JP4887934B2 - Optical element molding apparatus and molding method - Google Patents

Description

  The present invention relates to a molding apparatus and molding method for an optical element made of an ultraviolet curable resin.

  Optical elements such as lenses used in optical devices such as cameras include glass and plastic. Compared to glass, plastic optical elements are widely used in many optical devices because they are lightweight, have excellent impact resistance, and can be manufactured at low cost.

  Plastic optical elements include those formed using a thermoplastic resin, those formed using a thermosetting resin, and those formed using an ultraviolet curable resin.

  The optical element made of a thermoplastic resin is formed by injection molding a thermoplastic resin such as polymethyl methacrylate (PMMA) or polycarbonate (PC). Although this method enables mass production in a short time, there are problems with internal homogeneity and lens surface transferability.

  The optical element made of thermosetting resin is formed by heat polymerization of a thermosetting resin such as diethylene glycol bisallyl carbonate (CR-39) by a casting method. This casting method has good internal homogeneity and lens surface transferability, but has a problem that mass production is poor because polymerization takes several hours to several tens of hours.

  In order to solve the above-mentioned problems of the casting method by heat polymerization, ultraviolet rays are irradiated to the ultraviolet curable resin using a high pressure mercury lamp, a metal halide lamp or the like as a light source, and the ultraviolet curable resin is polymerized and cured, so that a lens or the like can be quickly obtained. Various methods for mass-producing optical elements have been proposed.

As a matter of course, an optical element molding method using an ultraviolet curable resin must use a molding die such as glass that transmits ultraviolet rays. (For example, refer to Patent Document 1, Patent Document 2, and Patent Document 3).

JP-A-55-132221 Japanese Unexamined Patent Publication No. 07-1000083 Japanese Patent Application Laid-Open No. 08-1807

By the way, the molding device and the molding method for an optical element made of an ultraviolet curable resin have the following problems because a transparent glass mold must be used to transmit ultraviolet rays and the like.
(1) When the lens 101 as shown in FIG. 22 is molded, due to restrictions on the shape of the lens 101, as shown in FIG. 23, the opposing surfaces (cavity forming surfaces) of the pair of molds 102 and 103 are formed. The outermost peripheral portion 104 must be formed in an edge shape. However, when the molds 102 and 103 are made of glass, since the glass is brittle and easily broken, cracks 105 and the like are likely to occur in the outermost peripheral portion 104 as shown in FIG.
(2) When the molds 102 and 103 containing the crack 105 are used, when the uncured resin is filled in the mold, the uncured resin enters the minute crack 105 and the resin is cured and contracted. A part of the mold is peeled off from the crack 105. This phenomenon becomes more prominent as the amount of resin filled in the mold increases. This is because the larger the amount of resin filled in the mold, the greater the amount of absolute shrinkage and the greater the amount of penetration into the crack 105.

  An object of the present invention is to provide a molding apparatus and molding of an optical element such as a lens, which does not adversely affect the product even if cracks or the like which are the biggest problems of a mold such as glass occur. It is to provide a method.

The optical element molding apparatus of the present invention is a resin-made optical element by filling an energy curable resin into a cavity formed by clamping a pair of molds, at least one of which is made of glass, and curing it. In an optical element molding apparatus for molding
The surface of the cavity forming surface of the glass mold is covered with a protective film layer made of synthetic resin, and the protective film layer is integrally bonded to the optical element.

The optical element molding method of the present invention is a resin-made optical element in which an energy curable resin is filled and cured in a cavity formed by clamping a pair of molds, at least one of which is made of glass. In the method of molding an optical element, a protective film layer forming step of forming a protective film layer with an energy curable resin on the surface of a cavity forming surface of a glass mold, and the protective film layer by the protective film layer forming step A mold-clamping process for clamping a glass mold and a mold that is paired with the mold, and energy-curable resin is placed in the cavity between the opposing surfaces of the pair of molds clamped by the mold-clamping process. An energy curable resin filling step for filling, and the glass mold is passed through the energy curable resin filled in the cavity by the energy curable resin filling step. A curing step of irradiating curing energy light to cure the energy curable resin filled in the cavity and a pair of molds that are clamped are separated and cured in the cavity. An optical element extraction step of extracting the optical element from the pair of molds. Then, the protective film layer is integrally bonded to the optical element.

