JPH06345463A - Optical element and production process thereof and unit for producing optical element - Google Patents

Abstract

PURPOSE:To provide optical elements which has high shape and face precision and being suited for the mass production because of the inexpensiveness, production process and production equipment thereof. CONSTITUTION:A material for an optical element is set in a mold comprising top force, trunk force and bottom force, conveyed to preliminary heating state 2a, deformation stage 3a, cooling stages 4a through 9a in turn to soften the material with heat and deformed and cooled where the optimal cooling process is selected from a plurality of the processes depending on the thermal characteristics intrinsic to the mold to cool the molded optical elements. Consequently, fluctuation in the optical elements are suppressed and the stabilized molding of optical elements of high precision becomes possible.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical element manufactured by hot press molding and excellent in mass productivity and optical surface accuracy, a method for manufacturing the same, and an optical element manufacturing apparatus.

[0002]

2. Description of the Related Art In recent years, many optical elements such as lenses and prisms are molded by placing the optical element material in a molding die and heating and pressing it instead of polishing the optical element material such as glass. Proposed. However, in this case, once the temperature is raised and the pressure-molded optical element is cooled, the optical element contracts, causing a deviation from the desired shape of the optical element. The size of this shape deviation can be adjusted to some extent by the set temperature of the molding machine, but when a large number of molding dies are used to improve productivity, variations in the materials that make up the molding dies and processing errors, etc. Due to the difference in heat conduction peculiar to the molding die, the size of the deviation varies, which in turn leads to the variation in the characteristics of the molded optical element.

A conventional optical element molding apparatus is disclosed in, for example, Japanese Patent Application Laid-Open No. 62-292629.
A conventional molding apparatus will be described below with reference to the drawings. 4A and 4B show the configuration of a conventional molding apparatus. As shown in FIG. 4A, a first preheating stage 53, a second preheating stage 54, a pressure stage 55, and a cooling stage 56 are laterally (left and right in the drawing) mounted on a pedestal 52 provided in the chamber 51. Direction) are arranged in a line. Above the first and second preheating stages 53 and 54 and the pressure stage 55, the first and second preheating stages 53 and 54 are arranged so as to face each of the above stages.
The second preheating blocks 57 and 58 and the pressure block 59 are arranged. An upper die 60, a lower die 61, a body die 62, and an optical element material 63 are provided between each stage and each block facing each other.
Are arranged, and are set higher than the height of the molding block 64 by a predetermined amount.

The pressurizing block 59 is mounted movably up and down by a required stroke through a press cylinder 65 (Z direction in the drawing). First and second preheating stage 5
A heater 66 is embedded in the 3, 54 pressurizing stage 55, the first and second preheating blocks 57, 58, and the pressurizing block 59 so that they can be heated to a desired temperature. The cooling stage 56 has an inlet 67 and an outlet 68 of cooling water connected to an external temperature controller (not shown) in order to efficiently cool the entire molding block. A thermocouple (not shown) is embedded in each stage and each block to constantly detect the temperature.

To control the atmosphere in the chamber 51, an inlet 69 and an outlet 70 for an inert gas are connected. In addition, each stage is installed on the same surface so that the molding block can be transferred, and the first preheating stage 53 and the outside of the chamber are connected by a cradle 72.

A molding block 6 is provided on the right side surface of the chamber 51.
Four entrances 73 are provided, and a shutter 74 that can be opened and closed is provided. On the other hand, an outlet 75 is provided on the left side surface,
A shutter 76 is arranged.

The forming block 64 is provided in the chamber 51 as a first
As a means for transferring onto the preheating stage 53, the cylinder 77 can push the push rod 78 in the -X direction in the figure by a predetermined amount.

On the other hand, as a transfer means between the stages shown in FIG.
As shown in (b), the holders 80, 81, 82, and 83 provided on the transfer rod 79 arranged in the chamber 51 are fixed at the same pitch P as the arrangement pitch between the stages, and are arranged in the X direction. The transfer rail 84 can be moved by a predetermined amount by the Y-direction transfer rail 85.

[0009]

However, in the conventional molding apparatus as described above, it is possible to perform molding under the same conditions without taking into consideration the difference in heat conduction peculiar to the molding die and the change in the internal atmosphere of the molding apparatus. Therefore, when molded using a large number of molds, the characteristics of the optical element may vary,
This led to sudden appearance defects.

