JPS62188029A - Adjusting method for optical axis of objective of optical pickup - Google Patents

Abstract

PURPOSE:To adjust the tilt angle of the optical axis of an objective extremely easily by selecting a spacer with proper thickness among several kinds of spacers which are prepared and adjusting the angle of the lens optical axis. CONSTITUTION:A spacer 3 is arranged on a main body 2 across at least two spacers 7 and 8 which have thickness H1 and are arranged across a reference line 4. When the objective 1 is slanted to the reference line 4 by an angle thetaas shown by an arrow by adjusting the optical axis, various spacers which differ in thickness are prepared. Then, a spacer with proper thickness is selected among said prepared spacers and the spacers 7 and 8 are replaced with other spacers 7' and 8' to adjust the optical axis of the lens. Consequently, the base 3 and objective 1 are displaced to the positions of 3' and 1' respectively.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an optical pickup for recording and reproducing information on and from optical recording media such as optical discs such as compact discs and video discs, and optical recording media such as magneto-optical discs. The present invention relates to an objective lens optical axis adjustment method.

[Conventional technology]

2. Description of the Related Art Optical information recording and reproducing devices that record and reproduce information by projecting a light beam onto an optical recording medium such as an optical disk have been widely put into practical use.

As shown in FIG. 2, the optical pickup used in this device has an objective lens 1 fixed integrally with a base 3 placed on a main body 2 of the optical pickup. When assembling the optical pickup here.

Due to variations in the processing accuracy and assembly accuracy of each component, it may be necessary to adjust the optical axis so that the objective lens 1 is tilted at a predetermined angle with respect to the reference line 4 (which is a straight line perpendicular to the upper surface 5 of the main body 2).

Conventionally, the optical axis of the objective lens 1 is adjusted using the base 3 and the main body 2.
This was done by interposing a spacer 6 at one place between the two.

[Problem that the invention seeks to solve]

However, the above adjustment method has the following drawbacks.

That is, if one side of the base 3 is lifted from the main body 2 with the spacer 6 interposed, and the optical axis of the lens is tilted by a predetermined angle, for example, angle θ, the objective lens 1 and the base 3 are both shown by the two-dot chain line. Displaced to positions 11' and 3'. As a result, the position of the objective lens is raised by the distance Δ with respect to the optical axis direction. Therefore, there is a drawback that adjusting the inclination of the optical axis of the objective lens causes a positional change in the optical axis direction of the objective lens.

SUMMARY OF THE INVENTION An object of the present invention is to provide an objective lens optical axis adjustment method that eliminates the above-mentioned drawbacks.

[Means for solving problems]

The objective lens optical axis adjustment method according to the present invention is a method of adjusting the optical axis by tilting a base integrated with the objective lens of an optical pickup in order to read information recorded on a recording medium. A desired lens optical axis is set by interposing washers at at least two locations between the base and the main body, with the intersection of the objective lens optical axes as the center of rotation.

〔Example〕

FIG. 1 shows a principle diagram of the method for adjusting the optical axis of an objective lens according to the present invention. The main body 2 of the objective lens 11, the base 3, and the reference line 4 are the same as the structure of the conventional example shown in FIG. It is assumed that the base 3 is placed on the main body 2 via at least two spacers 7.8, both of which have a thickness of H, which are arranged so as to sandwich the reference line 4 between them.

Let us now consider a case where it becomes necessary to tilt the objective lens 1 by an angle θ in the direction of the arrow with respect to the reference line 4 due to optical axis adjustment. In the present invention, spacers having various thicknesses are prepared in advance. Therefore, when tilting the base 3 and tilting the objective lens that is fixed integrally with the base 3, select a spacer with an appropriate thickness from among several types of spacers with different thicknesses prepared in advance. The optical axis of the lens is adjusted by replacing spacers 7 and 8 in Figure 1 with other spacers 7' and 8', respectively.The state after adjustment is shown by the two-dot chain line in Figure 1A and Figure 1B. .

At this time, when replacing the spacer and tilting the base 3, the position of the intersection 0 between the reference line 4 and the lower surface 9 of the base 3 is not changed. - The inclination of the optical axis of the power objective lens 1 can be determined using an angle measuring device (not shown). Based on this result 3. and objective lens 1 are 3' and 1', respectively.
Displaced to the position.