  In the optical element molding apparatus according to the present invention, a synthetic resin protective film layer is provided on the surface of the cavity forming surface of the glass mold, so that the cavity of the glass mold is formed. Even when cracks or the like are present on the surface, since the cracks or the like are covered with the protective film layer, even when an uncured ultraviolet curable resin is filled in the cavity and pressed to mold the optical element, The protective film layer prevents uncured ultraviolet curable resin from entering the cracks and the like.

  In the optical element molding method of the present invention, the protective film layer is formed on the surface of the cavity forming surface of the glass mold by the protective film layer forming step, and then the energy curable resin is filled in the cavity. The protective film layer prevents the filled uncured energy curable resin from entering the cracks of the glass mold. In the protective film layer forming step, the uncured ultraviolet curable resin for forming the protective film layer is formed by, for example, being applied to the surface of the cavity forming surface of a glass molding die, as in the case of molding an optical element. Therefore, it is possible to prevent the uncured ultraviolet curable resin forming the protective film layer from entering the cracks of the glass mold.

  The optical element molding apparatus and molding method of the present invention will be described below. FIG. 1 is a sectional view of an optical element molding apparatus (hereinafter simply referred to as a molding apparatus) 1.

  As shown in FIG. 1, the molding apparatus 1 includes a pair of upper and lower first and second molding dies 2 and 3 and a sleeve 4 for centering the first and second molding dies 2 and 3. I have. The first and second molds 2 and 3 are made of glass that transmits ultraviolet light as curing energy light. The glass is preferably made of a material having a high ultraviolet transmittance, such as synthetic quartz, but may be glass made of other materials. The first and second molds 2 and 3 can be moved up and down by a mold driving mechanism (not shown) and are inserted into and removed from the sleeve 4.

  Spherical or aspherical concave portions (concave surfaces) 5 are formed in the central portions of the upper and lower surfaces (opposing surfaces) as the cavity forming surfaces of the first and second molds 2 and 3. The flat part (flat surface) 6 is formed in the outer periphery of the. The concave portions 5 of the first and second molds 2 and 3 form an optical effective diameter portion of the optical element, and the flat portion 6 forms an attachment reference surface to a lens barrel or the like. A protective film layer 7 made of synthetic resin is provided on the upper and lower surfaces of the first and second molds 2 and 3, that is, the surface of the cavity forming surface. The protective film layer 7 made of synthetic resin is formed of an ultraviolet curable resin as a transparent energy curable resin.

  Then, as shown in FIG. 2, the first and second molding dies 2 and 3 provided with the protective film layer 7 of the ultraviolet curable resin are clamped in a state where a predetermined gap δ is provided. A cavity 8 is formed between the second molds 2 and 3 and, as shown in FIG. 3, uncured in the cavities 8 of the first and second molds 2 and 3, that is, inside the protective film layer 7. As the energy curable resin, an ultraviolet curable resin 9 is injected and filled from a resin injection gate 10 provided on the sleeve 4, and as shown in FIG. After irradiating the uncured UV curable resin 9 through the molds 2 and 3 to cure the UV curable resin 9, the first and second molds 2 and 3 are separated as shown in FIG. And removing it from the second mold 3, as shown in FIG. Wherein the Mamorumakuso 7 UV curable resin 9 is formed an optical element 11 which is integrally coupled.

  FIG. 7 is a flowchart showing the first embodiment of the optical element molding method of the present invention. In the method for molding an optical element according to the first embodiment, as a step 1, a protective film layer made of a synthetic resin that transmits ultraviolet light as curing energy light is formed on the surface of a cavity forming surface of a glass mold. Forming a film layer forming step and, as step 2, forming a pair of a glass mold having the protective film layer formed by the protective film layer forming step and a mold forming a pair with the glass mold. A mold clamping process for forming a cavity between opposing surfaces of the mold, and as step 3, curing is performed by filling the cavity of the pair of molds clamped by the mold clamping process with an ultraviolet curable resin as an energy curable resin. As a resin filling step and step 4, ultraviolet rays are passed through the glass mold to the ultraviolet curable resin filled in the cavity by the cured resin filling step. A step of irradiating and curing the ultraviolet curable resin filled in the cavity, and as a step 5, the pair of molds clamped are separated from each other and cured by ultraviolet curing in the cavity. And a product removal step for removing the optical element from the pair of molds.

