JPH056568A - Optical head device - Google Patents

Abstract

(57) [Summary] [Object] The object of the present invention is to easily adjust the optical axis,
It is to provide an optical head that does not cost much. According to the optical head device of the present invention, a light source and an optical disk are formed by two refracting bodies which are movable and whose setting of a refraction angle can be changed and which are arranged in an optical path from the light source to the optical member. It is easy to match the optical axis defined between them and the optical beam traveling from the light source to the optical disc. On the other hand, in the first and second refracting bodies, the convex surface and the concave surface which are complementary to each other are joined, so that the optical beam passing through the two refracting bodies and the light beam entering the two refracting bodies are incident. The beam spot is substantially the same as that of the above-mentioned light beam. Therefore, while suppressing the processing cost of optical parts,
There is provided an optical head having high alignment between the optical beam and the optical axis.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for recording or reproducing information, and more particularly to an optical head device for reproducing information from an information recording medium using focused light.

[0002]

2. Description of the Related Art In an information processing device, for example, an optical disc device, an information recording medium, that is, an optical disc on which a support such as glass or plastic is coated with a metal to record or reproduce information, and information is recorded on the optical disc. It includes a light source or semiconductor laser device to be recorded or reproduced for reproduction, and a signal reproduction circuit for reproducing information recorded on the recording medium, including a photodetector. Further, between the laser and the recording medium, and between the recording medium and the reproducing circuit, the laser beam traveling from the laser to the recording medium is focused and recorded. An optical head for guiding the laser beam reflected from the medium to the reproducing circuit is arranged. Further, the optical head has a mirror for returning an optical beam generated from a light source toward the recording medium, and the optical beam for returning through the mirror on the recording medium. It includes a focusing objective lens.

In many optical heads today, the objective lens and the folding mirror or actuator unit are constructed separately from the laser and the reproducing circuit in order to increase the access speed.

[0004]

In the above optical head,
Since the light beam is transmitted along the optical axis defined between the light source, the actuator unit and the photodetector, the optical axis is aligned with very high accuracy. There is a need. In particular, an inclination (angle difference) occurs between the optical axis between the actuator (mirror) and the photodetector and the optical beam transmitted between the actuator and the photodetector. When the incident angle of the light beam with respect to the photodetector is 0
It is known that the reliability of the reproduced signal is significantly reduced when the value is other than °. For example, as a method of detecting an optical beam used for signal reproduction, push-
When the pull method is used, there is a problem that the tracking operation used for controlling the track becomes inaccurate. On the other hand, if the processing accuracy for the actuator, that is, the mirror and the optical lens is excessively increased, there is a problem that the cost of the head device increases.

An object of the present invention is to provide an optical head in which the optical axis can be easily adjusted and the cost is low.

[0006]

The present invention has been made on the basis of the above problems, and a light source, a reflecting means for changing a traveling direction of light from the light source, and a traveling direction via the reflecting means are provided. An optical member for condensing the changed light, and a movable and changeable setting of the refraction angle are formed in accordance with the reflection angle of the light reflected through the reflection means, and the light source is used to change the setting. An optical head device having a refracting body arranged in an optical path toward an optical member.

[0007]

In the optical head device according to the present invention, the two light sources, which are movable and whose setting of the refraction angle can be changed, are arranged in the optical path from the light source to the optical member. It is easy to match the optical axis defined between them and the optical beam traveling from the light source to the optical disc. That is, the two refracting bodies have the convex surface and the concave surface, which are complementary to each other, joined together. Further, by changing the angle at which the convex surface and the concave surface are joined, it is possible to change the optical paths of the incident light beam and the outgoing light beam.
The beam spots that have passed through the two refracting bodies and the beam before entering the two refracting bodies have substantially the same beam spots. When aligning the optical path of the optical axis with the optical axis, it is not necessary to consider changes in optical characteristics such as aberration due to a refraction element inserted in the optical path.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, an optical head device 20 uses an optical beam L from a light source which will be described later as an information recording medium, that is, an optical disc.
Movable optical means 30 for transmitting toward 10, a slider 34 movably supporting the movable optical means 30, and a light source (not shown) are integrally formed, and are formed separately from the movable optical means 30. It includes a photodetector 40 for detecting the reflected light beam L from the optical disk 10 and a base 36 for holding the photodetector 40 and the slider 34.

