JPH0614258Y2 - Fixing structure of objective lens for optical pickup - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a fixing structure for an objective lens for an optical pickup.

[Conventional technology]

As an objective lens for an optical pickup, for example, in order to accurately position each signal on a CD (compact disc) rotating at high speed, an actuator to which the objective lens is bonded must respond at high speed. Therefore, the objective lens has an instantaneous maximum of 300 g (g = 9.8 m / s)
Acceleration of gravity may reach to even. Further, a fixing structure that maintains sufficient strength under various environments is required.

However, the conventional objective lens for an optical pickup is made of glass, and the material thereof is hard and has high mechanical strength.

For this reason, it is not necessary to make a subtle modification to the structure for fixing the objective lens to the holder, and it suffices to firmly bond and fix the outer peripheral portion of the objective lens to the metal or synthetic resin holder with an adhesive such as epoxy resin. .

[Problems to be solved by the invention]

However, recently, an integrally molded objective lens made of synthetic resin, which can be sufficiently used as an objective lens for an optical pickup, has been provided to the market, and it has greatly contributed to the cost reduction of the objective lens. Since it is a resin, it is soft and has low mechanical strength, so if it is bonded and fixed like a glass lens, the lens will be distorted, and the optical characteristics of the lens will deteriorate to the point where it cannot be used. There was a problem that it would end up.

The present invention has been made in order to solve such a problem, and an object thereof is to obtain a fixing structure of an objective lens for an optical pickup, which is free from distortion in a lens portion and has a large fixing strength.

[Means for solving problems]

The fixing structure of the objective lens for an optical pickup according to the present invention is a cylindrical portion integrally molded of synthetic resin and provided on the outer periphery of the lens portion so as to project in the optical axis direction. An objective lens having a collar portion formed on the upper surface, a standing wall portion formed to face the outer peripheral surface portion of the collar portion, a first receiving portion for receiving the lower surface of the collar portion, and an outer peripheral surface portion of the cylindrical portion on the lower surface side of the collar portion. And a lens holder having a second receiving portion for receiving, forming a chamfered portion at a corner portion between the first receiving portion and the second receiving portion, and between the standing wall portion and the outer peripheral surface portion of the flange portion. The adhesive layer is formed.

[Action]

In this invention, since the adhesive layer is formed between the outer peripheral surface of the collar portion separated from the lens portion and the inner wall surface of the standing wall portion provided on the lens holder facing the collar portion, the lens layer The strain is unlikely to be applied to the part, and the adhesive structure can utilize the tensile breaking force with a strong adhesive force.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS.

In the figure, 1 is an integrally molded objective lens made of acrylic synthetic resin, 2 is a lens portion thereof, and 3 is provided so as to project in the optical axis direction, and protects this lens portion 2 from scratches due to external action, A cylindrical portion 4 serving as a reference portion for positioning the lens portion 2 in the radial direction, a substantially disc-shaped collar portion provided on the cylindrical portion 3 so as to project in the radial direction of the lens portion 2,
Reference numeral 5 denotes a lower surface portion of the collar portion 4 serving as a reference portion for positioning the lens portion 2 in the optical axis direction, 6 denotes an outer peripheral surface portion of the collar portion 4, and 7 denotes the collar portion 4.
Is the upper surface of the.

Reference numeral 8 is a gate portion, and after molding, unnecessary portions are removed by heat.

Reference numeral 10 denotes a lens holder to which a control coil (not shown) or the like is mounted as an actuator.

Reference numeral 11 denotes a standing wall portion which is slightly larger than the collar portion 4 and is formed so as to be one step lower than the upper surface portion 7 in the mounted state, and 12 is a notch portion as a pair of escape portions provided corresponding to the gate portion 8. In view of known characteristics, the lens holder 10 is formed in a fixed direction.

A first receiving portion 13 receives the lower surface portion 5 and positions the lens portion 2 with respect to the lens holder 10 in the optical axis direction.
Is a second receiving portion that receives the cylindrical portion 3 and positions the lens portion 2 in the radial direction with respect to the lens holder 10. The second receiving portion is formed to be slightly larger than the outer shape of the cylindrical portion 3, and the cylindrical portion 3 is loosely fitted. Hold on.

Reference numeral 15 denotes a surface trig portion provided in a corner portion formed by the first receiving portion 13 and the second receiving portion 14, and in this case, it is formed by a C (chamfer) surface trig with about C0.2.

Reference numeral 16 is an upper end surface portion of the standing wall portion 11, and 17 is an inner wall surface.

20 is an aperture on the lower surface side of the objective lens 1 that regulates the incident light beam diameter to a predetermined size, 21 is a gap formed between the outer peripheral surface portion 6 of the collar portion 4 and the inner wall surface portion 17 of the standing wall portion 11, and 22 is an adhesive. Here, it is an ultraviolet curable adhesive.

Reference numeral 24 denotes a gate residue that remains in a convex shape on the gate portion 8 after thermal cutting. The adhesive 22 is applied in four symmetrical positions.

