magneto-optical head, the dividing direction of the light receiving element 40 is changed. By setting the direction orthogonal to the conventional one and lengthening the light receiving surface, the entire light receiving element 40 is arranged so as to be laterally displaced with respect to the prisms 16A and 16B.
An optical spot SP1 can be formed on it.

Further, an angular disorder of 45 degrees, the joint surface M
In the case where the disturbance of the angle of the side surface with respect to No. 1 occurs at the same time, as shown in FIG.
The light spots SP1 and S are arranged on the light receiving elements 40 and 42 by displacing them as a whole in the lateral direction with respect to 6A and 16B.
P2 can be formed.

As a result, even when the processing accuracy of the prisms 16A and 16B is low, the light receiving elements 40 and 42 can reliably receive the reflected light beam LA2.

According to the above construction, in the light receiving element of the micro-prism detector, the light receiving surface is set to be long and the dividing directions of the light receiving surface are set to be orthogonal to each other, whereby the processing accuracy of the prisms 16A and 16B is improved. Even if it is low, the light can be reliably received, and the yield of the magneto-optical head can be improved accordingly.

In the above embodiment, the light receiving element 4
Although the case where the division directions of 0 and 42 are set to be orthogonal to each other has been described, the present invention is not limited to this, and the point is that the division directions may be held differently. For example, as shown in FIG. The angle may be set to.

Further, in the above-mentioned embodiment, the case where the light receiving surface of each of the light receiving elements 40 and 42 is divided into three has been described, but the present invention is not limited to this and, for example, as shown in FIG.
The present invention can be widely applied to a case where the light receiving surface divided as necessary is further divided into two.

Further, in the above-mentioned embodiment, the case where the present invention is applied to the magneto-optical head has been described, but the present invention is not limited to this and can be widely applied to the optical head such as a compact disk player.

That is, in FIG. 7, reference numeral 50 denotes an optical head of a compact disc player as a whole, and a laser light source 54 and light receiving elements 56 and 58 are integrally formed on a semiconductor substrate 52.

In the optical head 50, the light receiving element 56,
A trapezoidal prism 60 is disposed on the 58, and the prism 60 and the light receiving elements 56 and 58 form a microprism detector. The prism 60 is arranged such that the laser light source 54 side is an inclined surface, and the light beam LA1 emitted from the laser light source 54 is reflected by the inclined surface to be emitted to the objective lens 62 and the compact disk 64, and at the same time, reflected by the compact disk 64. The light beam LA2 is transmitted and guided to the light receiving element 56.

At this time, the prism 60 focuses the reflected light beam LA2 on the light receiving element 56 in the state of the front focus. On the other hand, the reflected light beam reflected by the light receiving element 56 is reflected by the reflection film M3 formed on the upper surface and is focused on the light receiving element 58 in the state of the rear focus.

Thus, the light-receiving surfaces of the light-receiving elements 56 and 58 can be lengthened, and the dividing directions can be set to different directions to improve the yield of the optical head even when the shape of the prism 69 is disturbed.

Furthermore, in the above-described embodiment, the case where the light receiving surface is made long and the division direction is set to different directions has been described, but the present invention is not limited to this, and only the division direction differs if necessary. It may be set to.

[0033]

As described above, according to the present invention, the reflected light beam of the optical recording medium is branched and received in the state of front pinning and rear pinning, and a focus error signal is formed based on the light receiving result. In this case, by setting the light receiving surface division directions of the respective light receiving elements to different directions, the reflected light beam can be reliably received even if the shape of the light branching means is disturbed, and the yield can be improved accordingly. You can get a light head.

[Brief description of drawings]

FIG. 1 is a plan view showing a light receiving element of a magneto-optical head according to an embodiment of the present invention.

FIG. 2 is a schematic diagram for explaining a case where an angle of a joint surface is disturbed.

FIG. 3 is a schematic diagram for explaining a case where a side surface of a prism is disturbed with respect to a cemented surface.

FIG. 4 is a schematic diagram for explaining an angle of a joint surface and a case where a side surface of a prism is disturbed with respect to the joint surface.

FIG. 5 is a plan view showing a light receiving element whose light receiving surface is divided by 45 degrees.

FIG. 6 is a plan view showing a light receiving element obtained by further dividing the light receiving surface.

FIG. 7 is a schematic diagram showing an optical head of a compact disk player.

FIG. 8 is a schematic diagram showing a magneto-optical head using a micro-prism detector.

FIG. 9 is a perspective view showing a micro prism detector.

FIG. 10 is a perspective view showing the light receiving element.

FIG. 11 is a schematic diagram used to explain an irregular angle of a joint surface.

FIG. 12 is a schematic diagram for explaining the light reception result.

FIG. 13 is a schematic diagram used to explain a disorder of a side surface of a prism with respect to a bonding surface.

FIG. 14 is a schematic diagram for explaining the light reception result.

[Explanation of symbols]

1 ... Magneto-optical head, 16 ... Micro prism detector, 16A, 16B, 60 ... Prism, 18, 2
0, 40, 42, 56, 58 ... Light receiving element.

Claims (1)

[Claims] 1. An optical head which irradiates an optical recording medium with a light beam and reproduces recorded information recorded on the optical recording medium based on the reflected light beam of the light beam, and focuses the reflected light beam. A focusing lens, an optical branching means for branching the reflected light beam focused by the focusing lens to output first and second branched reflected light beams, and a front pin for the first branched reflected light beam Placed in a position,
A first light-receiving element that divides the light-receiving surface, and a second light-receiving element that is disposed at a rear pin position of the second branched reflected light beam,
A second light receiving element formed by dividing the light receiving surface, wherein the first and second light receiving elements are integrally formed on a predetermined substrate, and the dividing directions of the light receiving surface are set to different directions. Characteristic light head.