JP3191447B2 - Method of manufacturing resin-bonded aspheric lens - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a "resin-bonded aspherical lens comprising a resin molded layer having an aspherical surface and a glass lens having a spherical or rough aspherical surface".

[0002]

2. Description of the Related Art Glass lenses are mainly used for lenses used in optical products such as cameras and microscopes. Glass lenses are manufactured by machining glass blocks (referred to as lens blanks) press-formed from glass in a molten state to produce lenses having a desired curvature. A method of manufacturing a resin lens by a method such as press molding, injection molding, or casting using resin instead of glass has also been put to practical use. With this method, once a mold is manufactured, a large number of lenses can be mass-produced using it,
The feature is that the manufacturing cost is low. However, the resin lens has a fatal disadvantage that the optical performance greatly changes due to a temperature change, and is not used for a high-precision lens.

Incidentally, there is an aspheric lens as a lens, and the surface shape is an aspheric surface. This is important because it has excellent performance that cannot be obtained with a spherical lens. At present, as a method of manufacturing an aspheric lens from glass, there are mainly a method of grinding a blank and a method of manufacturing by a direct press. However, the grinding process is low in mass productivity, and the direct press method has the disadvantage that the type and size of the glass type are limited and the equipment becomes expensive.

In order to solve this drawback, a resin-bonded aspheric lens as shown in FIGS. 2 and 3 has been developed. This is composed of a thin (for example, 5 to 100 μm) resin molding layer (2) having an aspheric surface and a glass lens (1) as a main component. The main glass lens (1) may be spherical (see FIG. 2: JP-A-60-56544) or rough aspherical surface (FIG. 3: JP-A-63).
-157103). Both are available at low manufacturing costs. Such a resin-bonded aspherical lens is manufactured by, for example, a manufacturing method including the following first to sixth steps. Please refer to FIG. First step: a step of horizontally placing a mold (3) having a desired aspherical surface; second step: a step of dropping a predetermined amount of a radiation-curable resin liquid (2a) at the center of the mold (3); 3rd step: a step of placing a glass lens (1) having a spherical or rough aspherical surface on a mold (3); 4th step: approaching a distance between the glass lens (1) and the mold (3) to a predetermined value. Fifth step: curing by irradiating the resin liquid (2a) sandwiched between the glass lens (1) and the mold (3) with radiation (4); and sixth step: curing Peeling the resin molded layer (2) obtained from the interface with the mold (3);

[0005]

In the conventional manufacturing method, bubbles (bubbles) sometimes enter the resin molding layer (2).
Bubbles enter the moment the resin liquid and the mold come into contact. Since the product containing foam becomes a defective product, the conventional production method has a problem that the yield rate is low. An object of the present invention is to improve the yield rate by preventing bubbles from entering.

[0006]

Accordingly, the present invention provides a first step: a step of placing a glass lens having a spherical surface or a rough aspheric surface horizontally; a second step: a predetermined amount of radiation curing at the center of the glass lens. A third step: a step of inverting the top and bottom of the glass lens; a fourth step: a step of placing the glass lens on a “mold having a desired aspherical surface”; a fifth step: the glass A step of causing the distance between the lens and the mold to approach a predetermined value; a sixth step: a step of irradiating the resin liquid sandwiched between the glass lens and the mold with radiation to cure the resin liquid; 7: a step of peeling off the resin molded layer obtained by curing from the interface with the mold; a resin-bonded lens comprising a resin molded layer having an aspherical surface and the glass lens. " And a method for producing the same.

[0007]

In the process of the present invention, the reason why bubbles are difficult to enter and the reason thereof will be guessed. Since the viscosity of the resin liquid is relatively low, when the resin liquid is dropped on a mold, it spreads horizontally by weight and the surface becomes almost flat. Therefore, when the glass lens is brought into contact with the flat resin liquid from above, the area where the resin liquid and the glass lens first come into contact is increased. In other words, surface contact. As a result, the air that was present between them escapes late and becomes bubbles. On the other hand, after dripping the resin liquid on the glass lens,
When the top and bottom are inverted, the resin liquid gathers at the center of the lens and takes the shape of an inverted pyramid. In this state, if the glass lens is brought into contact with the lower mold, the area where the resin liquid first comes into contact with the glass lens is reduced. In other words, it is point contact. As a result, the air that has been interposed does not delay the escape and does not contain bubbles. This is only an estimate. In any case, according to the experiment, it is apparent that bubbles are less likely to enter than the conventional method.

The main glass lens (1) may be a convex lens or a concave lens depending on the objective lens. This glass lens is preferably a spherical lens from the viewpoint of manufacturing cost. However, a lens having a rough aspherical joint surface may be used. The rough aspheric surface refers to a material having a processing accuracy that is coarser than desired processing accuracy or surface accuracy (for example, 6 μm or less or 3 μm or less), and having an aspheric surface that is the same as or approximate to the desired aspheric surface. Since such a glass lens may be coarser than desired processing accuracy, although it is an aspherical lens, its manufacturing cost does not increase significantly. A method for manufacturing such an aspherical lens is already known, and can be easily manufactured by a commercially available grinding machine. In order to improve the adhesive strength with the resin, it is preferable that the glass lens (1) is previously subjected to a silane coupling treatment.