  8 and 9 are explanatory views showing the protective film layer forming step. As shown in FIG. 8, uncured ultraviolet curable resin 7A is injected into the recess (concave surface) 5 of the cavity forming surface of the first mold 2 made of glass. Then, a protective film layer forming mold 203 having a convex portion (convex surface) 201 and a flat portion (flat surface) 202 having substantially the same shape as the concave portion 5 on the cavity forming surface of the glass mold 2 is centered. As shown in FIG. 9, the uncured ultraviolet curable resin 7 </ b> A is sandwiched between the protective film layer forming mold 203 and the glass mold 2 as shown in FIG. The uncured ultraviolet curable resin 7A is stretched along the recess 5 of the first mold 2 to form a resin layer having a predetermined thickness so as to cover the surface of the cavity forming surface, Is applied and cured to form a protective film layer 7 as shown in FIG. Similarly, as shown in FIG. 11, the protective film layer 7 is also formed on the second mold 3.

  Since the protective film layer 7 is thin, the amount of resin injected into the mold for forming the protective film layer 7 is small, and the absolute shrinkage amount when cured is small. Therefore, even when a crack or the like is present in the glass mold 2, it is possible to prevent the crack from being caused.

  The protective film layer 7 can be easily peeled off from the first and second molds 2 and 3, and after forming an optical element in the protective film layer 7 as described later, the optical element Is removed from the first and second molding dies 2 and 3 as a part of the optical element.

  In the mold clamping process of step 2, as shown in FIG. 2, the opposing surfaces as the cavity forming surfaces of the first and second molds 2 and 3 on which the protective film layer 7 is formed have a predetermined gap δ. A cavity (molding space) 8 is formed between these opposing surfaces.

  In the ultraviolet curable resin filling step of step 3, as shown in FIG. 3, the ultraviolet curable resin 9 is placed in the cavity 8 of the pair of molds 2 and 3 that are clamped, that is, inside the protective film layer 7. And pressurize. The UV curable resin 9 is brought into close contact with the inner surface of the protective film layer 7 by pressurization and is integrated with the protective film layer 7. Even if there are cracks or the like on the cavity forming surfaces of the first and second molds 2 and 3 made of glass, the cracks and the like are covered with the protective film layer 7, so that the ultraviolet curable resin is used. Even when the pressure 9 is pressurized, the ultraviolet curable resin 9 does not enter the cracks or the like.

  In the curing step of Step 4, as shown in FIG. 4, an ultraviolet curable resin filled inside the protective film layer 7 through the first and second molds 2 and 3 and the protective film layer 7 made of glass. 9 is cured by irradiating ultraviolet rays (UV).

  In the optical element extraction step of Step 5, as shown in FIG. 5, the pair of molds 2 and 3 that are clamped are separated so that the protective film layer 7 and the ultraviolet curable resin 9 are integrated. The optical element 11 as a resin molded product is taken out.

  FIG. 12 is a flowchart showing a second embodiment of the optical element molding method of the present invention. In the method of molding an optical element according to the second embodiment, as step 1, a pair of molds 2 and 3 using glass molds as at least one of the pair of molds are clamped. Then, a mold clamping process for forming a cavity between the opposing surfaces of the pair of molds 2 and 3 and, as step 2, a protective film layer is formed on the cavity forming surface with a synthetic resin that transmits ultraviolet light as curing energy light. A protective film layer forming step, as a step 3, an ultraviolet curable resin filling step of filling the inside of the protective film layer with an ultraviolet curable resin as an energy curable resin, and as a step 4, in the cavity by the ultraviolet curable resin filling step. The ultraviolet curable resin filled in the cavity is irradiated with ultraviolet rays through the glass mold and the protective film layer. A curing step to be converted, and as step 5, an optical element extraction step of taking out the optical element molded by opening the pair of molds clamped and ultraviolet curing in the cavity from the pair of molds, It has.

  FIG. 13 is an explanatory diagram showing the mold clamping process of Step 1. At least one of the first and second molding dies 2 and 3 is made of glass that transmits ultraviolet light. The upper and lower surfaces of the first and second molding dies 2 and 3 are opposed to each other with a predetermined gap δ. A cavity 8 is formed between the two.

