JP2007313678A - Method for producing combination type optical element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a combination type optical element by molding an energy curing resin on a substrate which does not need devices for controlling vacuuming and a mold core temperature and aftertreatment after molding. <P>SOLUTION: The method for producing the combination type optical element includes a step in which the energy curing resin 1 is applied on the substrate 2, and energy is given and a step in which the energy curing resin on the substrate is press-molded at room temperature by a mold. In this method, energy to be applied to the resin and a time from the application of the energy to the press molding of the resin are determined to adjust the viscosity of the resin in press molding so that the resin can keep its shape when handled and be press-molded at a pressure preventing the occurrence of an optical strain in the optical element at room temperature. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing a composite optical element by molding an energy curable resin on a substrate. In particular, the present invention relates to a method for manufacturing a high-precision composite optical element that does not require post-processing for removing protrusion of resin after molding and control of mold temperature.

  The method of manufacturing a composite optical element according to the present invention is used for manufacturing a microlens array, a diffractive lens, a Fresnel lens, a subwavelength grating, and the like.

  In general, optical element manufacturing methods include grinding or polishing of a glass material or molding using a mold, or injection molding or press molding of a thermoplastic resin material. The glass material has less performance fluctuations with respect to environmental changes such as temperature than the resin material. On the other hand, molding with resin is excellent in shape accuracy. According to such characteristics of the material and the manufacturing method, the material and the manufacturing method are properly used.

  In the case of an optical element having a fine structure on the surface, a method of manufacturing a composite optical element by molding an energy curable resin on a glass substrate is employed. The reason is as follows. It is difficult to manufacture a fine structure on the surface from a glass material in terms of shape accuracy. On the other hand, when the entire optical element is made of a resin material, performance fluctuations with respect to environmental changes such as temperature increase.

  FIG. 11 is a flowchart of a conventional method for producing a composite optical element by molding an energy curable resin on a glass substrate. 12 to 14 are diagrams for explaining the method in relation to the apparatus. A procedure of a conventional method for producing a composite optical element by molding an energy curable resin on a glass substrate will be described with reference to FIG.

  In step S1110, as shown in FIG. 12, the glass substrate 2 is disposed on the support member 14 and is gripped by the gripping member 13.

  In step S1120, the energy curable resin 1 is supplied onto the glass substrate 2 as shown in FIG. The viscosity of the energy curable resin 1 is 0.1 to 300 Pa · s.

  In step S1130, the energy curable resin 1 is molded by the mold core 5 as shown in FIG.

  In step S1140, energy is supplied to the energy curable resin 1 from the glass substrate side during molding to cure the energy curable resin 1.

  In step S1150, as shown in FIG. 14, the glass substrate 2 and the energy curable resin 1 molded thereon are taken out from the mold core 5.

  The above conventional method is described in, for example, Patent Document 1.

  However, the above conventional methods have the following problems.

  In the step of supplying the energy curable resin 1 onto the glass substrate 2 (S1120), air bubbles may enter the energy curable resin 1 while the energy curable resin 1 develops on the glass substrate 2. Further, in the step of molding the energy curable resin 1 with the mold core 5 (S1130), air may remain between the mold core 5 and the energy curable resin 1. As a countermeasure against bubbles and air, a method of evacuating the space between the glass substrate and the mold member has been proposed. The above method is described in, for example, JP-A-9-24522.

  In the step of supplying energy to the energy curable resin 1 from the side of the glass base material during the molding and curing the energy curable resin 1 (S1140), if the energy is ultraviolet light, the ultraviolet light can be irradiated during press molding. Therefore, the structure of the mold core 5 and the apparatus becomes complicated. In addition, when the mold core 5 is made of a material that transmits ultraviolet rays, there are restrictions on the processing method using the material.

  In the step of curing the energy curable resin 1 (S1140), the energy curable resin 1 shrinks while being cured. Here, in order to cure while maintaining the pressure, it is necessary to increase the amount of the energy curable resin 1. For this reason, the energy curable resin 1 protrudes from the mold core 5. Therefore, a post-processing step for processing the protrusion is required.