The movable optical means 30 is a mirror 32 for reflecting the light beam L generated from the light source toward the optical disc 10, and the light beam reflected by the mirror 32.
A focusing lens 22 for focusing the beam L on the optical disc 10, and an optical beam L and the optical beam L which can be tilted at a desired angle with respect to the optical beam L and are directed from the light source to the optical disc 10. First and second refracting bodies 26 for aligning the optical axis defined between the detector 40 and the optical disk 10
And 28.

The refracting bodies 26 and 28 have a convex surface 26b and a concave surface 28a, which have the same curvatures and have respective complementary powers. The above refractor
26 and 28 may be a cylindrical convex lens and a cylindrical concave lens, respectively.

The (parallel) light beam L incident on the entrance surface 26a of the first refracting body 26 is emitted from the exit surface 16b of the refracting body 26.
When the light beam passes through, the light beam is once focused and guided to the incident surface 28a of the second refracting body 28 as a focused light beam L. After this,
It is converted into a divergent light beam L via the refracting body 28, is returned to the (parallel) light beam L via the emission surface 28b, and is transmitted to the mirror 32. Incidentally, in FIG.
The characteristic of the optical beam L reflected from the optical disk 10 is shown from the direction to the refracting body 28.

On the other hand, a (parallel) light beam L directed to the optical disk 10 from a light source (not shown) (integrated in the photodetector 40) is reflected by the mirror 32 and the second refraction. It is incident on the incident surface 28b of the body 28. This light beam L
Is converted into a divergent light beam L via the second refracting body 28 and passes through the emission surface 28a. The light beam L from the exit surface 28a is incident on the entrance surface 26b of the first refracting body 26, and is focused through the refracting body 26. The light beam L having this focusing property is emitted from the exit surface 26a of the refracting body 26.
Is passed through the optical path, is converted into a substantially parallel light beam L, and is transmitted to the objective lens 22. (The optical beam described here from the light source to the optical disk 10 is omitted in FIG. 1.) The movable optical means 30.
(That is, the objective lens 22, the first refracting body 26, the second refracting body 28
And the mirror 32) are fixed on the slider 34. On the other hand, the slider 34 can freely move on the base 36 and is moved along the recording area of the optical disk 10. The base 36 may be, for example, a shaft and a bush, or a shaft and a bearing.

By the way, from the light source to the optical disk 10
The optical axis L defined between the light source (photodetector 40) and the optical disc 10 with respect to the optical beam L directed toward the optical beam L or returned from the optical disc 10 to the photodetector 40. Must be matched with high precision. in this case,
For example, the inclination (gap) between the slider 34 and the base 36, the surface accuracy of the surface of the slider 34 on which the movable optical member 30 is arranged (face tilt), the slider 34 and the movable portion. The inclination (gap) between the optical members 30, the surface accuracy of the movable optical member 30 with respect to the mirror 32 (surface tilt), the assembly accuracy of the mirror 32 and the first and second refracting bodies 26 and 28, that is, the above There is a problem in that many members must be machined with high precision, such as the surface precision (face-down) of the mirror 32.

