JPH0727642B2 - Optical head adjuster - Google Patents

Description

The present invention relates to an optical head adjusting device, and more particularly to an optical head adjusting device used when assembling and adjusting an optical head used in an optical disk device.

[Prior Art] The configuration of the optical system of the optical head is, for example, entirely shown in FIG. A-1 of Nikkei Electronics 1983.11.21 p197, the focus detection system in FIG. 9 of p202, and the tracking detection in FIG. 10 of p203. The system is shown. In the focus detection system of this optical system, the positions of parts such as the two-division optical sensor and the spherical lens are adjusted so that the focus error signal becomes 0 when the optical disk reflection surface is located at the focus position of the objective lens (narrowing lens). It is also necessary to adjust the position of the two-division photodetector so that the tracking error signal can be correctly obtained when the optical disk reflecting surface is located at the focal position of the objective lens. is there.

However, it is difficult to accurately position the optical disk reflecting surface at the focal point of the objective lens, and it is difficult to position it accurately. Therefore, when adjusting the position of the 2-split photodetector, move the objective lens up and down. Then, the relative position between the objective lens focal position and the optical disk reflecting surface is changed, and the two-division photodetector is adjusted using the error signal waveform.

[Problems to be Solved by the Invention] In the above-mentioned prior art, it is difficult to accurately position the optical disk reflection surface at the focal position of the objective lens, and therefore, a two-division photodetector using an error signal waveform or the like is used. There is a problem that an adjustment method for the photodetector is required, the adjustment takes time, and automation is difficult.

An object of the present invention is to solve the above-mentioned problems of the prior art, provide an apparatus for focusing on a position corresponding to an optical disk reflection surface, and provide an optical head adjusting apparatus which can easily and quickly adjust an optical head. To provide.

[Means for Solving Problems] An optical head adjusting device of the present invention is a half mirror that reflects a part of light emitted from an objective lens of an optical head and transmits the other part, and a half mirror. A half mirror / condenser lens assembly including a formed condenser lens, and a part of light emitted from the condenser lens of the half mirror / condenser lens assembly, and a direction and a direction of light emitted from the condenser lens. An optical direction detection system that outputs an angle formed by the optical axis of the optical lens as a first electric signal, and a part of the light emitted from the condenser lens of the half mirror / condenser lens assembly to receive the objective of the optical head. A focus signal detection system that outputs a second electric signal indicating the amount of positional deviation between the focal point of the light emitted from the lens and the reflecting surface of the half mirror, and an optical head, a half mirror, and a collector based on the first electric signal. Hikari Ren Means for adjusting the relative position for optical axis alignment of the lens assembly,
Second means for moving the half mirror / condensing lens assembly so that the light emitted from the objective lens of the optical head is focused on the half mirror based on the second electric signal. I am trying.

[Operation] The first means adjusts the relative positional relationship between the optical head and the half mirror / condensing lens assembly on the basis of the first electric signal output from the photodetection system, and adjusts the optical axis of the objective lens. Match the optical axes of the condenser lenses. In this state, when the light passing through the half mirror / condenser lens assembly is guided to the focus signal detection system, an error signal which is a second electric signal is generated according to the relative position between the focus position of the condenser lens and the focus position of the objective lens. Can be obtained. The half mirror and the condenser lens are integrally formed, and the focus signal detection system is adjusted in advance so that the error signal becomes 0 when the focus position of the objective lens coincides with the reflection surface of the half mirror. Therefore, according to the second signal, the second means moves the half mirror / condensing lens assembly as a unit so that it becomes 0, so that the objective lens focal position is located on the half mirror reflecting surface. Can be controlled in the same way.

The above-mentioned first means and second means can be easily realized by known means.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings.

The accompanying drawings are views showing the configuration of an optical head adjusting apparatus showing an embodiment of the present invention.

The optical head adjusting apparatus of the embodiment shown in this drawing includes an optical head 1 as an adjustment target, a half mirror / condensing lens assembly 32, a light direction detecting system 22, and a focus signal detecting system 12.

The optical head 1 includes a semiconductor laser 2, a beam splitter 4 for the light 3 emitted from the semiconductor laser 2, an objective lens 5, and a focus-tracking signal detection system 8.

The focus-tracking signal detection system 8 of the optical head 1 is
Convex lens 18 arranged to face the beam splitter 4
, Beam splitter 19, and photodetector 20a for positioning,
20b (see JP-A-61-224144).

The half mirror / condensing lens assembly 32 includes a half mirror 6 having a reflecting surface 7 for reflecting the light emitted from the objective lens 5 of the optical head 1, and a collecting mirror arranged in front of the reflecting surface 7 in the light traveling direction. And an optical lens 9. The half mirror 6 and the condenser lens 9 are attached to the stem 13. The stem 13 is supported by a spring 14 and is movable in the direction of arrow a in the accompanying drawings by an actuator (not shown). Therefore,
The positions of the half mirror 6 and the condenser lens 9 are integrally controllable in the direction of the arrow a.

An optical direction detection system 22 including a beam splitter 10 and an optical position detector 11 is arranged in front of the traveling direction of the light emitted from the condenser lens 9. The optical position detector 11 is arranged in front of the traveling direction of one of the light beams split by the beam splitter 10.

The focus signal detection system 12 is arranged in front of the traveling direction of the other light split by the beam splitter 10. The focus signal detection system 12 includes a convex lens 15, a beam splitter 16, and photodetectors 17a and 17b, and the focus position of the objective lens 5 is the reflection surface 7 of the half mirror 6.
The positions of the photodetectors 17a and 17b are set so that the error signal, which is the output difference between the photodetectors 17a and 17b, becomes 0 when the photodetectors 17a and 17b are above (see Japanese Patent Laid-Open No. 61-224144).