  Post-processing steps include cutting, polishing, and burr finishing to finish the outer shape after molding. In this operation, cutting and polishing residue may adhere to the product surface. Since the surface of the product cannot be touched by hand, it is necessary to perform a cleaning process so as not to damage the surface of the product by immersing it in the cleaning liquid, and the product may be deteriorated by the cleaning liquid. It is also conceivable that scratches may occur due to the polishing residue itself at the time of cutting hitting the optical surface.

  In the step (S1140) of supplying energy to the energy curable resin 1 from the glass substrate side during the molding and curing the energy curable resin 1 (S1140), the energy curable resin 1 and the mold are added. The temperature of the core 5 rises. Therefore, in order to improve the accuracy of the molded product, temperature control of the mold core 5 is required. A method of manufacturing a composite optical element that controls the temperature of a mold is described in Patent Document 2.

Japanese Patent Laid-Open No. 2003-71858 Japanese Patent No. 3359631

  In the conventional method of manufacturing a composite optical element by molding an energy curable resin on a glass substrate, vacuuming or temperature control of the mold core is necessary to obtain a highly accurate molded product, A device for this is required. Moreover, post-processing after shaping | molding is required.

  Therefore, it is a method for producing a composite optical element by molding an energy curable resin on a base material, which does not require an apparatus for vacuuming or temperature control of the mold core, and post-processing after molding is not necessary. There is a need for unnecessary methods.

  The method for producing a composite optical element according to the present invention comprises the steps of applying an energy curable resin on a substrate and applying energy, and then pressing the energy curable resin on the substrate at room temperature by a mold. Forming. In the method for producing a composite optical element according to the present invention, the viscosity of the energy curable resin during press molding can maintain the shape during handling and causes optical distortion in the composite optical element at room temperature. The energy to be applied to the energy-curable resin and the time from the application of the energy to the press molding are determined so that the value can be press-molded at a pressure that is not applied.

  Since the energy curable resin is molded in a state where energy is applied and cured to some extent, bubbles are hardly generated between the mold and the energy curable resin. For this reason, evacuation is unnecessary. Further, since the energy curable resin is molded in a state where it is cured to some extent, heat generation due to polymerization or a crosslinking reaction can be suppressed when the energy curable resin is cured in the mold. For this reason, it is not necessary to control the temperature of the mold core. However, it is necessary to control the room temperature. In addition, since a post-processing step after molding is not required, the outer shape can be processed with a tolerance of ± 0.01 mm or less.

  According to the present invention, the mold shape can be transferred as it is because it can be molded at room temperature. Therefore, it is not necessary to correct the mold for thermal expansion during molding.

  In addition, the shape can be maintained during handling, and the composite optical element can be press-molded at a pressure that does not cause optical distortion at room temperature.

According to one embodiment of the present invention, the energy and energy applied to the energy curable resin are applied so that the viscosity of the energy curable resin during press molding is in the range of 10 ^{3 to} 10 ⁵ Pascal · second. Determine the time until molding.

  According to another embodiment of the present invention, in the step of applying energy curable resin on the substrate and applying energy, the substrate is attached to the spin coater and the spin coater is rotated to uniformly apply the applied energy curable resin. While giving energy.

  Therefore, as a result of making the thickness of the energy curable resin constant before molding, in the molding process, it is possible to prevent unfilling of the resin due to the small amount of the resin and excessive protrusion of the resin due to the large amount of the resin. it can. Further, even after the rotation is stopped, the energy curable resin is cured to some extent, so that the resin at the end portion does not return to the rotating shaft side, and the thickness is kept uniform even at the end portion.

  According to another embodiment of the present invention, when the energy is applied while rotating the spin coater to make the energy curable resin coated on the substrate uniform, the energy is not applied for the first predetermined time, and thereafter A second predetermined time energy is provided.

  Therefore, the thickness of the energy curable resin becomes uniform in the first predetermined time, and the energy curable resin is cured to some extent in the second predetermined time.

  According to another embodiment of the present invention, in the step of applying energy curable resin on the substrate and applying energy, a mask is provided on the side wall of the substrate, and the mask is removed after the step is completed.

  Therefore, it is possible to easily remove the resin protruding from the side wall of the base material.