  14-17 is explanatory drawing which shows the protective film layer formation process of the said step 2. FIG. As shown in FIG. 14, the cavity 8 of the clamped first and second molds 2 and 3 has a volume of the cavity 8 from the resin injection gate 10 provided on the centering sleeve 4. About 1 uncured UV curable resin 7A is injected. Thereafter, the uncured ultraviolet curable resin 7A is uniformly applied to the surface of the cavity forming surface as shown in FIG. 15 by rotating the first and second molds 2 and 3, for example. Then, as shown in FIG. 16, the ultraviolet curable resin 7 </ b> A becomes a hard protective film layer 7 by irradiating the ultraviolet curable resin 7 </ b> A with ultraviolet rays (UV) and curing it. By controlling the thixotropy (viscoelasticity) and the like of the uncured ultraviolet curable resin 7A, the ultraviolet curable resin 7A can be evenly applied to the surface of the cavity forming surface. As shown in FIG. 17, the protective film layer 7 is formed by spraying uncured ultraviolet curable resin in the mist in the form of a mist, forming a resin layer on the inner surface of the cavity, and then irradiating it with ultraviolet rays to cure. May be formed. Alternatively, the protective film layer 7 may be formed by blow molding. Since the protective film layer 7 is thin, the amount of resin for forming the protective film layer 7 is small, and the absolute shrinkage amount when cured is also small. Therefore, even when a crack or the like is present in the glass mold 2, it is possible to prevent the crack from being caused. When the protective film layer 7 is formed by the method shown in FIGS. 13 to 17, an appropriate means for preventing the resin injection gate 10 from being blocked by the protective film layer 7 is taken.

  FIG. 18 is an explanatory view showing the ultraviolet curable resin filling step of Step 3. In the ultraviolet curable resin filling step, a resin in which an ultraviolet curable resin 9 is provided in the centering sleeve 4 in the cavities 8 of the pair of molds clamped in the mold clamping step, that is, inside the protective film layer 7. Injection, filling and pressurization are performed from the injection gate 10. The UV curable resin 9 is brought into close contact with the inner surface of the protective film layer 7 by pressurization and is integrated with the protective film layer 7. Even if there are cracks or the like on the cavity forming surfaces of the first and second molds 2 and 3 made of glass, the cracks are covered and protected by the protective film layer 7. However, the ultraviolet curable resin 9 does not enter the crack.

  FIG. 19 is an explanatory diagram showing the curing step of Step 4. In the curing step, the ultraviolet curable resin 9 filled inside the protective film layer 7 is cured by being irradiated with ultraviolet rays through the glass first and second molds 2 and 3 and the protective film layer 7.

  In the optical element extraction step of Step 5, as shown in FIG. 5, as the resin molded product in which the pair of molds 2 and 3 that are clamped are opened and the protective film layer 7 is integrated. The optical element 11 is taken out.

  In the above embodiment, the case where a biconvex lens is formed as an optical element has been shown. However, as shown in FIGS. 20 and 21, the present invention is also applied to the case where a biconcave lens or a meniscus lens is formed. The present invention is applied to an imaging element such as a still camera, a digital camera, an optical pickup device, a portable information terminal, and a video camera, and an optical element used for a projection device, various measuring devices, a signal device, and the like. Moreover, although the case where the ultraviolet curable resin was used as an energy curable resin was shown, the energy curable resin may be a resin that is cured by light having a curing energy other than ultraviolet rays. In each of the above embodiments, the case where the protective film layer 7 is integrated as a part of the optical element 11 is shown. However, the protective film layer 7 may be configured to remain on the glass mold side. .

