JPH04330Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to a lens support mechanism installed in a compact disc player, etc., and in particular to a lens support for positioning a lens such as an objective lens in a lens holder and fixing it by adhesive. Regarding the mechanism.

[Background of the idea]

FIG. 5 schematically shows the structure of an optical pickup installed in a compact disc player.

A detection beam emitted from a laser diode 1 passes through a beam splitter 2 and becomes a parallel beam at a collimating lens 3. The detection beam is then focused by an objective lens provided in the lens holder 4, and a minute spot of the beam is formed on the recording surface of the optical disk D. Further, the beam reflected from the recording surface of the optical disk D passes through the objective lens and the collimating lens 3, returns, and is reflected by the beam splitter 2 in the right angle direction. The intensity of the beam detected by the pin photodiode 6 allows reading of digital information recorded in a pit shape on the optical disk D.

FIG. 3 is a sectional view showing the internal structure of a conventional lens holder 4. As shown in FIG.

An objective lens 10 is housed within the lens holder 4. This objective lens 10 is a glass press lens or a plastic molded lens. The objective lens 10 shown in FIG. 3 is a menicus lens, and its lower surface 10a is a spherical or aspherical convex curved surface, and the upper surface 10b is a spherical or aspherical concave curved surface.

The lens holder 4 has an opening 4a formed in its inner diameter. This opening 4a is formed to have a smaller diameter φ than the lower end hole 4b due to the presence of the step 4c. The parallel beam passing through the collimating lens 3 shown in FIG.
Further, in the conventional lens holder 4, the opening 4a
The side edge of the lens is the positioning corner A,
The objective lens 10 is positioned by the convex curved portion of the lower surface 10a of the objective lens 10 coming into contact with this positioning corner A, and the objective lens 10 is positioned.
0 and the lens holder 4 are adhesively fixed to each other with an ultraviolet curing adhesive.

[Problem that the invention attempts to solve]

In the lens holder 4 having the structure shown in FIG. 3, when the objective lens 10 is fixed, the curved part of the lower surface 10a is slid against the positioning corner A, and the objective lens 10 is
Generally, the inclination angle of the optical axis of the objective lens 10 is adjusted and fixed by moving the lens 0 in the direction of the arrow α. This adjustment is mainly performed to make the optical axis of the objective lens 10 accurately perpendicular to the recording surface of the optical disk D.

For this adjustment work, first, the positioning corner A
An ultraviolet curable adhesive 11 is applied to the outer part of the holder (see FIG. 4). Then, the objective lens 10 is moved in the direction of the arrow α, and when it is at the correct position, the adhesive 11 is irradiated with ultraviolet rays to harden the adhesive 11.

However, when moving the objective lens 10 in the direction of the arrow α with the adhesive 11 applied, the adhesive 11 adhering to the surface of the lower surface 10a of the lens causes the objective lens 10 to move as shown in FIG. As a result, it may protrude further toward the center than the positioning corner A. If you irradiate ultraviolet rays in this state, the adhesive 1
The protruding portion of 1 will be cured. As a result, the effective diameter of the objective lens 10 is substantially narrowed by the area X of the adhesive 11 that has protruded, which even affects the numerical aperture of the objective lens 10.

In addition, in FIG. 3, a flange 4d protruding in the inner diameter direction may be formed at the lower end portion of the opening 4a as shown by a dashed line, and the diameter of the incident beam may be determined by the inner diameter of this flange 4d. Even in this case, if the protruding range X of the adhesive 11 becomes large, the adhesive 11 will protrude inward from the aperture diameter of the beam due to the flange 4d, and the above-mentioned problem will similarly occur.

The present invention solves the above-mentioned conventional problems by preventing the adhesive from protruding into the aperture through which the detection beam passes when adjusting the position of the lens, and substantially narrowing the effective diameter of the lens. This is to prevent this from happening.

[Structure of the idea to solve the problem]

In the lens support mechanism of the optical pickup according to the present invention, a hole is formed in the lens holder through which the detection beam is incident, and a positioning corner shaped along the circumference is formed at the opening of this hole, so that the convex curved surface of the lens is formed. The lens can be centered by coming into contact with this positioning corner, and a step is formed in the direction opposite to the lens from this positioning corner, so that it is perpendicular to the optical axis of the lens and circular with respect to the center of the hole. A shaped flat surface is provided, and a space for holding an adhesive is formed between this flat surface and the convex curved surface of the lens.

[Effect of invention]

In this invention, even if the lens is moved to adjust the tilt of the optical axis after applying adhesive to the outer periphery of the positioning corner, the adhesive will follow the curved surface of the lens and protrude inside the positioning corner. The liquid remains in the space inside the step and cannot leak into the opening of the holder. Therefore, after the adhesive hardens, the adhesive no longer adheres to the curved surface portion of the lens located within the opening of the holder.

