JP2003266450A - Optical element and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reconcile high releasability and high shape precision when a resin layer is molded on a substrate material. <P>SOLUTION: The resin layer 6, to which the shape of the molding surface of a mold 2 is transferred, is formed on the surface of the substrate material 4 to manufacture an optical element 7 that is an integrated body of the substrate material and the resin layer. The difference between the maximum and minimum values of the thickness in the normal line direction of the surface of the substrate material of the resin layer is set to 20-200 μm to mold the resin layer. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for manufacturing a lens having an aspherical surface or an element having a fine shape (irregularities) on the surface thereof, for example, a diffraction grating, a Fresnel lens, an optical disk substrate or the like.

[0002]

2. Description of the Related Art Optical element manufacturing methods include glass grinding, polishing, precision molding using a mold,
There are methods such as injection molding and press molding of thermoplastic resin, which are properly used depending on the function, cost, required accuracy, and the like.

For example, in the case of a lens of an image forming system used for a camera or the like, a spherical lens is an economically advantageous method of grinding and polishing, which has little performance deterioration due to environmental changes such as temperature and humidity. Mainly used for aspherical lenses, a method of precision molding of glass using a mold is mainly used. Even in cameras, lenses used for viewfinders are not required to have excellent imaging performance, and are often manufactured by resin injection molding from the viewpoint of cost.

Further, in an aspherical lens having a diameter of 30 mm or more and an optical element having fine irregularities on the surface, a required layer is formed by molding a thin layer of a light energy curable resin on a glass substrate and curing the resin. A method of forming a surface profile is used.

In the case of a large aspherical lens, the precision of shape is deteriorated in the precision molding of glass, and in order to secure the precision, the molding time becomes long and the cost becomes high. Even in the case of an optical element having a fine concavo-convex shape, it cannot be manufactured in glass because the concavo-convex portion is destroyed at the time of mold release, and it is indispensable to manufacture it with a resin. The influence is reduced by the above-mentioned method in which the resin portion is formed into a thin layer.

Regarding the molding of this light energy curable resin, in JP-A-8-286003, the unevenness of the resin layer (the maximum thickness of the resin layer in the direction parallel to the central axis is tmax,
By setting the radius of curvature of the base material such that tmax / tmin when the minimum thickness is tmin is within 1.5 times the minimum thickness, the stress in the resin during curing is reduced, and A method has been proposed in which the amount of shape change at the time of change is reduced.

[0007]

In the molding of a light energy curing type resin, if there is a large difference in the resin thickness in the direction of the normal to the base material, the shape accuracy deteriorates. On the other hand, Japanese Patent Laid-Open No. 8-286003 discloses a method of reducing the stress in the resin during curing by reducing the thickness deviation, but here, the resin thickness on the central axis is set. Due to this, there is a limit to the lower limit of the thickness deviation, and the required shape accuracy may not be obtained. Further, if the thickness deviation is too small, the mold releasability deteriorates, and the resin is cracked or deformed. If a mold release agent is used to prevent this, the durability of the mold is reduced.

Therefore, the present invention has been made in view of the above-mentioned problems, and an object thereof is to achieve both good releasability and good shape accuracy when molding a resin layer on a substrate. Is.

[0009]

[Means for Solving the Problems]
In order to achieve the object, the method for producing an optical element according to the present invention is such that the base material and the resin layer are formed on the surface of the base material by forming a resin layer on which the shape of the molding surface of the mold is transferred. An optical element manufacturing method for manufacturing an integrated optical element, wherein the difference between the maximum value and the minimum value of the thickness of the resin layer in the normal direction of the substrate surface is set to 20 μm or more and 200 μm or less. Then, the resin layer is molded.

Further, in the method of manufacturing an optical element according to the present invention, the molding surface of the mold has a fine concavo-convex shape having a height of 50 μm or less.

Further, in the method of manufacturing an optical element according to the present invention, the molding surface of the mold has an aspherical shape.

In the method of manufacturing an optical element according to the present invention, the base material is made of glass.

Further, in the method for manufacturing an optical element according to the present invention, the resin forming the resin layer is a light energy curable resin.

The optical element according to the present invention is characterized by being manufactured by the above manufacturing method.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described in detail below.

