JP2800898B2 - Manufacturing method of aspherical optical element - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing an aspherical optical element.

(Prior Art) When an optical element is made of a thermoplastic resin, there is a problem that the curing shrinkage is large and a desired shape accuracy cannot be obtained. In order to solve this problem, a molding method in which pressure is applied during the curing of the thermoplastic resin material has already been used, and shrinkage due to the curing of the thermoplastic resin material is inevitable. There has already been a method of manufacturing using a mold that allows for the amount of shrinkage.
In addition, even when an ultraviolet-curable resin material is used in place of the thermoplastic resin material, there is the same problem as described above.

 Countermeasures that solve this problem are already known.

For example, there is JP-A-62-258401. The technique disclosed in this publication is a method in which a resin is formed from a resin having a small curing shrinkage and pressure is applied in a direction in which the distance between the base lens and the mold is reduced when the resin is cured. Although the shape and precision of the resin formed by using this method are improved, it is necessary to apply a certain amount of pressure because there is no curing in low pressure molding.

(Problems to be Solved by the Invention) In order to solve the problems of the above-described conventional resin molding methods in which the curing shrinkage ratio is large and the shape accuracy is difficult to obtain, a mold is used in which the amount of curing shrinkage is estimated in advance. The method has a problem that a mold must be formed and measured every time the shape of a desired optical element is changed, and an expected amount must be calculated based on the measured value to create a regular mold. There is also a problem that this method requires much labor and time.

Also, in a method using a resin material having a small shrinkage,
There is a problem that the type of the resin material is small, difficult to obtain, and uncommon.

Further, in the method of applying pressure during curing of the resin material, it is not effective at a low pressure, so it is necessary to apply a certain amount of pressure. As a result, there is a possibility that the lens blank (base lens) may be damaged during operation. There is a problem that it can be applied only to an optical element made of a high-strength material or a thick optical element.

The present invention has been made to solve the above problems. That is, the mold is formed on the transfer surface that is exactly opposite to the molding surface shape of the desired optical element, and the molding material is also made of an extremely general urethane acrylate resin material. It is an object of the present invention to provide a method of manufacturing an aspherical optical element that is not required.

(Means for Solving the Problems) According to the present invention, a light-curable transparent resin material is disposed on a light-transmitting surface of an optical member, and a molding surface having a desired shape is formed on an upper surface of the light-curable transparent resin material. After the time when the photocurable transparent resin material is irradiated with light to be in a gel state has passed, while pressing and polymerizing the mold, the deformation due to curing shrinkage is suppressed, and the reversibility is reduced. And a method for manufacturing an aspherical optical element.

(Example) An example of the present invention will be described with reference to the drawings.

FIG. 1 is a plan view from the side showing an outline of an apparatus used in the present invention. FIG. 2 is an operation explanatory view showing a main part of the molding apparatus shown in FIG. 1 from a side. FIG. 3 is an explanatory view of the operation of the molding apparatus of FIG. FIG. 4 is an explanatory view of the operation of the molding apparatus of FIG. FIG. 5 is a plan view from the side showing a molded article molded according to the present invention.

The configuration of the apparatus used in the present invention will be described with reference to FIG. In the figure, reference numeral 1 denotes a central lower surface fitted with a base end portion of a cylindrical air cylinder 2 and guide bars 6 and 7 arranged in parallel on the left and right sides of the air cylinder 2 at desired intervals. A rectangular cylinder mounting plate member 1 mounted via support members 16 provided at the base ends of the cylindrical guide members 3 and 4, respectively.

The cylinder mounting member 1 has one end attached to a fixing member (not shown).

A cylinder shaft 5 is provided at a lower end surface at the center of the air cylinder 2, and a base end portion of an upper mold 9 is mounted via a mold plate 8 at an extending distal end surface thereof.