[0009] The thickness of the resin molding layer (2) is generally 1 to
500 μm, preferably 5 to 100 μm. When the glass lens (1) has a highly accurate spherical surface, the resin molding layer (2) does not need to have the same refractive index as the glass lens (1). , It is preferable that the refractive indices are the same or similar. The resin molding layer (2) is a radiation-curable resin liquid (2a)
Is formed as a result of curing the resin liquid (2a) by irradiating the resin liquid. Such a resin liquid (2a)
The materials of the epoxy resin, unsaturated polyester,
Thermosetting resins such as polyurethane, ultraviolet curable resin, and modified acrylic resin are used. As the radiation, for example, ultraviolet rays, electron beams, γ rays, α rays, and the like are used.

Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited thereto.

[0011]

FIG. 1 shows the steps in the manufacturing method of this embodiment.
It is the conceptual diagram which looked at the glass lens (1), the metal mold | die (3), etc. from the side. FIG. 5 is a vertical sectional view of the concave lens manufactured in this embodiment. This lens is composed of a spherical glass lens (1) and an aspheric resin molding layer (2) formed on its surface. The thickness of the resin molded layer (2) is 5 to 100 μm at the center. On the other hand, glass lens (1)
Is a concave lens having an outer diameter of φ15 to φ40 mm and a center thickness of 3 to 10 mm. Both surfaces are polished to spherical surfaces.
The joint surface with the resin molding layer (2) has a spherical surface close to a desired aspherical surface. The surface of the glass lens (1) has been previously subjected to a silane coupling treatment in order to improve the adhesive strength with the resin molding layer (2). As a silane coupling agent, here, KBM503 (manufactured by Shin-Etsu Chemical Co., Ltd.) was used by diluting it in a 2 wt% ethanol solution. Next, the manufacturing method will be described for each step. First step: The glass lens (1) is placed horizontally. Second step: A predetermined amount of a radiation-curable resin liquid (2a) is dropped on the center of the glass lens (1). This is the state shown in FIG. As the resin liquid, an ultraviolet-curable resin called Aronix UV3700 or Aronix 3033HV (manufactured by Toa Gosei Chemical Co., Ltd.) was used. Third step: the glass lens (1) is turned upside down. At this time, if the resin liquid (2a) on the lens (1) is reversed quickly, the resin liquid (2a) on the lens (1) has an appropriate viscosity and does not drop off from the lens (1). FIG. 1 (b)
Is in this state. Fourth step: The glass lens (1) is lowered and placed on a mold (3) having a desired aspheric surface. The mold (3) has a surface plated with nickel. Fifth step: The glass lens (1) is pressed toward the mold (3). And a glass lens (1) and a mold (3)
To a predetermined value.

FIG. 1C shows this state. Sixth step: The resin liquid (2a) sandwiched between the glass lens (1) and the mold (3) is irradiated with radiation (ultraviolet rays) through the lens (1). Thereby, the resin liquid (2a)
Is cured to form a resin molded layer (2). Seventh step: The obtained resin molded layer (2) is peeled off from the interface with the mold (3).

Thus, the intended “aspherical concave lens comprising the aspherical resin molding layer (2) and the glass lens (1)” is manufactured. In the above process, the mold (3)
A method in which the resin liquid (2a) is dropped on the glass lens (1), and the mold (3) is turned upside down and placed on the glass lens (1) may be used.

[0014]

According to the present invention, even when a large number of lenses are manufactured, bubbles do not enter the resin molding layer (2), and the yield rate is improved.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing a vertical section of a lens (1) and the like in each step of a manufacturing method according to an embodiment of the present invention.

FIG. 2 is a schematic vertical sectional view of a conventional resin-bonded aspheric lens.

FIG. 3 is a schematic vertical sectional view of a conventional resin-bonded aspheric lens.

FIG. 4 is a conceptual diagram showing a vertical cross section of a lens (1) and the like in each step of a conventional manufacturing method.

FIG. 5 is a schematic vertical sectional view of a resin-bonded aspheric lens manufactured in an example of the present invention.

[Explanation of symbols]

 1 glass lens 2 resin molding layer 2a radiation (ultraviolet) curable resin liquid 3 mold 4 ultraviolet (a kind of radiation)

Claims (1)

(57) [Claims] 1. A first step: placing a glass lens having a spherical or rough aspheric surface horizontally; a second step: dropping a predetermined amount of a radiation-curable resin liquid on a central portion of the glass lens; a third step : A step of inverting the top and bottom of the glass lens; a fourth step: a step of placing the glass lens on a “mold having a desired aspherical surface”; a fifth step: a predetermined distance between the glass lens and the mold A step of causing the resin liquid sandwiched between the glass lens and the mold to be cured by irradiating radiation; and a seventh step: a resin obtained by curing. Removing the molding layer from the interface with the mold. A method for producing a "resin-joined lens comprising a resin molding layer having an aspheric surface and the glass lens".