First, an outline of an embodiment of the present invention will be described.

In the embodiment of the present invention, the difference between the maximum value and the minimum value of the resin thickness in the normal direction of the base material is set to 20 μm or more so that the stress in the normal direction of the base material is generated and the releasability is improved. And the difference between the maximum value and the minimum value of the resin thickness is set to 200 μm or less to reduce the stress distribution and improve the shape accuracy.

The operation will be described with reference to FIG.

When a spherical lens 25 as shown in FIG. 11A (a spherical lens is used for the sake of clarity) is molded, the surface 26a of the resin 26 as shown in FIG. 11B.
When the glass base material 27 having a smaller radius of curvature by the resin thickness is used, stress due to the difference in the resin thickness is not generated, and the difference in shape between the resin surface and the mold is 0.1 μm or less, which is very good. On the other hand, the stress in the normal direction does not work so much on the glass substrate (it is not zero due to the Poisson effect), and a large load is required for release.

On the other hand, the radius of curvature of the glass substrate is shown in FIG.
By adopting 1 (c) or (d), a difference in stress is generated in the normal direction of the glass substrate due to the difference in resin thickness, and mold release is facilitated. However, when the radius of curvature of the glass substrate is largely changed from the radius of curvature of the resin surface as shown in FIG. 11E, the stress due to the difference in shrinkage in the normal direction during curing shrinkage causes
The shape difference from the mold is several μm or more. The mold releasability is very good, but the shape accuracy is deteriorated, and in extreme cases, the mold is released at the time of curing shrinkage. On the other hand, FIG. 11 (c) and (d)
As described above, by setting the difference between the maximum value and the minimum value of the resin thickness to 200 μm or less, it is possible to suppress the deterioration of the shape accuracy to 0.3 μm or less.

Further, in the optical element having fine irregularities on the surface as shown in FIG. 12, the releasability is worse than that of a lens having a smooth surface as shown in FIG. 11, and the irregularities at the time of release are destroyed. Or deformed. Therefore, it is more effective to change the radius of curvature of the glass substrate and improve the releasability due to the stress due to the difference in resin thickness. However, the unevenness is 50μ
If it exceeds m, the effect alone cannot suppress the breakage of the uneven portion.

The optical element molded by the method of the embodiment of the present invention is an optical element which has good releasability, is economical, and has good shape accuracy.

The optical element having fine irregularities on the surface formed by the method of the embodiment of the present invention is an optical element in which the irregularities are not destroyed or deformed.

(First Embodiment) FIG. 1 shows a first embodiment of the present invention.
FIG. 6 is a schematic view showing a method of molding an optical element having a fine shape on its surface according to the embodiment of FIG.

In FIG. 1, 1 is a light energy curable resin dropped on a mold, 2 is a mold used for molding, and the surface has a depth of 10 μm and a pitch of 50 to 4 as shown in an enlarged view of FIG.
The fine concavo-convex is formed in which the surface connecting the peaks of the peaks is 00 μm and is a flat surface. 3 is a dispenser used for dropping, 4 is a glass base material, 5 is a resin press-transferred to a mold,
Reference numeral 6 is a resin layer cured by irradiation with light energy rays (for example, ultraviolet rays), and reference numeral 7 is a molded article in which the resin layer 6 having a fine shape is bonded on the surface of the glass substrate 4.

As shown in FIG. 1A, a predetermined amount of light energy curable resin (hereinafter simply referred to as resin) is dropped on the mold 2 by a dispenser. As shown in FIG. 1B, a glass base material 4 is placed thereon, and pressure is applied by an apparatus (not shown) to transfer the shape of the mold 2 to the resin. At this time, the surface of the glass base material 4 in contact with the resin 5 has a concave radius of curvature 750.
mm, the resin thickness is set to 300 μm at the center, and the outer diameter of φ30 mm is approximately 150 μm.
So that

A silane coupling treatment is applied to the contact surface of the glass substrate 4 with the resin 5 in order to improve the adhesion with the resin. After that, as shown in FIG. 1C, the resin is irradiated with light energy rays (here, ultraviolet rays) through the glass to be cured. Then, as shown in FIG.
A resin is peeled from the mold 2 by applying a force to the periphery of the glass substrate 4 with an apparatus (not shown) to obtain a molded product 7. In mold release,
The mold and the glass were easily peeled off under a pressure of several hundred KPa, and there was no cracking or deformation of the uneven portion, and the shape accuracy was good.

