JPH05225576A - Method for adjusting optical axis of optical head - Google Patents

Abstract

PURPOSE:To reduce man-hour and to improve quality by adjusting the optical axis of a separation type optical head easily, effectively and without the damage of an optical parts. CONSTITUTION:The fixed optical system of the separation type optical head is mounted on a mounting base 2 and mounted on a single body base 1 after adjusting with a single body and the adjustment of the optical axis with a moving part 4 is facilitated by adjusting the position and the attitude of the mounting base 2. Further, a structure facilitating the adjustment is provided by providing a notched part and a long hole for housing an eccentric pin on the mounting base 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for aligning an optical axis of an optical system of an optical head of an optical disk device and its component structure.

[0002]

2. Description of the Related Art As a technique relating to optical axis alignment of an optical head for reproducing information recorded on a conventional video disc or compact disc in an optically non-contact state, there is one disclosed in Japanese Utility Model Publication No. 3-22729. is there.

In this method, a laser beam is applied to the information recording surface of the disk, and a reflected beam from the disk is applied to the detection section of the light receiving element to convert it into an electric signal. In order to capture it as a signal, it is necessary to accurately irradiate the detection beam of the light receiving element with the reflected beam having the adjusted focus. Therefore, conventionally, the position of irradiation of the reflected beam and the position of the detector of the light receiving element are aligned solely depending on the accuracy of the parts and the assembly accuracy at the time of assembly. The utility model described above relates to an optical axis adjusting device for this purpose. By the way, this optical head is of a type in which the entire optical system moves as a unit to irradiate the information storage surface with a laser beam. However, in order to increase the speed of information retrieval, a separate type optical head that moves only a part of the optical system has been adopted. This is to move relatively light parts only of the tracking mirror and the autofocus mechanism, and fix relatively heavy parts such as a semiconductor laser, a collimator lens, a polarization beam splitter, and a light receiving element. Because of this structure,
The following problems occurred.

If the optical axis of the optical system of the fixed part and the moving direction of the movable part do not match, the laser beam irradiation position on the optical system of the movable part changes depending on the position of the movable part. The irradiation state of the reflected beam on the beam changes, and accurate information cannot be captured. Therefore, in the separated type optical head, it is necessary to adjust the optical axis more accurately than in the conventional integrated type optical head.

Conventionally, the optical axis of the split type optical head has been adjusted by finely adjusting the mounting direction of optical system parts such as a semiconductor laser and a polarization beam splitter.

[0006]

In the conventional method for finely adjusting the mounting direction of each component of the optical system such as the semiconductor laser of the optical system and the polarization beam splitter, the optical system is adjusted according to the tightening condition of the tightening screw. The axis was greatly displaced, and it was difficult to finely adjust the optical axis. Further, since the optical system component is contacted during the fine adjustment, the optical system component may be damaged. The objects of the present invention are as follows.

(1) Do not touch individual optical system parts,
Provide an adjustment method that allows easy delicate optical axis alignment.

(2) To provide an assembly base for an optical system component having a structure that facilitates the above adjustment method.

[0009]

In order to achieve the above object, the present invention employs the following technical means.

(1) Do not touch individual optical system parts,
As an adjustment method that allows easy delicate optical axis alignment, a fixed optical system was attached to one assembly base, and the direction of the assembly base was finely adjusted.

(2) The assembly base is provided with a slot for accommodating the cutout portion and the eccentric pin so that the fine adjustment of the rotation angle in the biaxial directions is easy.

[0012]

The technical means of the present invention functions as follows.

(1) Since the fixed optical system is attached to one mounting base and the direction of the mounting base is finely adjusted, damage can be prevented because it does not come into contact with each easily damaged optical system. Moreover, delicate adjustment can be easily performed by adjusting the direction of the assembly base, which is a relatively large component, not a small component.

(2) Since the mounting base is provided with the notch, the mounting base is slightly deformed, and the direction can be finely adjusted. Further, by providing the eccentric pin-accommodating elongated hole, it is possible to make the subtlety. Easy angle adjustment.

[0015]

EXAMPLES Next, examples of the present invention will be described.

FIG. 1 shows an optical axis aligning method according to claim 1.
It is an example of a one-beam type separated optical head to which the optical component assembling base according to claim 2 is applied. Body base 1
The optical component assembling base 2 of claim 2 is attached to the above, and the fixing portion optical system component described later is attached thereto. Further, a movable portion 4 slidable on the guide rail 3 is attached. The above-mentioned fixed part optical system includes a semiconductor laser 5, a collimator lens 6, a shaping prism 7, a polarization beam splitter 8, a quarter-wave plate 9, a two-division diffraction grating 1
It is composed of 0, a convex lens 11, a cylindrical lens 12, and a light receiving element 13.

FIG. 2 is an explanatory view of the optical system when the movable portion 3 is viewed from the side. Laser beam 15
However, the light is emitted through a tracking mirror 16 which also serves as a rising mirror and an objective lens 17 having an automatic focusing function.