  According to another embodiment of the present invention, in the step of molding the energy curable resin on the base material by the mold, the structure of the mold is a compression structure in the cavity and the resin does not escape. .

  Therefore, post-finishing of the molded product after molding becomes unnecessary.

  According to another embodiment of the invention, the substrate is a glass substrate.

  Therefore, it is possible to utilize both the performance of glass against environmental changes such as temperature and the processability of resin.

  According to another embodiment of the present invention, the energy curable resin is a type of resin that undergoes a curing reaction once energy is applied.

  Therefore, it is not necessary to give energy to the energy curable resin in the mold. In addition, since it is not necessary to give energy to the energy curable resin in the mold, the structure of the mold and the press molding apparatus is simplified.

  According to another embodiment of the invention, the energy is ultraviolet light.

  Therefore, energy can be easily given by irradiating the energy curable resin with ultraviolet rays.

  According to another embodiment of the present invention, the mold and the press molding apparatus are not configured to irradiate the energy curable resin with ultraviolet rays.

  Therefore, the structure of the mold and the press molding apparatus is simplified.

  FIG. 1 is a flowchart of a method for manufacturing a composite optical element by molding an energy curable resin on a substrate according to an embodiment of the present invention. 2 and 3 are diagrams for explaining the method in relation to the mold apparatus. The substrate may be ceramic or metal, but is glass in the following embodiments. A procedure of a method for producing a composite optical element by molding an energy curable resin on a glass substrate according to an embodiment of the present invention will be described below.

  In step S0110, the substrate is attached to the spin coater.

  In step S0120, an energy curable resin is supplied onto the substrate, and the spin coater is rotated. The rotation speed of the spin coater is, for example, 2000 rpm. The time for rotating the spin coater is a time necessary for making the thickness of the energy curable resin uniform. Specifically, the spin coater is rotated for 60 seconds. Here, the thickness of the energy curable resin is about 25 micrometers.

  In step S0130, while continuing to rotate the spin coater, the ultraviolet ray irradiation device is used to irradiate the energy curable resin with ultraviolet rays to cure the resin to some extent. Here, the degree of curing is preferably such that it can be molded at a low pressure. On the other hand, from the viewpoint of handling, a degree of curing that can maintain the shape is necessary. During the UV irradiation, the spin coater rotation speed remains at 2000 rpm.

  FIG. 4 is a diagram showing the relationship between the resin viscosity (horizontal axis) and the filling rate (vertical axis) by press molding with respect to various values of the press molding pressure. The resin to be press-molded is at room temperature. The filling rate is the ratio of the lattice height of the molded resin to the lattice height of the mold. The lattice height of the molded resin was measured with an atomic force microscope. In FIG. 4, the alternate long and short dash line indicates press forming pressure of 5 mega Pascal, the solid line indicates 10 mega Pascal, and the dotted line indicates press pressure of 30 Mega Pascal.

With a press forming pressure of 30 mega Pascal, optical distortion does not occur in the molded optical element. Even at a press pressure of 30 megapascals, if the resin viscosity exceeds 10 ⁵ pascal · second, the filling rate decreases. In this case, in order to perform press molding, it is necessary to heat and soften the resin. Therefore, press molding cannot be performed at room temperature.

On the other hand, if the resin viscosity is 10 ⁵ Pascal · sec or less, a filling rate of 90% or more can be achieved by press molding at room temperature even at a press molding pressure of 10 MegaPascal. The resin viscosity is preferably equal to or higher than the viscosity capable of maintaining the shape of the resin from the viewpoint of ease of handling. Specifically, it is preferably 10 ³ Pascal · second or more. That is, the resin viscosity at the time of press molding is preferably 10 ³ Pascal · second or more and 10 ⁵ Pascal · second or less.

FIG. 5 is a diagram showing the relationship between the time after UV irradiation (horizontal axis) and the resin viscosity (vertical axis) with respect to UV irradiation conditions. 5, one-dot chain line when irradiated with 30 mW / cm ² 5 sec, a solid line when irradiated with 45 mW / cm ² 10 seconds, and the dotted line shows the case of irradiation with 45 mW / cm ² 20 sec.