FIG. 4 is a diagram showing a case where the adhesive 22 is significantly permeated, and occurs when the adhesive 22 is applied in an excessive amount or when the adhesive 22 is left unnecessarily for a long time, and therefore the adhesive 22 penetrates deeply.

The adhesive 22 is prevented from penetrating in the gap B formed by the lower surface portion 5 of the collar portion 4, the cylindrical portion 3, the first receiving portion 13 and the surface receiving portion 15 between the second receiving portion 14, The movement is stopped for a considerably long time, and does not enter into the loose fitting holding portion formed by the cylindrical portion 3 and the second receiving portion 14.

Next, the assembly will be described. The objective lens 1 is inserted into the standing wall portion 11 of the holder 10 and the upper surface portion 7 of the collar portion 4 is inserted.
Is pressed to bring the lower surface portion 5 of the collar portion 4 into close contact with the first receiving portion 13.

Then, an appropriate amount of the ultraviolet curable adhesive 22 is applied so as to straddle the upper surface portion 7 of the collar portion 4 and the upper end surface portion 16 of the standing wall portion 11, and the adhesive 22 is cured in the gap 21 by curing with ultraviolet light. Individualize.

In the case of this structure, the adhesive 2
When 2 is applied, as a result, the adhesive is bonded in four places in the gap 21 by the adhesive 22, and the objective lens 1 can obtain a sufficient adhesive force in the direction of A in FIG.

In addition, since there are few adhesion points at four places, and since the adhesion is fixed at a position far from the lens portion 2, distortion is unlikely to be applied to the lens portion 2.

Further, in the case of this embodiment, since the notch portion 12 is provided corresponding to the gate portion 8, for example, as shown in FIG.
Even if the gate dregs 24 remain in a convex shape due to poor processing, the mounting of the objective lens 1 is not affected at all, and since the pair of notches 12 are provided at symmetrical positions, the objective lens 11 is adhered. There is also an advantage that the collar portion 4 corresponding to these cutout portions 12 can be easily assembled by sandwiching it from both sides and grasping.

Further, as shown in FIG. 4, since the adhesive agent 22 is prevented from flowing into the cylindrical portion 3 close to the lens portion 2 at the gap portion B at the actual working level, the distortion to the lens portion 2 is prevented. Can be said to be extremely safe.

The standing wall portion 11 is not limited to the shape divided into two as in this embodiment, but may be formed in a shape corresponding to the flange portion 4 of the objective lens 1 if necessary, and the cutout portion 12 is also formed. It goes without saying that any shape that allows the gate portion 8 to escape is sufficient.

Furthermore, if it is necessary for the chamfered portion 15 as well, it is sufficient that the chamfered portion 15 has a shape that prevents the adhesive 22 from permeating.

[Effect of device]

As described above, the present invention is an integrally molded synthetic resin having a cylindrical portion protruding in the optical axis direction on the outer periphery of the lens portion and a flange portion formed on the outer periphery of the cylindrical portion in a substantially flat plate shape in the radial direction. An objective lens, a standing wall portion formed to face the outer peripheral end surface of the collar portion, a first receiving portion for receiving the lower surface of the collar portion, and a second receiving portion for receiving the outer peripheral surface of the tubular portion on the lower surface side of the collar portion. And a lens holder, and a corner portion formed by the first receiving portion and the second receiving portion is provided with a flat surface portion, and an adhesive layer is formed between the standing wall portion and the outer peripheral surface portion of the flange portion. Therefore, in fixing the objective lens, since it is adhesively fixed at a position distant from the lens portion, reliable adhesive fixation with less influence of distortion can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part showing an embodiment of a structure for fixing an objective lens according to the present invention, FIG. 2 is a plan view thereof, FIG. 3 is an exploded perspective view thereof, and FIG. It is an important section sectional view showing a case. In the figure, 1 is an objective lens, 3 is a cylindrical portion, 4 is a collar portion, 5 is a lower surface portion, 8 is a gate portion, 10 is a holder, 11 is a standing wall portion,
12 is a cutout portion, 13 is a first receiving portion, 14 is a second receiving portion,
Reference numeral 15 is a flat surface portion, and 22 is an adhesive.

Claims (2)

[Scope of utility model registration request] 1. A lens part integrally molded of synthetic resin, a cylindrical part projecting in the optical axis direction on the outer circumference of the lens part, and a flange formed on the outer circumference of the cylindrical part in a substantially flat plate shape in the radial direction. An objective lens having a portion, a standing wall portion formed to face the outer peripheral surface portion of the flange portion, a first receiving portion for receiving the lower surface of the collar portion, and a second receiving portion for the outer peripheral surface portion of the tubular portion on the lower surface side of the collar portion. A lens holder having a receiving portion, and forming a chamfered portion at a corner portion between the first receiving portion and the second receiving portion, and between the inner wall surface of the standing wall portion and the outer peripheral surface portion of the collar portion. An objective lens fixing structure for an optical pickup, characterized in that an adhesive layer is formed on the. 2. The optical pickup according to claim 1, wherein the collar portion has a molded gate portion, and the standing wall portion has a notch portion corresponding to the gate portion. Fixed structure of the objective lens.