As a comparative example, a glass substrate having a flat contact surface with the resin and a glass substrate having a radius of curvature of 321.5 mm were used, and the resin was dropped at a center thickness of 300 μm. Molding was performed in the same manner as in the first embodiment except that the amount was changed.

With a flat glass substrate, a pressure of several MPa or more was required for mold release, and a part of the uneven portion was lacking. Further, in the case where the radius of curvature is 321.5 mm, the minimum value of the resin thickness is about 50 μm and the film thickness difference is 250 μm in the outer peripheral portion of φ30, the mold release is good, and the uneven portion is not chipped. Although the surface connecting the apexes of the part was a flat surface in the mold, it was deviated from a flat surface of several μm in the molded product.

As described above, by setting the difference between the maximum value and the minimum value of the resin thickness in the normal line direction of the glass substrate to be 150 μm, there is no chipping or deformation of fine irregularities due to poor releasability. It is now possible to mold a resin on a glass substrate with good shape accuracy.

(Second Embodiment) FIG. 3 is a diagram showing a second embodiment of the present invention.

In FIG. 3, 8 is a resin, 9 is a mold used for molding, and the surface has a depth of 10 μ as shown in the enlarged view of FIG.
A fine concavo-convex shape in which the surface connecting the peaks of the peaks is a plane is formed at m and a pitch of 50 to 400 μm. The direction of the saw teeth is opposite to that of the mold of the first embodiment. Reference numeral 10 is a glass base material, and 11 is a molded product in which a resin layer 8'having a fine shape is bonded to the surface of the glass base material 10. The center thickness of the resin is 300 μm, and the outer peripheral portion of φ30 mm has a thickness of about 150 μm.

Molding was performed using the mold 9 and the glass substrate 10 in the same steps as in the first embodiment. However, in mold release, the mold and resin were easily peeled off at a pressure of several hundred KPa to several MPa, resulting in unevenness. There was no crack or deformation of the part, and the shape accuracy was good. However, the force required for mold release was slightly larger than that in the first embodiment. This is because, in this embodiment, the fine shape of the mold surface is such that a vertical surface is sandwiched during resin shrinkage as compared with the first embodiment, and the mold is more difficult to release. .

Here, the glass substrate 12 is shaped as shown in FIG. 5, and the resin thickness is 150 μm at the center and 30 at the outer peripheral portion.
When it was set to 0 μm, the mold release was performed at several tens of KPa, and the mold releasability was further improved. This is probably because the periphery of the resin is thick and a large tensile stress is applied to the periphery, which facilitates mold release.

As described above, by forming a difference in the resin thickness in the normal direction of the glass substrate, there is no chipping or deformation of the fine irregularities, and the resin can be molded into a glass substrate having good shape accuracy. It will be possible. Further, by providing the resin thickness so that the peripheral portion is thicker than the central portion, the releasability is further improved.

(Third Embodiment) FIG. 6 is a diagram showing a third embodiment of the present invention.

In FIG. 6, 13 is a resin, 14 is a mold used for molding, and the surface has a standard radius of curvature 24 as shown in FIG.
It has an aspherical shape with a portion at a maximum distance of 10 μm from the center of the radius of curvature from mm. Reference numeral 15 is a glass base material, and the contact surface with the resin is polished to have a radius of curvature of 23.768 mm. Reference numeral 16 is a molded product in which a resin layer 13 ′ having an aspherical shape is bonded to the surface of the glass base material 15. The thickness of the resin is 300 μm in the central portion, and the thickness in the normal direction of the glass substrate is the minimum at the outermost circumference φ30 mm, which is 180 μm. Molding was performed using the mold 14 and the glass base material 15 in the same process as in the first embodiment. In the mold release, the mold and the resin were easily separated at a pressure of several hundred KPa, and the shape accuracy was good, with a deviation from the mold of 0.1 μm.