In the case of irradiation at 45 mW / cm ² for 10 seconds and irradiation at 45 mW / cm ² for 20 seconds, it takes about 500 seconds after the ultraviolet irradiation until the resin viscosity reaches 10 ⁵ Pascal · second. Therefore, when press molding is performed within 500 seconds after the ultraviolet irradiation, the irradiation may be performed at 45 milliwatts for 10 seconds to 20 seconds. When the time from the UV irradiation to the press molding is 500 seconds or more, the irradiation intensity or the irradiation time may be reduced.

  As described above, the curing rate can be controlled by controlling the amount of energy applied in step S0130. Until molding, while maintaining a certain degree of softness of the energy curable resin, it is possible to suppress heat generation due to polymerization or cross-linking reaction during the curing of the energy curable resin in the mold, resulting from the mold temperature rise due to heat generation Shape change can be suppressed.

  Here, it should be noted that, once energy is applied, it is not necessary to give energy in the mold by using a resin of a type in which the curing reaction proceeds. As this type of resin, there is a polymerization type resin, for example, an epoxy base material containing a polymerization initiator such as a sulfonium salt polymerization initiator. Other epoxy resins and acrylic resins may be used as long as they are the above types of resins.

  The reason why it is better to apply energy during the rotation rather than after the rotation of the spin coater is as follows. FIGS. 7 and 8 show the shapes of the energy curable resin when the spin coater is rotating and after the rotation is stopped, when energy is not applied during the rotation of the spin coater. During the rotation of the spin coater, as shown in FIG. 7, the thickness of the energy curable resin 1 is uniform. However, after the rotation is stopped, as shown in FIG. 8, it is considered that the resin at the end portion returns to the rotating shaft side, and the thickness of the end portion is increased. Next, FIGS. 9 and 10 show the shape of the energy curable resin 1 after the rotation of the spin coater is stopped when energy is applied during the rotation of the spin coater. Even after the rotation of the spin coater is stopped, since the energy curable resin 1 is cured to some extent, as shown in FIG. 9, the amount of the resin at the end returns to the rotating shaft side is small, and the thickness at the end is also small. Is held almost uniformly. In FIG. 9, a masking tape 21 is further attached to the side wall of the substrate 2. By removing the masking tape 21 after the rotation of the spin coater is stopped, the resin protruding from the side wall of the substrate 2 can be easily removed as shown in FIG. In FIG. 10, the portion of the resin protruding from the substrate 2 can be easily removed with a cutter or the like.

  Here, the point to be noted is that the thickness of the energy curable resin is made constant before molding in the subsequent process. As a result of making the thickness of the energy curable resin constant before molding, in the molding process, it is possible to prevent unfilling due to a small amount of resin and excessive protrusion due to a large amount of resin.

  In step S0140 of FIG. 1, the base material coated with the energy curable resin is attached to the mold. In FIG. 2, the base material is 2, and the energy curable resin applied on the base material is 1. The mold includes a mold core 5, a mounting plate 3, an upper mold plate 4, a lower mold plate 7, and a mounting plate 10. The mold further includes a base material compression core 8 and a base material compression block 11. As described above, the mold structure is a compression structure in the cavity and does not allow the resin to escape. Therefore, post-finishing after molding becomes unnecessary.

  In the present embodiment, the mold and the press molding apparatus (not shown) are not configured to irradiate the energy curable resin with ultraviolet rays. Therefore, the structure of the mold and the press molding apparatus is simplified.

  In step S0150, as shown in FIG. 3, pressure is applied to the core compression block 11, and the energy curable resin 1 is molded between the base material compression core 8 and the mold core 5. The pressure range is 5 to 30 megapascals. Thus, since it can shape | mold with a comparatively low pressure, it can shape | mold with the same press mechanism as the case where the resin which is not hardened is filled in the metal mold | die.

  In step S0160, the base material 2 and the energy curable resin 1 molded thereon are taken out of the mold.

  In this embodiment, the spin coater is used to apply the resin, but other devices such as a dispenser may be used.