The present invention solves the above problems, and solves the above problems by providing an optical element molding apparatus and an optical element obtained by using the apparatus.

[0011]

In order to solve the above problems, the present invention comprises an upper molding die, a lower molding die, and a molding barrel die,
The optical element material is housed in the space formed by the upper mold, the lower mold, and the molding cylinder, and the optical element material is heated and pressed to mold the optical element material. Heating, and pressurize and deform while measuring the time from the start of deformation of the optical element material to the completion of deformation, select the cooling course corresponding to the time from the start of deformation of the optical element material to the completion of deformation, and cool The optical element is molded into the surface shape of.

Further, a molding die having an upper molding die, a lower molding die, and a molding barrel die, and containing optical element material in a space formed by the upper molding die, the lower molding die, and the molding barrel die is preheated. A molding method in which an optical element material is heated and softened, deformed under pressure, and cooled by being conveyed in order of a stage, a deformation stage, and a cooling stage, and the molding is detected by the time from the start of deformation of the optical element material to the completion of deformation. Depending on the mold-specific thermal properties,
A plurality of cooling courses are selected and manufactured.

An upper molding die, a lower molding die and a molding barrel die are provided,
A molding die configured to store the optical element material in the space formed by the upper molding die, the lower molding die, and the molding barrel die is conveyed in the order of the preheating stage, the deformation stage, and the cooling stage to heat and soften the optical element material, A molding device that deforms under pressure and cools, and is provided with a plurality of cooling courses that are selected according to the thermal characteristics unique to the mold.

Further, the time from the start of the deformation of the optical element material to the completion of the deformation is detected, and the cooling course of the molding die is selected.

[0015]

According to the molding apparatus as described above, the temperature variation after the completion of the deformation of the optical element material, which is caused by the difference in heat conduction peculiar to the molding die, is absorbed, and the characteristic of the optical element is stabilized. . Further, in the optical element molding method, it is possible to select the cooling pattern corresponding to the deformation completion time in the cooling step by measuring the deformation completion time of the optical element material in the deformation step. Furthermore, the optical element obtained by using the above-described molding apparatus and molding method has the function of satisfying desired performance and appearance and having high stability.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An optical element molding apparatus according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows the configuration of the optical element molding apparatus of this embodiment, FIG. 2 shows the state in which a molding die is placed on the deformation stage, and FIG. 3 shows the configuration of the optical element obtained by the molding method of this embodiment. As shown in FIG. 1, a preheating stage 2a, a deformation stage 3a, cooling stages 4a to 9a, and a water cooling stage 10a are arranged in the chamber 1 in the lateral direction (the lateral direction in the drawing). The cooling process is 4a,
It is divided into a course A consisting of 5a, a course B consisting of 6a and 7a, and a course C consisting of 8a and 9a, and arranged in parallel with each other. Each stage has a built-in heater so that the temperature can be controlled. Further, of the cooling courses A to C, the first cooling stage 4
a, 6a, 8a as cooling 1 and the second cooling stage 5
Let a, 7a, and 9a be cooling 2. Further, as shown in FIG. 2, the heater block 3b is arranged so as to face the deformation stage 3a, but similarly, a heater block (not shown) is arranged so as to face each of the stages 2a to 10a, and a heater is provided for each. Is incorporated, and temperature control is possible. The height of the heater block facing the stages 2a to 10a is set to be larger than the height of the molding die when the optical element material is inserted by a predetermined amount. Further, the chamber 1 is provided with an inlet 21 and an outlet 22 for an inert gas or the like, and the atmosphere inside the chamber 1 is constantly controlled. The stages 2a to 10a are installed on the same plane so that the mold can be transported. Further, the preheating stage 2a and the outside of the chamber are connected by a preparatory stand 11 on the same plane as the preheating stage 2a. Further, the water cooling stage 10a and the outside of the chamber are connected by a pedestal 14 on the same plane as the water cooling stage 10a, so that the molding die can be loaded and unloaded smoothly. A molding die inlet 12 is provided on the left side surface of the chamber 1, and an openable / closable shutter 13 is provided. On the other hand, an outlet 15 is provided on the right side surface, and a shutter 16 that can be opened and closed is provided. The shutter 1 is used when the mold is loaded and unloaded.
3, 16 are configured to open and close. The means for conveying the molding die into the molding apparatus is performed by using a slidable molding die conveying arm 18 connected to an air cylinder 17 installed on the left side of the preparation table 11. Further, the conveyance of the molding die in the molding apparatus is performed by the transportation rod 19. Holders 20 to 24 for holding the mold and smoothly conveying the mold without vibration are fixed to the rod. The molding die is moved by moving the transport rail 25 in the (+) X direction by a predetermined amount P. The holders 20 to 24 are waiting above each stage until just before the mold is conveyed.
When carrying to the next stage, it descends and carries.
After that, the transport rail 25 once moves above the height of the mold and then moves by P in the (-) X direction to return to the original position. The die 19 is carried by the rod 19 from the deformation stage 3a to the first cooling stages 4a, 6a, 8a, but a guide 26 for allocating to one selected course out of the three courses is provided. The conveying of the molding die is not limited to the conveying means of the present embodiment as long as it can send the molding die to the cooling course selected by the program, and a plurality of cooling courses may be provided. Good.