[Example of idea]

Embodiments of the present invention will be described below with reference to FIGS. 1 and 2.

FIG. 1 is a sectional view showing a lens support mechanism of an optical pickup according to the present invention, and FIG. 2 is a partially enlarged view thereof.

Reference numeral 14 is a lens holder. This lens holder 14 is arranged at the tip of the collimating lens 3 in the optical pickup of the compact disc player shown in FIG. The objective lens 10 supported within the lens holder 14 is for converging the detection beam that has been made into a parallel beam by the collimating lens 3 to form a minute spot of the beam on the recording surface of the optical disk D. It is.

The objective lens 10 has a lower surface 10a that is a spherical or aspherical convex curved surface, and an upper surface 10b that is a spherical or aspherical concave curved surface.

The lens holder 14 has a hole 14d formed in its center, the upper part of which protrudes in the inner diameter direction, and an opening 14a formed by its inner surface. The detection beam irradiated into the lens holder 14 is condensed into a light beam having a diameter φ by the aperture 14a.

Further, inside the lens holder 14, a space 14b is formed that extends radially outward from the upper end (lens side end) of the opening 14a. A step 14c is formed at the outer peripheral end of this space 14b, and the top of this step 14c serves as a positioning corner A for the lens.

Next, the objective lens 1 relative to the lens holder 14 is
0 positioning and bonding work will be explained.

The convex curved portion of the lower surface 10a of the objective lens 10 is
It is installed on the positioning corner A within the lens holder 14. When the objective lens 10 is installed, the space 1
A slight gap is formed between the left corner B of 4b and the objective lens 10. Further, on the outside of the positioning corner A, an ultraviolet curing adhesive 1 is applied between the lower surface 10a of the objective lens 10 and the lens holder 14.
1 is applied.

Then, by sliding the lower surface 10a and the positioning corner A to move the objective lens 10 in the α direction, the angle of inclination of the optical axis of the objective lens 10 is adjusted. In this adjustment work, a dummy optical disk is used so that the optical axis of the objective lens 10 is accurately perpendicular to the recording surface of the optical disk.

In this adjustment work, when the objective lens 10 is moved in the α direction, the adhesive 11 is applied to the objective lens 10.
inside the positioning corner A along the lower surface 10a of the
It will stick out. However, a space 14b is formed inside the positioning corner A,
In addition, since the gap between the corner B on the center side of the space 14b and the lower surface 10a of the lens is minute, the adhesive 1 protrudes inside the positioning corner A.
1 is retained in the space 14b by capillarity and does not protrude inside the corner B, that is, into the opening 14a.

After determining the position of the objective lens 10, the adhesive 11
is irradiated with ultraviolet rays to harden the adhesive 11 and fix the objective lens 10.

Since the adhesive 11 does not protrude into the aperture 14a, the detection beam entering the objective lens 10 is not obstructed by the adhesive 11, and the detection beam is effective over the entire range of the aperture diameter φ formed by the aperture 14a. .

In the illustrated embodiment, the positioning corner A in the lens holder 14 is formed over the entire length in the circumferential direction, but it is also possible to form the positioning corner A intermittently.

[Effect of idea]

As described above, according to the present invention, even if the inclination of the optical axis of the objective lens is adjusted after applying the adhesive, the adhesive will not protrude into the opening of the lens holder. The detection beam incident on the objective lens is thus no longer obstructed by the adhesive over the entire area of the aperture, and the effective diameter of the objective lens is no longer substantially narrowed and the numerical aperture is no longer affected.

[Brief explanation of drawings]

Figures 1 and 2 show an embodiment of the present invention. Figure 1 is a sectional view showing the lens support mechanism of an optical pickup, Figure 2 is a partially enlarged view, and Figure 3 is a conventional one. A cross-sectional view showing the lens support mechanism of the optical pickup; Fig. 4 is a partially enlarged view;
The figure is a block diagram of an optical pickup installed in a compact disc player. 10... Lens, 10a... Convex curved surface of the lens,
11... Adhesive, 14... Lens holder, 14a
...Opening, 14b...Space, A...Positioning corner.

Claims (1)

[Scope of utility model registration request] A hole is formed in the lens holder through which the detection beam is incident, and a positioning corner shaped along the circumference is formed at the opening of this hole, and the convex curved surface of the lens comes into contact with this positioning corner, thereby centering the lens. In addition, a step is formed from this positioning corner in a direction opposite to the lens, and a plane is provided which is orthogonal to the optical axis of the lens and formed in a ring shape with respect to the center of the hole. A lens support mechanism for an optical pick-up, characterized in that a space for holding an adhesive is formed between the lens and the convex curved surface of the lens.