The template 8 on which the upper mold 9 is mounted is disposed in parallel with the cylinder mounting plate 1. The lower end of the cylinder shaft 5 is formed of a stainless steel alloy having a cylindrical surface on the lower end surface and a transfer surface opposite to the aspherical shape of the optical element 12 to be molded on the lower end surface. Parts are installed.

In the vicinity of the left and right sides of the upper surface of the template 8, the base ends of guide rods 6 and 7, which vertically slide in guide members 3 and 4 erected in parallel with the cylinder shaft 5, are respectively supported by support members. The air cylinder 2 is driven to move downward to press the material to be molded and to guide the material when molding.

At a lower position corresponding to the upper mold 9, a lower mold 10 having a cylindrical end surface having a desired spherical end surface corresponding to the spherical shape of the optical element to be molded is provided.
The lower mold 9 is configured to press-mold the material to be molded by descending.

In addition, the lower mold 10 is formed corresponding to the mounting surface of the glass blank 11 for mounting the end surface (transmission surface) of the glass blank 11 to be joined to the ultraviolet curing resin 12 to be molded on the front end surface thereof. I have.

On the outer periphery of the lower mold 10, a holding member 14 for holding and holding the outer periphery when the glass blank 11 is placed with a screw provided thereon is provided movably up and down. That is, the holding member
A screw which is screwed with a screw on the outer periphery of the lower mold 10 is provided on the inner diameter of the lower mold 10 and is rotated so that the outer peripheral wall of the lower mold 10 can move up and down. Further, a protruding press flange 15 is formed inside the distal end portion of the press member 14 so as to press the outer periphery of the glass blank 11 placed thereon.

The center of the lower mold 10 is provided with an ultraviolet irradiation lamp 18 disposed at a position below the lower mold 10 to irradiate the ultraviolet curing resin 12 on the glass blank 11 and allows the light flux to pass therethrough. An irradiation hole 13 is provided.

Next, a molding method of the present invention using the molding apparatus having the above-described configuration will be described.

First, the air cylinder 2 is driven, the upper mold 9 is raised, and a desired space is provided between the upper mold 9 and the lower mold 10, and the end face of the lower mold 10 is A glass blank 11 having a corresponding forming surface is placed, and an appropriate amount of an ultraviolet curable resin 12 is further placed on the glass blank 11. An ultraviolet irradiation lamp 18 disposed below the glass blank 11 is turned on the ultraviolet curing resin 12. That is, the luminous flux from the ultraviolet irradiation lamp 18 passes through the required hole 13 for the glass blank 11.
UV-curable resin
As shown in FIG. 2, when the hardening of the resin 12 into the gel state, the air cylinder 2 is driven to lower the upper mold 9, and the ultraviolet curing resin 12 is pressed at a predetermined speed and to a predetermined position. Molding.

During the above operation, that is, during the molding of the ultraviolet-curable resin 12 by pressing the upper mold 9, the ultraviolet-curable resin 12
UV irradiation is temporarily interrupted, and after the above-described predetermined pressurization and a predetermined time has elapsed, the UV-irradiation lamp 18 is again irradiated, and the curable resin 12 is again irradiated with the UV-ray to cure the UV-curable resin.
Irradiation is performed until the 12 is completely cured. After the curing, the air cylinder 2 is driven to move the upper mold 9 upward to release the upper mold 9 from the ultraviolet-curable resin 12.

The released UV-curable resin 12 is integrally joined to the surface of the glass blank 11 to form a predetermined resin layer. Further, the upper surface of the UV-curable resin layer 12 has an upper metal as shown in FIG. The predetermined aspherical surface is formed by accurately transferring the aspherical shape formed on the tip end surface of the mold 9.