The optical head adjusting device of the above embodiment operates as follows.

The light 3 emitted from the semiconductor laser 2 of the optical head 1 passes through the beam splitter 4 and the objective lens 5 and reaches the half mirror 6.

On the reflection surface 7 of the half mirror 6, a part of the light is reflected to reach the unadjusted focus-tracking signal detection system 8, and the other part is transmitted to become approximately parallel light by the condenser lens 9. The beam splitter 10 splits the beam in two directions.

One of the lights separated by the beam splitter 10 is
Focus on the optical position detector 11. When the optical axes of the objective lens 5 and the condenser lens 9 are deviated, the light passing through the condenser lens 9 is inclined with respect to the optical axis of the condenser lens 9, and the light on the optical position detector 11 is tilted according to the inclination. The position of the focal point also changes. Since the output of the optical position detector 11 changes according to the position of the focal point,
It is possible to detect the inclination between the direction of the light passing through the condenser lens 9 and the optical axis of the condenser lens 9. The other of the lights split by the beam splitter 10 reaches a focus signal detection system 12.

In the focus signal detection system 12, the convex lens 15, the beam splitter 16, and the two photodetectors 17a and 17b are used to shift the position of the focus of light from the objective lens 5 of the optical head 1 and the reflection surface 7 of the half mirror 6. An error signal is output according to the amount. Further, the focus signal detection system 12 is set in advance to output an error signal 0 when the focus of the light from the objective lens 5 is on the reflecting surface 7 of the half mirror 6. Optical head 1
When the optical axes of the objective lens 5 and the condenser lens 9 deviate depending on the position of, the light after passing through the condenser lens 9 is tilted with respect to the optical axis of the condenser lens 9, so that the focus signal detection system 12 operates correctly. Even if the focus position of the objective lens 5 is on the reflecting surface 7 of the half mirror 6, the error signal does not become zero.

In order to prevent this, whether the angle between the direction of the light emitted from the condenser lens 9 and the optical axis of the condenser lens 9 by the light position detector 11 in the light direction detection system 22 is within a predetermined range or not. Check. Then, if it deviates from the predetermined range, the position of the optical head 1 is adjusted so that it is within the predetermined range. This adjustment may be performed manually, or may be automatically performed using a known means. When the angle formed by the direction of the light emitted from the condenser lens 9 and the optical axis of the condenser lens 9 falls within a predetermined range, it is not necessary to perform the adjustment work using the optical position detector 11.

After the light position detector 11 sets the angle between the direction of the light emitted from the condenser lens 9 and the optical axis of the condenser lens 9 within a predetermined range, the light detectors 17a and 17b of the focus signal detection system 12 The positions of the objective lens 9 and the half mirror 6 integrated by the stem 13 are controlled in the direction of arrow a so that the error signal which is the output difference becomes zero. As a result, the focal position of the objective lens 5 is located on the reflecting surface 7 of the half mirror 6. This adjustment may be performed manually or automatically by a known mechanism.

In this state, the positions of the photodetectors 20a and 20b of the unadjusted focus-tracking detection system 8 are adjusted. In this case, the photodetector 2
It may be adjusted so that the output difference between 0a and 20b becomes zero. Therefore, it is not necessary to observe and adjust the waveform as in the prior art. Therefore, the adjustment of the optical head 1 can be performed easily and in a short time, and automation can be performed.

In the present invention, the light direction detection system 22 and the focus signal detection system 12 are
Is not limited to the structure shown in the drawings,
Even if it has another structure, the point is that it has a predetermined function.

[Advantages of the Invention] According to the present invention, since adjustment is possible with the reflecting surface of the half mirror positioned at the focal position of the objective lens, it is not necessary to observe the signal waveform for adjustment, and the adjustment is simple. This has the effect of shortening the adjustment time.

[Brief description of drawings]

The accompanying drawings are block diagrams illustrating an embodiment of the present invention. 1 ... Optical head, 2 ... Semiconductor laser, 5 ... Optical head objective lens, 6 ... Half mirror, 7 ... Half mirror reflecting surface, 8 ... Focus-tracking signal detection system, 9
...... Condensing lens, 11 …… Optical position detector, 12 …… Focus signal detection system, 13 …… Stem with integrated half mirror and condenser lens, 22 …… Light direction detection system, 32 …… Half mirror / condenser lens assembly.

Claims (1)

[Claims] 1. A half mirror / condenser comprising a half mirror for reflecting a part of light emitted from an objective lens of an optical head and transmitting another part of the light, and a condenser lens integrally formed with the half mirror. A part of the light emitted from the lens assembly and the condenser lens of the half mirror / condenser lens assembly is received, and the angle formed by the direction of the light emitted from the condenser lens and the optical axis of the condenser lens is determined by the first electric field. A light direction detection system that outputs as a signal, a part of the light emitted from the condenser lens of the half mirror / condenser lens assembly, and the focus of the light emitted from the objective lens of the optical head and the reflection surface of the half mirror. A focus signal detection system for outputting a second electric signal indicating the amount of positional deviation of the optical head, means for adjusting the relative position of the optical head and the half mirror / condensing lens assembly based on the first electric signal, And an optical head adjusting device for moving the half mirror / condensing lens assembly so that the light emitted from the objective lens of the optical head is focused on the half mirror based on the electric signal of .