FIGS. 3 and 4 show how the base is attached. FIG. 3 is a plan view showing a base mounted state, and FIG. 4 is a side view showing a base mounted state. The base 2 for assembling the optical parts,
A notch 2a and an elongated hole 2b for accommodating an eccentric pin are provided. The optical component assembling base 2 is assembled with a pin 21, which is a center of rotation, a bolt 22, a set screw 24 and a bolt 25, and an eccentric pin 23 is further assembled.

An example of the optical axis alignment method in this case will be described. First, a predetermined optical component is mounted on the optical component mounting base 2 on the basis of mechanical dimensions, and the laser beam detection sensor and the reflection mirror are placed at a position corresponding to the center position of the sliding range of the movable portion 4. Adjusting the collimator lens 6 by detecting the state of the laser beam, further reflecting the laser beam by the reflecting mirror, adjusting the light receiving element 13 while detecting the reflected light, the fixed optical Complete the adjustment of the system alone.

Next, the optical component assembling base 2 with the fixed optical system being assembled is temporarily assembled with the main body base 1 with the guide rail 3 and the movable portion 4 assembled. Here, the laser beam sensor is placed at the position of the optical disc 14 in FIG. 2, the movable part 4 is moved, and the laser beam spot is set in a predetermined state within the sliding range as shown in FIG. Finely adjust Xθ and Yθ in FIG. Next, a method of fine adjustment will be described. First, the adjustment in the Yθ direction is performed by rotating the eccentric pin 23 by a minute angle with the bolts 22 and 25 temporarily tightened. Next, the adjustment in the Xθ direction is performed by slightly rotating the push screw 24. At this time, since there is the cutout 2a,
The base 2 for assembling the optical parts is capable of being sensitive to minute adjustments. Further, in this method, rather than adjusting each small optical component, a relatively large base is adjusted, so that delicate adjustment of Xθ and Yθ can be easily performed. After completing the adjustment, fully tighten the bolts 22 and 24 to complete the work.

FIG. 5 shows an optical axis aligning method according to claim 1.
It is an example of a two-beam type separable optical head to which the base for assembling the optical component shown in claim 2 is applied. Body base 31
The guide rail 33 and the movable portion 34 are mounted on the top.
In the case of two beams, there are optical component assembling bases 32 and 45, and optical components are attached to each of them. And each base is similar to the mounting base 2 in the case of 1 beam,
It is attached to the main body base 31. In the example of FIG. 5, the reading optical system is attached to the base 32, and the laser 35, the collimating lens 36, and the polarization beam splitter 3 are included.
7, an optical axis correction prism 38, an optical axis correction prism 39, a convex lens 40, a micro prism 41, and a light receiving element 42 are attached. A writing optical system is attached to the base 45, and a laser 46, a collimator lens 47, and a shaping prism 4 are attached.
8, polarization beam splitter 49, quarter wave plate 50, two-division diffraction grating 51, convex lens 52, cylindrical lens 53, light receiving element 54, and a wavelength filter 55 that reflects only the writing laser and passes the reading laser. Is installed. Here, the reading laser and the writing laser have different wavelengths. Next, an adjusting method in the case of this two-beam method will be described. Attached to each base 32, 45,
The reading optical system and the writing optical system are individually adjusted in the same manner as in the case of the one-beam method, and after temporary assembly, the laser beam sensor is placed at the position of the optical disk 14 as described above, The movable part 34 is moved while irradiating the above laser, and the adjustment is performed as described above. Also,
In the case of the two-beam method, the relative positional relationship between the two beams is adjusted at the same time. This is because it is necessary to maintain a constant interval between the two beams in order to operate the read-after-write function (the function that checks the writing state immediately after writing).

As described above, since each fixed optical system is temporarily adjusted by itself and then the mounting position and posture of the assembly base is adjusted, delicate adjustment can be easily performed.
It also becomes possible to prevent damage to the optical components. Also, adjustment is only required to rotate the screw from above, and the adjustment process is a combination of simple processes, which facilitates automation and reduces costs.

[0023]

According to the present invention, the optical axis of the separate type optical head can be aligned easily and efficiently without damaging the optical parts, which has a great effect on reduction of man-hours and improvement of quality.

[Brief description of drawings]

FIG. 1 is a plan view of a one-beam type separated optical head.

FIG. 2 is an explanatory view seen from a side surface of a movable part optical system.

FIG. 3 is a plan view of a 1-beam type base mounted state.

FIG. 4 is a side view of a 1-beam type base attachment.

FIG. 5 is a plan view of a two-beam type separation-type optical head.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Main body base, 2 ... Assembly base, 2a ... Notch part, 2b ... Eccentric pin accommodation slot, 23 ... Eccentric pin.

Claims (2)

[Claims] 1. In an optical disk device, the optical system is composed of a fixed part and a movable part, and the optical axis direction is adjusted by adjusting the position / posture of a base on which the optical parts of the fixed part of the separation type optical head are assembled. A method for aligning the optical axis of an optical head, characterized by: 2. An optical component assembling base, characterized in that, in order to apply the optical axis aligning method of claim 1, an elongated hole for accommodating a notch portion and an eccentric pin is provided.