In the above molding operation, generally, in the uniform molding of the wall thickness, when the ultraviolet curing resin 12 is pressed and molded without applying the pressure by the air cylinder 2 (only its own weight), the ultraviolet curing resin layer 12 is formed. Shrinks with curing and is molded. In this case, since the thickness is uniform, the entire region shrinks in the same manner, so that the shape of the transfer layer is transferred as it is and does not change. On the other hand, when the upper mold 9 having the aspherical surface formed at the tip end surface as in the above-described embodiment is pressed and formed by the air cylinder 2, the upper mold 9 is formed like the above-described spherical surface like the ultraviolet curable resin layer. Since the thickness is not uniform, the amount of shrinkage in a thick part is larger than that in a thin part. That is, the aspherical shape formed on the tip end surface of the upper mold 9 is not accurately transferred to the ultraviolet curable resin 12. To cope with such a phenomenon, the ultraviolet curable resin 12 is pressed and molded when it becomes a semi-cured state, that is, a gel state. More specifically, the curing shrinkage of the ultraviolet curable resin 12 is almost completely completed when the curing transition from the liquid state to the gel state occurs. Therefore, the upper mold 9 is operated and pressed in the gel state, that is, the soft state. Since the ultraviolet curable resin 12 has already contracted, the transfer by pressing the upper mold 9 does not shrink, so that accurate transfer can be performed.

(Second Embodiment) FIG. 6 is a plan view from a side showing main parts of a second embodiment of the present invention.

About the same structure and the same member as the said 1st Example, the same code | symbol is used and the description is abbreviate | omitted.

In the molding apparatus used in the first embodiment, first, the air cylinder 2 is driven to raise and stop the upper mold 9 at a predetermined position, and a desired interval is formed between the upper mold 9 and the lower mold 10. ,
A solution prepared by diluting a silane coupling agent KBM503 (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.) to about 1% by weight with ethanol on the spherical surface at the tip of the lower mold 10 is prepared by ordinary spherical polishing of optical glass. Glass blank (lens) 11
Is placed and uniformly applied to the upper surface of the aspherical surface of the glass blank 11 and dried at 80 ° C. for 20 minutes to form a bonding layer 19 for facilitating the bonding between the ultraviolet curable resin 12 and the glass blank 11. . Next, the mold release for facilitating the mold release after the molding of the ultraviolet curing resin 12 and the upper mold 9 on the tip end transfer surface of the aspherical upper mold 9 having the transfer surface opposite to the shape of the optical element to be molded. A solution obtained by diluting Agent KS-701 (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.) to about 10% by weight with toluene is uniformly applied, and heat-treated at 200 ° C. for 1 hour to form a release layer 20. Next, the upper mold 9 is driven to arrange the air cylinder 2 and the glass blank 11 having the spherical shape with a positional relationship as shown in FIG. At this interval, the desired thickness of the center of the optical element to be molded is set to about 1.6, and the gap is filled with an ultraviolet curing resin 12, and an ultraviolet irradiation lamp 18 is turned on to irradiate from the illumination hole 13 of the lower mold 10. When the ultraviolet curable resin 12 starts to cure and shrink due to the irradiation and becomes a gel state, the air in the air cylinder 2 holding the upper mold 9 is released to free the upper mold 9 and the air cylinder 2. State.

At this time, all of the weight is applied to the UV-curable resin layer 12 in the gel state. Where the UV curable resin
UV illuminance is 10m when average thickness of 12 is about 0.3mm
W / cm ² , and in this case, the gel state (measurement at room temperature is a penetration of 50 to 60) is 3 to 4 seconds after the start of the irradiation of the ultraviolet rays. That is, the weight of the upper mold 9 can be applied to the UV-curable resin 12 in a gel state by releasing the air cylinder 2 to release the upper mold 9 three to four seconds after the irradiation with the ultraviolet rays. The pressure required at that time is sufficient with an appropriate load that does not give optical distortion to the glass blank 11. That is, the weight of the upper mold 9 and the air cylinder 2 is sufficient, and no special weight is required.

After the UV-curable resin 12 has been cured, the optical element (the bonded body of the UV-curable resin and the glass blank) 12 and the upper mold 9 are in close contact with each other. The upper mold 9 rises and the state of close contact with the optical element 12 is easily released, and the molded optical element 12 is taken out to complete the process.