As a comparative example, a glass substrate has a radius of curvature of 2
Molding was carried out in the same manner as in the third embodiment except that 3.697 mm and 23.823 mm were used and the amount of resin at the time of dropping was changed so that the center thickness of the resin was 300 μm.

In the case where the radius of curvature is 23.697 mm, the thickness of the glass substrate in the normal direction is 300 μm at the center, and the maximum is 315 μm at the aspherical portion 10 μm away from the spherical surface in the center direction with a radius of curvature of 24 mm. The thickness difference is 15 μm. In the case of a radius of curvature of 23.823 mm, the maximum thickness in the normal direction of the glass substrate is 300 μm at the center, the minimum is 80 μm at the outermost periphery, and the resin thickness difference is 220 μm.

With a glass substrate having a radius of curvature of 23.697 mm, a pressure of several MPa or more was required for mold release, and a part of the resin remained in the mold. Further, the mold having a radius of curvature of 23.823 mm had a good mold release and had no irregularities, but the shape was deviated from the mold by 2 μm.

As described above, by setting the difference between the maximum value and the minimum value of the resin thickness in the normal direction of the glass base material to 120 μm, the resin does not remain in the mold due to the poor releasability.
It has become possible to mold a resin on a glass substrate with good shape accuracy.

(Fourth Embodiment) FIG. 8 shows a fourth embodiment of the present invention.
It is a figure which shows the embodiment of.

In FIG. 8, 17 is a resin, 18 is a mold used for molding, and the surface has a standard radius of curvature 50 as shown in FIG.
It has an aspherical shape with a portion distant from the center of the radius of curvature by 150 μm at the maximum. Reference numeral 19 denotes a glass base material, and the contact surface with the resin 17 is polished to have a radius of curvature of 49.867 mm. Reference numeral 20 is a molded product in which a resin layer 17 'having an aspherical shape is bonded to the surface of the glass base material 19.

The resin was molded so that the thickness of the resin was 100 μm at the center, and the thickness of the resin in the normal direction of the glass substrate was 100 μm at the center and 150 μm away from the spherical surface in the center direction with a radius of curvature of 50 mm at the maximum. The aspherical surface portion has a thickness of 280 μm.

Molding was performed using the mold 18 and the glass 19 in the same steps as in the first embodiment. In the mold release, the mold and the resin were easily separated at a pressure of several hundred KPa, and the shape accuracy was good, with a deviation from the mold of 0.1 μm.

As described above, by setting the difference between the maximum value and the minimum value of the resin thickness in the normal direction of the glass substrate to 180 μm, the resin does not remain in the mold due to poor releasability.
It has become possible to mold a resin on a glass substrate with good shape accuracy.

(Fifth Embodiment) FIG. 10 is a diagram showing a fifth embodiment of the present invention.

In FIG. 10, 21 is a resin, 22 is a mold used for molding, and 1.44X ² + (Y-
30) ² = 30 ^{2 having} an elliptical surface. Reference numeral 23 is a glass base material, and 24 is a molded product in which a resin layer 21 ′ having an elliptical shape is bonded to the surface of the glass base material 23. The thickness of the glass base material 23 in the normal direction is 300 μm at the center, and φ
The outermost circumference of 40 mm is a minimum of 200 μm.

Molding was performed using the mold 22 and the glass 23 in the same process as in the first embodiment. In mold release, there are hundreds of molds and resins
It was easily peeled off under a pressure of KPa, and the shape accuracy was good with a deviation from the mold of 0.1 μm.

As a comparative example, the radius of curvature of the glass substrate is 2
Molding was performed in the same manner as in the fifth embodiment, except that the one having a diameter of 2.386 mm and the one having a diameter of 22.807 mm were used and the amount of resin at the time of dropping was changed so that the center thickness of the resin was 300 μm.

The radius of curvature of 22.386 mm is 290 μm at the minimum thickness in the normal direction of the glass substrate and the resin thickness difference is 10 μm, and the radius of curvature of 22.807 mm is in the normal direction of the glass substrate. The minimum thickness is 70 μm and the resin thickness difference is 230 μm.

With a glass substrate having a radius of curvature of 22.386 mm, a pressure of several MPa or more was required for mold release, and a part of the resin remained in the mold. Further, the mold having a radius of curvature of 22.807 mm had a good mold release and had no irregularities, but the shape was deviated from the mold by 3 μm.

When a glass base material having a radius of curvature of 22.386 mm was used to perform molding in the same manner so that the resin center portion was 500 μm, it was easily released and the shape was good with a deviation of 0.2 μm from the mold. Met. By changing the resin thickness, the maximum value of the resin thickness in the normal direction of the glass substrate is 500 μm in the central part, and the minimum value is 3 mm at the outer peripheral part φ40 mm.
It is considered that the difference became 115 μm at 85 μm.

As described above, by setting the difference between the maximum value and the minimum value of the resin thickness in the normal direction of the glass base material to 100 μm, the resin does not remain in the mold due to poor releasability.
It has become possible to mold a resin on a glass substrate with good shape accuracy. Even if the resin thickness is changed without changing the radius of curvature of the glass base material, the difference between the maximum value and the minimum value of the resin thickness in the normal direction of the glass base material is set to 20 μm or more and 200 μm or less. It was found that the moldability and shape accuracy could be improved.

[0055]

As described above, according to the present invention, it is possible to form a light energy curable resin having a good mold releasability and a good shape accuracy on a glass substrate by bonding, and having a fine uneven portion. It is possible to suppress the chipping of the uneven portion and the residual resin in the mold.

[Brief description of drawings]

FIG. 1 is a schematic view showing a molding process in a first embodiment.

FIG. 2 is a diagram showing a fine shape of a mold surface used in the first embodiment.

FIG. 3 is a schematic view showing a mold, a glass base material and a molded product used in the second embodiment.

FIG. 4 is a view showing a fine shape of a mold surface used in the second embodiment.

FIG. 5 is a schematic view showing another glass substrate used in the second embodiment.

FIG. 6 is a schematic view showing a mold, a glass base material and a molded product used in the third embodiment.

FIG. 7 is a diagram showing a shape of a mold surface used in a third embodiment.

FIG. 8 is a schematic view showing a mold, a glass base material and a molded product used in the fourth embodiment.

FIG. 9 is a view showing the shape of the mold surface used in the fourth embodiment.

FIG. 10 is a schematic view showing a mold, a glass base material and a molded product used in the fifth embodiment.

FIG. 11 is a diagram showing a combination of a glass base material and a resin thickness for explaining the operation of the embodiment of the present invention.

FIG. 12 is a schematic view of an optical element having a fine shape on the surface.

[Explanation of symbols]

1, 5, 6, 8, 13, 17, 21, 21, 26, 28, 3
0,32 Light energy curable resin 2,9,14,18,22 type 3 Dispenser 4,10,12,15,19,23,27,29,3
1,33 Glass base material 7,11,16,20,24 Molded article 25,34 Optical element

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G02B 5/18 G02B 5/18 // B29K 101: 10 B29K 101: 10 105: 20 105: 20 B29L 11: 00 B29L 11:00 F-term (reference) 2H049 AA03 AA33 AA40 AA45 AA70 4F202 AA44 AF01 AG03 AG05 AG26 AH73 CA09 CA11 CB01 CB13 CD02 CD18 CK11 CL02 CQ03 4F204 AA44 AD04 AG03 AG05 AG26 AH73 EA03 EF01 EB03 EA03 EA03 EA03 EA03 EA04 EA04

Claims (6)

[Claims] 1. An optical element for producing an optical element in which the base material and the resin layer are integrated by forming a resin layer on the surface of the base material, on which the shape of the molding surface of the mold is transferred. And a difference between the maximum value and the minimum value of the thickness of the resin layer in the normal direction of the surface of the base material is set to 20 μm or more and 200 μm or less,
A method for manufacturing an optical element, which comprises molding the resin layer. 2. The method of manufacturing an optical element according to claim 1, wherein the molding surface of the mold has a fine concavo-convex shape having a height of 50 μm or less. 3. The method of manufacturing an optical element according to claim 1, wherein the molding surface of the mold has an aspherical shape. 4. The method for manufacturing an optical element according to claim 1, wherein the base material is made of glass. 5. The method of manufacturing an optical element according to claim 1, wherein the resin forming the resin layer is a light energy curable resin. 6. An optical element manufactured by the manufacturing method according to claim 1.