Here, the distance between the lower surface 9 of the base 3 and the objective lens 1 is L=1
0m, and calculate the displacement Δ' of the objective lens 1 in the optical axis direction when adjusting the angle θ-11' with respect to the reference line, Δ' 8L (1-cos θ) -10 (1-coslo
)・0.0015m, and the amount of displacement is an extremely small value.

This value of Δ' will be compared with the amount of displacement Δ of the objective lens in the optical axis direction when the optical axis is adjusted at the same angle as described above using the conventional method shown in FIG. In FIG. 2, if the distance D between the reference line 4 and the base end opposite to the position where the spacer 6 is interposed with respect to the reference line 4 is 15 mm, and the thickness of the base is t-3 m, then 6w (L cos θ + t cos θ
+Dsinθ)−(L+t)=(10cosl
" + acosl " + 15sin1°) - (1
0+3)-0.26 cranes, resulting in a displacement approximately 170 times greater than in the case of the present invention.

3 and 4 show specific examples of optical pickups employing the adjustment method of the present invention. Fig. 3 is a perspective view of a spacer used in the present invention, Fig. 3A is a cylindrical spacer, Fig. 3B is a rectangular parallelepiped spacer, and each spacer has a through hole formed therein for passing a screw. be. Various values of the thickness H of each spacer are prepared in advance. FIG. 4 is a diagram in which three spacers shown in FIG. 3A are assembled into an optical pickup. FIG. 4(A) is a front sectional view, and FIG. 4(B) is a plan view.

Three screw holes 11 are formed in the base 3, and the base 3 is firmly fixed to the main body 2 with screws 10 via spacers 6 for each screw hole. A pillar 12 is fixed to the base 3, and a lens holder 14 in which the objective lens 1 is incorporated is supported by four wires 13 to the pillar 12. The objective lens 1 is driven for focusing and tracking by electromagnetic driving means (not shown) installed around the lens holder 14. An optical system 15 for detecting information signals and the like is fixed to the main body 2, and a light beam directed from the objective lens 1 to the optical system 15 is incident through light entrance holes 16 and 17 formed in the base 3 and the main body 2, respectively. Ru.

In addition to the three installation positions of the spacers of the present invention as described above, two spacers 6 may be interposed on the base 3 so as to sandwich the light input column 6B as shown in FIG. In this case, a rectangular parallelepiped spacer shown in FIG. 3B is used.

That is, the number of spacers may be at least two or more.

In this embodiment, the reference Lm 4 has been described as a straight line perpendicular to the upper surface of the main body 2, but such a straight line does not necessarily have to be used as the reference line.

〔Effect of the invention〕

As explained above, according to the present invention, when adjusting the tilt angle of the optical axis of the objective lens, a spacer with an appropriate thickness is selected from several types of spacers with different thicknesses prepared in advance, and the bottom surface of the base is Since the angle of the lens optical axis is adjusted around the intersection O of the lens optical axis and the lens optical axis, the angle adjustment has the effect that the amount of displacement of the objective lens in the optical axis direction can be made extremely small. Furthermore, the angle adjustment is extremely easy because it is only necessary to interpose washers at at least two locations between the base and the main body.

[Brief explanation of drawings]

Fig. 1 is a principle diagram for explaining the objective lens optical axis adjustment method of the present invention, Fig. 2 is a principle diagram for explaining the conventional objective lens optical axis adjustment method, and Fig. 3 is a principle diagram for explaining the objective lens optical axis adjustment method of the present invention. FIG. 4 is a perspective view of a spacer, FIG. 4 is a diagram showing a specific structure of an optical pickup employing the optical axis adjustment method of the present invention, and FIG. 5 is a diagram showing another embodiment. 1.1'...Objective lens 2...Body 3.3'
...Base 4...Reference line 5...Surface
6-8...Spacer 9...Bottom surface
10... Screw 11... Screw hole 12
...Column 13...Wire 14...Lens holder 15...Optical system 16.17...Light entrance hole tube 1 section (A) θ Fig. 1 (B) Fig. 2 Fig. 3

Claims (1)

[Claims] 1. In a method of adjusting the optical axis by tilting a base integrated with an objective lens of an optical pickup in order to read information recorded on a recording medium, the lower surface of the base and the objective A method for adjusting the optical axis of an objective lens of an optical pickup, characterized in that a desired lens optical axis is set by interposing spacers at at least two places between the base and the main body with the intersection of the lens optical axes as the center of rotation. .