In the above embodiment, the determination that the UV-curable resin 12 is in the gel state is made based on the elapsed time from the start of the UV irradiation. This time varies depending on the material and amount of the ultraviolet curable resin 12 and the illuminance of the ultraviolet light to be irradiated, but under a certain condition, it is within a certain range. Therefore, create a sample that reproduces the state of formation,
By measuring the time when this sample is in a gel state and using the value in actual production, the determination of the gel state can be grasped by time. The gel state is JIS
The measurement can be performed based on the hardness of the gel by the penetration measurement as specified in the above.

In each of the above embodiments, when the ultraviolet curable resin 12 is irradiated with the ultraviolet irradiation lamp 18 to be in a gel state by irradiating the ultraviolet curable resin 12, the irradiation is stopped, and pressure molding is performed with the upper mold 9 while maintaining the gel state.
Although the molding surface was completely cured by irradiating ultraviolet rays again after the transfer, it is not necessarily limited to the above embodiment. When the ultraviolet curable resin 12 is gelled by irradiating ultraviolet rays, the air cylinder 2 is hardened. Is driven to lower the upper mold 9 to start molding, and during the gel state, the upper mold 9 is lowered to a predetermined thickness (interval) to be completely cured. That is, the ultraviolet curing resin 12 may be irradiated with ultraviolet rays to be in a gel state, and may be continuously molded under pressure until the curing is completed and the molding is completed.

Further, in each of the above embodiments, the glass blank 11 used was one in which the molding surface (aspheric molding surface) of the ultraviolet-curable resin 12 was formed in a concave molding surface. However, it is needless to say that a convex forming surface may be used. is there.

In each of the above embodiments, the upper mold 9 is released to a predetermined size by the air cylinder 2 which holds (supports) the upper mold 9. However, the air cylinder 2 does not completely release the air but a regulator is provided in the middle. Thus, the weight applied to the ultraviolet-curable resin 12 may be controlled.

Further, in addition to the urethane, acrylate, and epoxy resins used in the above embodiments, epoxy acrylate resins and the like may be used.

(Effect) In the method for producing an aspherical optical element of the present invention according to the above method, a pressure of several kg is sufficient because the pressure is applied in a gel state, and the curing shrinkage of the ultraviolet curable resin layer is reduced. As a result, it is possible to easily obtain a highly accurate reversibility of the shape, and it can be used for an optical element made of a material that is easily broken or an optical element having a small thickness, thereby enabling a design with a high degree of freedom.

Further, since no special resin is required, there is an effect that it can be manufactured at low cost.

[Brief description of the drawings]

FIG. 1 is a plan view from the side showing an outline of an apparatus according to an embodiment of the present invention. FIG. 2 is an operational plan view of a side portion of a main part of the molding of the apparatus shown in FIG. FIG. 3 is a side plan view showing the operation of the apparatus of FIG. 2; FIG. 4 is a plan view from the side showing the operation of the apparatus of FIGS. 2 and 3; FIG. 5 is a plan view from the side showing a molded article molded according to the present invention. FIG. 6 shows another embodiment of the present invention, and is an operation plan view from a side surface of a main part of the molding of the apparatus shown in FIG. 1 ... Mounting member, 2 ... Air cylinder 3,4 ... Guide member, 5 ... Cylinder shaft 6,7 ... Guide rod, 8 ... Model plate 9 ... Upper mold, 10 ... Lower mold 11: Glass blank, 12: UV-curable resin 14: Holding member, 18: UV irradiation lamp

Claims (1)

(57) [Claims] 1. A light-curable transparent resin material is disposed on a light-transmitting surface of an optical member, and a molding die having a molding surface in a desired shape is disposed on an upper surface of the light-curable transparent resin material. After the time when the photocurable transparent resin material is irradiated with light to be in a gel state has elapsed, while pressing and polymerizing the mold, the deformability due to curing shrinkage is suppressed to obtain reversibility. A method for manufacturing an aspherical optical element.