1 is a schematic cross-sectional view of an optical element molding apparatus. Sectional drawing of the state which clamped the 1st shaping | molding die and the 2nd shaping | molding die. Sectional drawing of the state filled with ultraviolet curable resin. Sectional drawing of the state which irradiated the ultraviolet-ray. FIG. 3 is a schematic cross-sectional view showing a state where an optical element is taken out. Sectional drawing of an optical element. The flowchart figure which shows the shaping | molding method of the optical element of 1st Embodiment. FIG. 3 is a schematic cross-sectional view showing a forming process of a protective film layer. FIG. 3 is a schematic cross-sectional view showing a forming process of a protective film layer. Sectional drawing of the 1st shaping | molding die which provided the protective film layer. Sectional drawing of the 2nd shaping | molding die which provided the protective film layer. The flowchart figure which shows the shaping | molding method of the optical element of 2nd Embodiment. Sectional drawing of the state which clamped the 1st shaping | molding die and the 2nd shaping | molding die. Sectional drawing of the state which inject | poured the ultraviolet curable resin for protective film layer formation in the shaping | molding die. Sectional drawing of the state which apply | coated the injected resin uniformly to the inner surface of a cavity. Sectional drawing which shows the state which has irradiated the ultraviolet-ray. Sectional drawing of the modification in the case of forming a protective film layer. Sectional drawing of the state which inject | poured ultraviolet curable resin inside the protective film layer. Sectional drawing which shows the state which has irradiated the ultraviolet-ray. Sectional drawing of the modification of an optical element. Sectional drawing of the modification of an optical element. Sectional drawing of the lens shape | molded by resin. Sectional drawing which shows the shaping | molding apparatus of the conventional lens. Sectional drawing which shows the problem of the shaping | molding die of glass.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Molding apparatus, 2 ... 1st shaping | molding die, 3 ... 2nd shaping | molding die, 4 ... Sleeve, 5 ... Recessed part (concave surface), 6 ... Flat part (flat surface), 7 ... Protective film layer, 8 ... Cavity , 9 ... UV curable resin, 11 ... optical element.

Claims (7)

In an optical element molding apparatus for molding an optical element made of resin by filling and curing an energy curable resin in a cavity formed by clamping a pair of molding molds made of glass at least one of them,
An apparatus for molding an optical element , wherein a surface of a cavity forming surface of the glass mold is covered with a protective film layer made of synthetic resin, and the protective film layer is integrally bonded to the optical element. The protective film layer, forming apparatus of an optical element according to claim 1 that is formed of an ultraviolet curable resin. In a molding method of an optical element, in which a resin-made optical element is molded by filling and curing an energy curable resin in a cavity formed by clamping a pair of molds at least one made of glass,
A protective film layer forming step of forming a protective film layer with an energy curable resin on the surface of the cavity forming surface of the glass mold;
A glass mold in which the protective film layer is formed by the protective film layer forming process and a mold clamping process for clamping a mold that is paired with the glass mold;
An energy curable resin filling step of filling an energy curable resin into the cavities of the pair of molds clamped by the mold clamping step;
A curing step of curing the energy curable resin filled in the cavity by irradiating the energy curable resin filled in the cavity by the energy curable resin filling step through the glass mold and curing energy light.
An optical element take-out step of taking out the optical element formed by separating the pair of molds clamped and curing in the cavity from the pair of molds , and
An optical element molding method in which the protective film layer is integrally bonded to the optical element. In the protective film layer forming step, an uncured energy curable resin is put into a cavity forming surface of the glass mold, and the uncured energy curable resin is used as a protective film layer forming mold to form the glass mold. of pressing the cavity forming surface, method of molding an optical element according to claim 3 that form a protective film layer is cured after the formation of the substantially uniform thickness of the coating along the cavity forming surface. In a molding method of an optical element, in which a resin-made optical element is molded by filling and curing an energy curable resin in a cavity formed by clamping a pair of molds at least one made of glass,
A mold clamping step of clamping the glass mold and a mold paired therewith;
A protective film layer forming step of forming a protective film layer with an energy curable resin on the surface of the cavity forming surface of the glass mold clamped by the mold clamping step;
An energy curable resin filling step of filling an energy curable resin into a cavity of the glass mold having the protective film layer formed by the protective film layer forming step and a molding die paired therewith;
A curing step of curing the energy curable resin filled in the cavity by irradiating the energy curable resin filled in the cavity by the energy curable resin filling step through the glass mold and curing energy light.
An optical element take-out step of taking out the optical element formed by separating the pair of molds clamped and curing in the cavity from the pair of molds, and
An optical element molding method in which the protective film layer is integrally bonded to the optical element. In the protective film layer forming step, the uncured energy curable resin is injected by injecting uncured energy curable resin into the cavity with the pair of molds clamped, and rotating the pair of molds. the optical-device forming method according to claim 5 that form a protective film layer is cured by irradiation with curing energy light after forming a coating film by coating a substantially uniform wall thickness in the cavity forming surface. The protective layer forming step, an uncured energy curable resin while clamping the pair of molds in said cavity by spraying a mist, after forming a substantially uniform coating on the cavity forming surface the optical-device forming method according to claim 5 that form a protective film layer is cured by irradiation with curing energy light.

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