Next, as shown in FIG. 2, the forming die 27 has a barrel die 30 which is adjusted to an arbitrary height so as to eliminate the axial deviation between the upper die 28 and the lower die 29 and to have a predetermined optical element thickness. And the spherical optical element material 31 is placed in the space surrounded by the upper mold 28, the lower mold 29, and the body mold 30. A plurality of molding dies 27 are prepared in consideration of mass productivity, and the total height, the outer diameter, and the like are managed with an accuracy of the order of μm. The heater block 3b of the deformation stage 3a is connected to the air cylinder 32 so that a desired pressure can be applied to the upper mold 28. An air cylinder 32 and a cylinder rod 33 connected to the heater block 3b.
A measuring device 34 for measuring the amount of deformation of the optical element material is installed via. Further, the deformation amount measuring device 34 is connected to the timer 35. The deformation completion time is measured by measuring the time when the deformation is completed by the deformation amount measuring device 34 with the timer 35.

The deformation completion time is the time from when the heater block 3b starts descending until the lower surface of the brim portion of the upper die 28 of the molding die 27 and the upper end portion of the body die 30 come into contact with each other. The measured deformation completion time is sent to the arithmetic unit 36 connected to the timer 35, and is conveyed to a desired cooling course according to a program previously input to the arithmetic unit 36.

A molding method using the above molding apparatus will be described below. First, the optical element material 31 is put into the molding die 27 and placed on the preparation table 11. After the shutter 13 at the inlet 12 of the molding apparatus is opened, the molding die 27 is conveyed to the preheating stage 2a in the molding apparatus by the molding die loading arm 18 connected to the cylinder 17. When the conveyance is completed, the entrance shutter 13 is closed and the mold is heated to the temperature at which the preheating stage 2a is set in advance. Next, the heated mold is conveyed to the press stage 3a, the heater block 3b descends, comes into contact with the upper mold 28 of the mold 27, and a desired pressure is applied to perform pressure molding. The deformation completion time at this time is measured by the deformation amount measuring device 34 and the timer 35, and is distributed to the cooling courses A to C. The set temperature of each cooling course set by the deformation completion time is shown in (Table 1). This set temperature is determined from past data and is the optimum condition for obtaining an optical element having a good appearance and characteristics.
This condition takes into consideration the difference in the heat conduction state peculiar to each mold, which is caused by the dispersion of the materials forming the mold, the processing error of the mold, or the oxidation state of the surface which changes depending on the usage condition. . The molding die which has completed the molding is conveyed to the selected cooling course, and is cooled to the set temperature through the primary cooling and the secondary cooling. Further, the mold passing through the above cooling course is conveyed to the water cooling stage 10a and cooled to a temperature at which the optical element can be taken out.
After cooling, the optical element is taken out from the molding die.

[0020]

[Table 1]

In this embodiment, a ball type glass material of SF8 is used as the optical element material, the temperature of the preheating step is set to 490 ° C., the setting temperature of the deformation step is 490 ° C., and the press pressure is 3 kgf / cm ² . The temperature was set and the cooling step was performed under the conditions shown in (Table 1). 5 by the above molding method
Molding was performed 5 times using each molding die. The shape of the optical element obtained by this method is shown in FIG. The characteristics (transmitted wavefront aberration) of the obtained optical element were measured using a Fizeau interferometer, and the results shown in Table 2 were obtained. Further, the characteristics of the optical element obtained by the molding method using the conventional molding device are shown in (Table 3). Comparing (Table 2) and (Table 3), the light obtained by the molding method of this example is shown.