  FIG. 6 shows a microlens array manufactured by the method of the present invention. A single-sided convex microlens made of an energy curable resin is disposed on the substrate. The number of microlenses does not correspond to the actual number for the purpose of simplifying the figure. The dimensions of the substrate are approximately 60 mm in length and width, the diameter of the microlens is approximately 50 μm, and the sag amount of the microlens is approximately 10 μm.

4 is a flowchart of a method for manufacturing a composite optical element by molding an energy curable resin on a substrate according to an embodiment of the present invention. It is a figure which shows the metal mold | die used for the method of shape | molding energy curable resin on the glass base material, and manufacturing a composite type optical element by one Embodiment of this invention. It is a figure which shows the metal mold | die used for the method of shape | molding energy curable resin on the glass base material, and manufacturing a composite type optical element by one Embodiment of this invention. It is a figure which shows the relationship between the resin viscosity (horizontal axis) and the filling rate (vertical axis) by press molding with respect to various values of the press molding pressure. It is a figure which shows the relationship between the time (horizontal axis) after ultraviolet irradiation and resin viscosity (vertical axis) with respect to ultraviolet irradiation conditions. It is a figure which shows the micro lens array manufactured by the method of this invention. It is a figure which shows the shape during rotation of a spin coater of energy curable resin when energy is not given during rotation of a spin coater. It is a figure which shows the shape after the rotation of a spin coater stops, when energy is not given during rotation of a spin coater. It is a figure which shows the shape of energy curable resin after rotation of a spin coater stops when energy is given during rotation of a spin coater. It is a figure which shows the shape of energy curable resin which removed the mask after rotation of a spin coater stopped when energy was given during rotation of a spin coater. 2 is a flowchart of a method for manufacturing a composite optical element by molding an energy curable resin on a glass substrate according to the prior art. It is a figure for demonstrating in relation to an apparatus the method to shape | mold an energy curable resin on a glass base material by a prior art, and to manufacture a composite type optical element. It is a figure for demonstrating in relation to an apparatus the method to shape | mold an energy curable resin on a glass base material by a prior art, and to manufacture a composite type optical element. It is a figure for demonstrating in relation to an apparatus the method to shape | mold an energy curable resin on a glass base material by a prior art, and to manufacture a composite type optical element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Energy curable resin, 2 ... Base material, 5 ... Mold core

Claims (10)

A method for producing a composite optical element obtained by molding an energy curable resin on a substrate,
Applying energy curable resin on a substrate and applying energy;
Thereafter, the step of press-molding the energy curable resin on the base material at room temperature with a mold,
The viscosity of the energy curable resin at the time of press molding is a value that can maintain the shape at the time of handling and can be press molded at a pressure that does not cause optical distortion in the composite optical element at room temperature. Thus, the manufacturing method which determines the time from giving the energy given to energy hardening resin and energy to press molding. The time from application of energy and energy to energy curing resin to press molding is determined so that the viscosity of the energy curing resin during press molding is in the range of 10 ^{3 to} 10 ⁵ Pascal · second. 2. The production method according to 1.   The energy curable resin is applied onto the substrate, and in the step of applying energy, the substrate is attached to the spin coater, and the spin coater is rotated to apply energy while making the applied energy curable resin uniform. The manufacturing method as described.   The energy is applied while rotating the spin coater to make the energy curable resin coated on the substrate uniform, and the energy is applied without applying the first predetermined time energy, and thereafter with the second predetermined time energy. 3. The production method according to 3.   The manufacturing method according to claim 3, wherein in the step of applying energy curable resin on the base material and applying energy, a mask is provided on the side wall of the base material, and the mask is removed after the step.   6. The step of molding an energy curable resin on a substrate with a mold, wherein the structure of the mold is an in-cavity compression structure with no resin escape. The manufacturing method as described.   The manufacturing method according to claim 1, wherein the substrate is a glass substrate.   The manufacturing method according to any one of claims 1 to 6, wherein the energy curable resin is a type of resin that undergoes a curing reaction once energy is applied thereto.   The manufacturing method according to any one of claims 1 to 6, wherein the energy is ultraviolet rays. The manufacturing method according to claim 9, wherein the mold and the press molding apparatus are not configured to irradiate the energy curable resin with ultraviolet rays.

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