In the optical head device shown in FIG. 1,
The parallelism between the reference surface of the slider 34 (the surface on which the movable optical member 30 is arranged) and the reference surface of the base 36 can be relatively easily obtained by machining. In this state, the photodetector 40 is fixed to the base 36. Here, the optical path deviation angle of the optical beam L directed from the light source (photodetector 40) to the optical disc 10 and the optical beam L returned from the optical disc 10 to the photodetector 40 (light source) is 90 °. A reference mirror for assembly and adjustment (not shown) is used to maintain the optical path of the optical beam L to the light source (photodetector 40).
And the movable optical member 30 are aligned with the optical axis defined between them. This means that, for example, while monitoring the angle between the light beam L reflected from the optical disk 10 and the base 36, a collimating lens (not shown) (the photodetector 40) is used.
That is, it is easy by adjusting the position of (included in the light source). Therefore, the mirror surface 32 of the movable optical member 30 is
And an optical axis defined between the light source (photodetector 40) and the light source toward the optical disc 10 (the optical disc
Returning from 10 to the photodetector 40) The light beam L is matched with high precision.

On the other hand, as shown in FIG. 2 or 3, the reference surface of the slider 34 (the surface on which the movable optical member 30 is arranged) is relative to the reference surface of the base 36. When the mirror 32 is tilted or the processing accuracy of the mirror 32 is low, the first and second refracting bodies 26 and 28 are slid along the optical path of the optical beam L (that is, By offsetting / shifting the second surface or the convex surface 26b of the refracting body 26 and the first surface or the concave surface 28a of the refracting body 28, the optical beam L and the optical axis can be easily matched. Can be made

This means that the first and second refracting bodies 26 are
And the light beam L passed through the light beams 28 and 28 is reflected by the refracting bodies 26 and 28.
In the case where the convex surface 26b and the concave surface 28a, which have the same curvature as each other and have a complementary relation to the respective powers, are combined, the beam spot and the emission in the light beam L before the incidence are combined. The characteristic that the size of the beam spot in the subsequent optical beam L does not change is used.

Therefore, the light beam L traveling from the light source to the optical disc 10 and the photodetector reflected by the optical disc 10 are detected.
With respect to the optical beam L returned to 40, the light source (photodetector) is used without changing the beam spot of the optical beam L.
The optical axis defined between the optical disc and the optical disc 10 can be easily matched. In the state where the optical beam L and the optical axis are substantially aligned with each other, the contact surfaces of the first refracting body 26 and the second refracting body 28, that is, the convex surface 26b and the concave surface 28a are optically bonded. Glued by the agent.

[0018]

As described above, according to the present invention, the optical beam traveling from the light source to the optical disc via the objective lens and the optical beam returning from the optical disc to the photodetector via the objective lens. The beam and the optical axis defined between the light source (photodetector) and the optical disk are offset by the angle between two refracting bodies having refracting powers that are complementary to each other. The deviation between the optical path of and the optical axis of the optical head can be corrected. Further, since the two refracting bodies have the same curvature, and the convex surface and the concave surface having complementary relations to the respective powers are combined, the beam spot in the optical beam before the incidence is formed. The beam spot of the emitted light beam and the beam spot of the emitted light beam are maintained substantially the same.

Therefore, an optical head having a high matching between the optical beam and the optical axis can be provided while suppressing the processing cost of the optical component. Further, since high assembly accuracy can be easily obtained, the cost of the entire optical head is reduced.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an optical head that is an embodiment of the present invention.

2 is a schematic view showing a state where an optical beam and an optical axis are aligned by the optical head shown in FIG.

FIG. 3 is a schematic view showing another state in which the optical beam and the optical axis are aligned by the optical head shown in FIG.

[Explanation of symbols]

10 ... Optical disc, 20 ... Optical head, 22 ... Objective lens, 24
... Lens support member, 26 ... First refracting body, 28 ... Second refracting body, 30 ... Movable optical means, 32 ... Mirror, 34 ... Slider, 36
... base, 40 ... photodetector.

Claims (1)

Claim: What is claimed is: 1. A light source, a reflection means for changing a traveling direction of light from the light source, and an optical for condensing the light whose traveling direction is changed through the reflecting means. A member and a refracting body that is movable in accordance with the reflection angle of the light reflected via the reflecting means and has a changeable refraction angle setting, and is arranged in an optical path from the light source to the optical member. And an optical head device having: