JP2003222708A - Optical element and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical element improving durability of a mold by reducing demolding force in starting demolding, controlling a start point and a direction of the demolding, and preventing peeling, deformation and breakage of a resin from a glass board. <P>SOLUTION: The optical element forming a light energy curable resin has a required shape on a base material by demolding a light energy curable resin after curing it by shape transfer and light irradiation by using the mold. Two regions different in the demolding exist on a resin/mold interface, the inside has an inferior demolding region, the outside has a good demolding region, and the optical element has a projection-like shape in viewing from an orthogonal direction to a base material face of an outer peripheral part of the inferior demolding region. <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 lens having an aspherical surface, an optical element having a fine shape (unevenness) on the surface thereof, such as a diffraction grating, a Fresnel lens, an optical disk substrate, and a method for manufacturing the same.

[0002]

2. Description of the Related Art The method of manufacturing an optical element includes grinding glass,
There are polishing, precision molding using a mold, injection molding of thermoplastic resin, press molding, etc., and they are used properly depending on the function, cost, required accuracy, etc. For example, for aspherical lenses used for imaging lenses used in cameras, etc., aspherical lenses are manufactured by grinding and polishing glass, which has less performance deterioration due to environmental changes in temperature and humidity, and is economically advantageous. Is manufactured by precision molding of glass using a mold. Since lenses used for viewfinders in cameras are not required to have excellent imaging performance, they are manufactured by resin injection molding in terms 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. The precision of shape of a large aspherical lens deteriorates in precision molding of glass, and if the precision is to be secured, the molding time becomes long and the cost becomes high. Even optical elements with fine irregularities cannot be manufactured with glass because the irregularities are destroyed during mold release,
Manufacturing with resin is essential, but if the entire element is resin,
The above-mentioned method, in which the performance is largely deteriorated due to environmental fluctuations and the resin portion is made into a thin layer, reduces its influence.

As a mold releasing method in the molding of this light energy curable resin, for example, JP-A-63-131352 is used.
Release by protrusion of No. JP-A No. 01-152015, release using heat stress due to heating and cooling, JP-A-62-2015
-117154 vibration causes mold release. Examples of the mold releasability improvement include a mold having good mold releasability of Japanese Patent No. 2680175, a mold treated with a mold releasing agent of Japanese Patent No. 3006199, and a resin of Japanese Patent Application Laid-Open No. 04-254801 with an internal release agent. Proposals have been made to include it.

[0005]

In the molding of light energy curable resin, if the release is hindered, the resin peels from the base material, the surface shape of the resin changes, or the surface is fine. In an element having unevenness, the unevenness may be destroyed. Further, not only the shape accuracy is adversely affected, but also the releasability greatly affects the cost in terms of production tact (molding time) and mold durability. The above-mentioned proposals have been made to improve the releasability as described above, but the above three cases are related to the load method for the releasability and are not intended to reduce the force required for the releasability. Therefore, considerable stress acts on the resin / mold interface at the time of mold release, and not all of the above problems are solved.

Also, the latter three cases are reduction of the releasing force itself,
Improvements in mold surface materials and resin compositions have been considered.

However, if the mold surface material has a good releasing property,
Like Teflon (registered trademark), it has a poor surface roughness and cannot be used for optical applications, and the release agent also has a short durability, and adversely affects the appearance and the environmental durability of the resin after molding. In addition, in the resin composition improvement, the releasability with the internal release agent is improved, but this also reduces the mold durability due to mold contamination, the appearance of the molded product, the environmental durability of the resin after molding. Adversely affect.

The present invention has been made in view of the above problems, and its object is to reduce the releasing force at the start of releasing, and to set the starting point of releasing and the direction of releasing. An object of the present invention is to provide an optical element that can be controlled and can prevent the resin from peeling off, deforming, and breaking from the glass substrate and improve the durability of the mold, and a method for manufacturing the same.

[0009]

In order to achieve the above object, the present invention provides a light energy curable resin on a substrate by transferring a shape using a mold, curing by light irradiation, and then releasing. In an optical element formed with a light energy curable resin having a shape, there are two regions with different releasability at the resin / mold interface, the inner region is the region with poor releasability, and the outer region is the region with good releasability. It is characterized in that it has a portion having a convex shape when viewed in a direction perpendicular to the base material surface in the outer peripheral portion of the region having poor releasability.

Further, according to the present invention, a light energy curable resin having a desired shape is formed on a base material by transferring a shape of a light energy curable resin using a mold, curing by light irradiation, and releasing. The method of manufacturing an optical element is characterized in that different materials are used for the contact surface with the resin of the mold.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings.

In the present invention, in order to reduce the releasing force itself, particularly the releasing force at the time of starting the releasing, a convex portion 23a is formed on the outer peripheral portion of the resin 23 molded as shown in FIG. It is provided so that stress is concentrated on the tip 23b and the mold is released from this portion with low stress. Here, 24 is a glass substrate. However, in order to form the outer peripheral portion into a shape such as 23a in FIG. 13, the mold structure becomes complicated, and it is necessary to control the amount of resin supplied and the process of filling the mold.

Therefore, according to the present invention, the shape of the outer peripheral portion of the resin molded as shown in FIG. 14 is not limited to a particular shape, and for example, a circular region having different releasability exists at the resin / mold interface. A region 25a having a good releasability on the outer side and a region 25b having a poor releasability on the inner side are provided with a convex shape 25c as viewed from the direction perpendicular to the substrate surface on the outer peripheral portion of the region 25b. Peeling starts in a region 25a with good stress under a low load, and stress is concentrated in this portion 25c at the start of mold release in a region 25b with a poor mold releasability, which enables mold release under a low load.

Further, in the present invention, the tip of the convex portion has a radius of curvature of 2 mm or less to enhance the stress concentration and enable the mold release under a lower load.

[Embodiment 1] FIG. 1 is a schematic view showing an embodiment of an optical element according to the present invention, FIG. 2 is a schematic view showing a mold used in this embodiment, and FIG. 3 is an optical element in this embodiment. FIG. 3 is a schematic view showing a manufacturing method of.

In FIG. 1, 1 is a light energy curable resin and 2 is a glass substrate. On the surface 1d of No. 1, fine irregularities transferred by the mold are formed. Reference numeral 1a denotes a resin good-releasing portion, 1b denotes a bad-releasing portion, and the outer periphery of the bad-releasing portion is convex like 1c. This molded product was produced using the mold shown in FIG.

FIG. 2 shows a mold having a groove 3d having a depth of 0.5 μm formed on quartz by photolithography and etching. The outside 3a of the groove forming portion is coated with a fluorine-based releasing agent of 1 μm or less. ing. 3b is a portion where the surface is still quartz, which is not coated with a fluorine-based releasing agent, and a tip has a convex portion with a radius of curvature of 2 mm like 3c at the boundary between 3a and 3b. Figure 3
A diffraction grating having fine irregularities on the surface was produced in the step shown in.

In FIG. 3, 4 is a light energy curable resin before curing, 5 is a spacer, and 6 is a releasing pin connected to a driving device (not shown). First, the light energy curable resin 4 is dropped onto the mold 3 (FIG. 3A), the glass base material 2 is placed thereon, and pressure is applied by an apparatus (not shown). A silane coupling agent is applied to the contact surface of the glass base material used with the resin for improving the adhesion. Then, when the resin thickness is determined by the spacer (FIG. 3B), light is irradiated to cure the resin (FIG. 3C). When the curing was completed, the glass part was released from the mold while gradually increasing the pressure with the release pin (FIG. 3 (d)). The end of 3a part starts to release at about 20 kN, and at 20 kN as it is, it releases to 3c part and 3
The part c begins to release from the edge of its tip at 25 kN,
The entire surface was released at 25 kN for about 10 seconds.

The light energy curable resin having a diffraction grating formed on the surface thus molded had no peeling between the resin and the glass substrate, and the edge portion of the grating was not chipped or deformed. Further, the mold was repeatedly used for 1000 shots. No change was observed in molding.

<Comparative Example 1> Molding was carried out in the same manner as in Example 1 except that a mold having no fluorine-based mold release agent was used. It took 150 kN to start the mold release, and the mold was released at once in less than 1 second. . In the molded product, the resin was partly peeled from the glass substrate.

Comparative Example 2 The same molding as in Example 1 was carried out except that the radius of curvature of the tip of the convex portion was 4 mm. It took 100 kN to start releasing the tip of the convex portion for 1 second. The following was released at once. In the molded product, the resin was partly peeled from the glass substrate.

[Embodiment 2] FIG. 4 is a schematic view showing an embodiment of an optical element according to the present invention, FIG. 5 is a schematic view showing a mold used in this embodiment, and FIG. 6 is an optical element in this embodiment. FIG. 3 is a schematic view showing a manufacturing method of.

In FIG. 4, 7 is a light energy curable resin, and 8 is a glass base material. The surface 7d of 7 has a Fresnel shape transferred by a mold. Reference numeral 7a denotes a resin good-releasing portion, 7b denotes a bad-releasing portion, and the outer periphery of the bad-releasing portion has a convex shape like 7c. This molded product was produced using the mold shown in FIG.

Reference numeral 9 in FIG. 5 is a mold having a Fresnel shape with a maximum depth of 25 μm on the surface, and KN is formed on the phosphor bronze base material 9a.
The plating 9b was applied to a thickness of 50 μm, and the plating layer was cut to form a Fresnel shape 9c. Figure 6
An optical element having a Fresnel-shaped resin layer adhered on the surface of a glass substrate was produced in the step shown in FIG.

In FIG. 6, 10 is a light energy curable resin before curing, 11 is a spacer, 12 is a mask, 13
Is a release pin connected to a drive device (not shown).
First, the light energy curable resin 10 is dropped on the mold 9 (FIG. 6A), the glass base material 8 is placed thereon, and pressure is applied by an apparatus (not shown). A silane coupling agent is applied to the contact surface of the glass base material used with the resin for improving the adhesion. Then, when the resin thickness is determined by the spacer (FIG. 6B), light is irradiated to cure the resin (FIG. 6B).
(C)). Here, after the resin was cured to a gel state, light irradiation was performed through the mask 12. The mask 12 has a shape as shown in FIG. 7 when viewed from above, and the tip portion has a convex portion 12a with a radius of curvature of 2 mm, and 12b does not transmit light. Therefore, the resin 7a portion is in a gel state. It remains the same (FIG. 6 (d)).

When the curing of the resin 7b portion was completed, the glass portion was released from the mold while gradually increasing the pressure by the release pin (FIG. 6 (e)). The end of 7a begins to release at about 10 kN,
The mold is released as it is up to 7c at 10kN, and the part 7c begins to be released at 25kN from the edge part at the tip, and it is left at 25k.
The entire surface was released with N in about 10 seconds. After releasing the mold, this time only the uncured portion 7a was irradiated with light to cure the portion 7a.

The light energy curable resin having the Fresnel shape formed on the surface thus molded did not separate the resin from the glass base material, did not have chipping or deformation of the edge portion of the lattice, and the mold was repeated 1000 shots. No change was observed in molding.

Comparative Example 3 The same molding as in Example 2 was carried out except that the entire surface was cured without masking during curing, but 200 kN was required to start the mold release, and the mold was released at once in less than 1 second. did. The edge of the Fresnel part of the molded product was chipped, and resin adhesion was found on the mold.

[Embodiment 3] FIG. 8 is a schematic view showing an embodiment of an optical element according to the present invention, FIG. 9 is a schematic view showing a mold used in this embodiment, and FIG. 10 is an optical element in this embodiment. FIG.

In FIG. 8, 14 is a light energy curable resin and 15 is a glass substrate. On the surface 14g of 14 is formed a Fresnel shape transferred by a mold.
Reference numeral 14a denotes a resin good-releasing portion, 14b denotes a bad-releasing portion, and the outer periphery of the bad-releasing portion is convex like 14c, 14d, 14e, and 14f. This molded product was produced using the mold shown in FIG.

Reference numeral 16 in FIG. 5 is a mold having a Fresnel shape 16i with a maximum depth of 40 μm on the surface, and a phosphor bronze base material 16a.
KN plating 16b was applied to 100 μm on the above, and the plating layer was cut to form Fresnel shape 16i. The outer side 16c of the Fresnel portion is coated with a fluorine-based release agent of 1 μm or less. 16d is a part where the fluorine-based release agent is not coated and the surface is KN, and 16e, 16f and 16 are formed at the boundary between 16c and 16d.
g and 16h, the tip has a convex portion with a radius of curvature of 2 mm. Using this mold, an optical element in which a Fresnel-shaped resin layer was adhered on the surface of the glass substrate was produced in the step shown in FIG.

In FIG. 10, 17 is a light energy curable resin before curing, 18 is a spacer, and 19 is a release pin connected to a driving device (not shown). First, the mold 16
The light energy curable resin 17 is dripping on the surface (see FIG. 10).
(A)), the glass base material 18 is placed thereon, and pressure is applied by an apparatus (not shown). A silane coupling agent is applied to the contact surface of the glass base material used with the resin for improving the adhesion. Then, when the resin thickness is determined by the spacer (Fig. 1
0 (b)), light is irradiated to cure the resin (FIG. 10).
(C)).

When the curing is completed, 14c, 14d, 14
The four glass parts outside the e and 14f parts were released from the mold while increasing the pressure (FIG. 10 (d)). The end of the portion 14a starts to be released at about 20 kN, and at 20 kN, 14c, 14d,
14c, 14f, 14c, 14d, 14
The e and 14f parts began to release from the edge part of the tip at about 25 kN. Immediately after the peeling was started at each of the convex portions, the load was once reduced to stop the peeling, and when the peeling was started at all four points, the load was applied again and the mold releasing was simultaneously started from the four points. Then, the four parts started to be released at 15 kN, and the entire surface was released at 15 kN in about 5 seconds.

The light energy curable resin having the Fresnel shape formed on the surface thus molded did not separate the resin from the glass substrate, and did not have chipping or deformation of the edge portion of the lattice.

Also, no change was found in the mold after repeated molding of 1000 shots.

<Comparative Example 3> The same molding as in Example 3 was carried out except that the convex portion was formed in one place, but it took 25 kN to start releasing the bad release portion, and the entire surface was released in about 10 seconds. . The molded product was partially chipped at the edge portion of the Fresnel portion 20b on the side opposite to 20a which was pressed at the time of release from the mold shown in FIG. This is because the mold release direction was a direction in which a force with which the edge is easily chipped was applied, and when the mold release direction was from the periphery to the center and the final mold release point was the center, as in Example 3. It seems that no chipping occurred.

As described above, there are two regions having different releasability at the resin / mold interface, the inner region is a region having a poor releasability, the outer region is a region having a good releasability, and the region having a poor releasability. By having a part of the outer peripheral part of the outer peripheral part of which the shape viewed from the direction perpendicular to the base material surface is convex, mold release under low load is possible and the mold release start point and mold release direction are controlled. it can.

[Embodiment 5] FIG. 12 is a schematic view showing the mold used in this embodiment. The mold used in Embodiment 1 has a coating portion of a fluorine-based releasing agent of 1 μm or less as 21a. The molding was performed in the same manner as in Example 1 except that the glass portion outside the 21a portion was pressed at the time of mold release.

The light energy curable resin having the diffraction grating formed on the surface thus molded did not separate the resin from the glass base material as in Example 1, and did not have chipping or deformation of the edge portion of the grating. Also, no change was observed in the mold after repeated molding of 1000 shots.

[0040]

As described above, according to the present invention, there are two regions having different releasability at the resin / mold interface, the inner region has poor releasability and the outer region has good releasability. By the region, the outer peripheral portion of the region having poor releasability, having a convex shape when viewed from the direction perpendicular to the substrate surface,
The release force at the start of release can be reduced, the start point of the release and the direction of the release can be controlled, peeling, deformation and destruction of the resin from the glass substrate can be prevented, and the durability of the mold can be improved.

Further, according to the present invention, it is possible to release the mold with a lower load, and it is possible to easily realize the difference in the mold release property by changing the surface material of the mold and to change the mold. It is possible to realize a difference in releasability.

[Brief description of drawings]

FIG. 1 is a schematic view showing an optical element in a first example.

FIG. 2 is a schematic view showing a mold used in the first embodiment.

FIG. 3 is a schematic diagram showing a method for manufacturing an optical element in the first embodiment.

FIG. 4 is a schematic diagram showing an optical element according to a second embodiment.

FIG. 5 is a schematic view showing a mold used in the second embodiment.

FIG. 6 is a schematic view showing a method for manufacturing an optical element in the second embodiment.

FIG. 7 is a schematic view showing a mask used in a second embodiment.

FIG. 8 is a schematic view showing an optical element in a third embodiment.

FIG. 9 is a schematic view showing a mold used in the third embodiment.

FIG. 10 is a schematic view showing a method for manufacturing an optical element in the third example.

11 is a schematic view showing a defective portion of the optical element molded in Comparative Example 3. FIG.

FIG. 12 is a schematic view showing a mold used in a fourth embodiment.

FIG. 13 is a diagram showing an optical element close to the present invention.

FIG. 14 shows an optical element according to the invention.

[Explanation of symbols]

1,7,14,20,23,25 Light energy curing type resin after molding and curing 2,8,15,21,24,26 Glass substrate 3,9,16,22 Mold 4,10,17 Before curing Light energy curing resin 5,11,18 Spacer 6,13,19 Release pin 12 Mask

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ identification code FI theme code (reference) G02B 5/18 G02B 5/18 G11B 7/24 538 G11B 7/24 538R 7/26 531 7/26 531 / / B29K 105: 24 B29K 105: 24 B29L 11:00 B29L 11:00 F Term (reference) 2H049 AA03 AA04 AA33 AA39 AA43 AA63 4F202 AH73 AJ03 AJ11 AR12 CA01 CB01 CD02 CD22 CD24 CD30 CK11 CM02 CM46 CM44 A4H75A73 EA03 EA04 EB01 EB11 EF01 EF05 EK17 EK18 5D029 KB08 MA34 5D121 AA06 DD02 EE26 EE28 GG02 GG30

Claims (5)

[Claims] 1. An optical element in which a light energy curable resin having a desired shape is formed on a base material by transferring a shape of a light energy curable resin using a mold, curing by light irradiation, and releasing. There are two regions with different releasability at the resin / mold interface, the inside is the region with poor releasability, the outside is the region with good releasability, and the base material surface of the outer periphery of the region with poor releasability And an optical element having a convex shape when viewed in a direction perpendicular to. 2. The optical element according to claim 1, wherein the convex tip has a radius of curvature of 2 mm or less. 3. Production of an optical element in which a light energy curable resin having a desired shape is formed on a base material by transferring a shape of a light energy curable resin using a mold, curing by light irradiation, and releasing. A method for manufacturing an optical element, characterized in that different materials are used for the contact surface with the resin of the mold. 4. The method of manufacturing an optical element according to claim 3, wherein the curing state of the light energy curable resin is different. 5. The method for manufacturing an optical element according to claim 4, wherein the masking is performed and light irradiation is performed.