[0022]

[Table 2]

[0023]

[Table 3]

The characteristic variation of the optical element is reduced by 0.010λ for the first type and 0.004λ for the second type, and 0.00 for the third type, compared to the characteristic variation of the optical element obtained by the conventional molding method.
A decrease of 9λ, a decrease of 0.006λ in type 4, and a decrease of 0.004λ in type 5 were obtained. Further, in the case of the optical element obtained by the molding method of the present example, the variation in characteristics due to each molding die is 0.002λ as shown in (Table 2), but the optical element obtained by the conventional molding method. In the case of, the result was 0.005λ as shown in (Table 3).
As described above, it can be seen that the characteristics of the optical element obtained by the molding method using the molding apparatus of this embodiment are very stable. In addition, there was no appearance defect, and the molded optical element maintained a uniform shape.

In this embodiment, the preheating step, the deformation step,
Each water cooling process has one stage, and each cooling process has 3 stages.
There was one course and two stages each, but the number of stages and cooling courses in each process are not limited to this. Further, the optimum configuration may be made in consideration of the difference in the material and shape of the optical element, the material of the molding die used, and the like.

[0026]

As is apparent from the description of the above embodiments, according to the present invention, the deformation completion time of the optical element material during the molding process is measured, and the cooling course is selected according to the difference in the deformation completion time. It is possible to provide a highly accurate and stable optical element, a method of manufacturing the same, and a manufacturing apparatus for which the appearance and characteristics of the optical element are made uniform.

[Brief description of drawings]

FIG. 1 is a lateral cross-sectional view of a main part of a molding apparatus according to an embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view showing the configuration when a molding die is placed on the deformation stage.

FIG. 3 is a vertical sectional view showing the structure of an optical element obtained by the molding method.

FIG. 4A is a vertical cross-sectional view showing the structure of a conventional molding apparatus, and FIG.

[Explanation of symbols]

 1 Chamber 2a Preheating Stage 3a Deformation Stage 4a-9a Cooling Stage 10a Water Cooling Stage 11 Preparation Stand 12 Entrance 13, 16 Shutter 14 Receiving Stand 15 Exit 26 Guide 27 Mold 28 Upper Mold 29 Lower Mold 30 Body 31 Optical Element Material 32 Air Cylinder 33 Cylinder rod 34 Deformation amount measuring device 35 Timer 36 Computing device 37 Optical element

Claims (4)

[Claims] 1. An upper forming die, a lower forming die, and a forming body die,
The optical element material is housed in the space formed by the upper molding die, the lower molding die and the molding barrel die, and the optical element material is heated,
An optical element molded by pressurization, wherein the optical element material is heated to its thermal deformation temperature and pressure-deformed while measuring the time from the deformation start to the deformation completion of the optical element material, An optical element formed by selecting a cooling course corresponding to the time from the start of deformation of a material to the completion of cooling and cooling the material to form a predetermined surface shape. 2. An upper forming die, a lower forming die, and a forming body die,
A molding die having a configuration in which an optical element material is housed in a space formed by the upper molding die, the lower molding die, and the molding cylinder die is conveyed in order of a preheating stage, a deformation stage, and a cooling stage to heat the optical element material. A molding method in which the optical element material is softened, deformed under pressure, and cooled, and a plurality of cooling courses are selected according to the thermal characteristics peculiar to the mold detected by the time from the deformation start to the deformation completion of the optical element material. Optical element manufacturing method. 3. An upper forming die, a lower forming die, and a forming body die,
A molding die having a configuration in which an optical element material is housed in a space formed by the upper molding die, the lower molding die, and the molding cylinder die is conveyed in order of a preheating stage, a deformation stage, and a cooling stage to heat the optical element material. An optical element manufacturing apparatus having a plurality of cooling courses, which is a molding apparatus that softens, deforms under pressure, and cools, and is selected according to the thermal characteristics unique to the molding die. 4. The optical element manufacturing apparatus according to claim 3, wherein the cooling course of the molding die is selected by detecting the time from the start of the deformation of the optical element material to the completion of the deformation.